JPH11323469A - Hydrogen storage alloy and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the problem that hydrogen is hard to be released because of too high stability between an Mg-rare earth hydrogen storage alloy and hydrogen and to obtain a hydrogen storage alloy capable of easily realizing a hydrogen storage occluding electrode having a large discharging capacity by incorporating it with an alloy ingot having a specified compsn. or the pulverized material thereof. SOLUTION: This invention contains an alloy ingot or the pulverized material thereof having a compsn. expressed by the formula of Mg1-a-b Rla Mlb Niz and is obtd. by a casting method or a sintering method in such a manner that a hydrogen storage alloy raw material is heated to melt, is cast and is thereafter subjected to heat treatment, where Rl denotes one or more elements selected from rare earth elements including Y, Ml denotes one or more elements selected from the elements having electronegativity higher than that of Mg (where the elements in Rl, Cr, Mn, Fe, Co, Cu, Zn and Ni are excluded), and 1<=a<=0.8, 0<=b<=0.9, 1-a-b>0 and 3<=z<=3.8 are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage alloy and a secondary battery provided with a negative electrode including the hydrogen storage alloy.

[0002]

2. Description of the Related Art A hydrogen storage alloy is an alloy that can safely and easily store hydrogen as an energy source, and is attracting much attention as a new energy conversion and storage material. The fields of application of hydrogen storage alloys as functional new materials include hydrogen storage and transport, heat storage and transport, thermo-mechanical energy conversion, hydrogen separation and purification, hydrogen isotope separation,
A wide range of proposals have been made for batteries using hydrogen as an active material, catalysts in synthetic chemistry, temperature sensors, and the like.

Further, in recent years, nickel-hydrogen secondary batteries using a hydrogen storage alloy as a negative electrode material have a high capacity,
It has the characteristics of being resistant to overcharge and overdischarge, capable of high-rate charge / discharge, being clean, and being compatible with nickel-cadmium batteries. Attention has been paid to its application and practical application at present. Thus, the hydrogen storage alloy,
Utilizing its physical and chemical properties, it has potential for various applications and can be counted as one of the key materials in the future industry.

[0004] Metals that occlude hydrogen include metal elements that react exothermically with hydrogen, ie, can form stable compounds with hydrogen (eg, Pd, Ti, Zr, V, and other rare earth metal elements, alkaline earth elements). ) May be used alone, or these metal elements may be alloyed with other metals.

[0005] One advantage of alloying is that the bonding force between metal and hydrogen is appropriately reduced so that not only the occlusion reaction but also desorption (release) occurs.
The reaction should be relatively easy. The second advantage is the size of the hydrogen gas pressure (equilibrium pressure; plateau pressure) required for the reaction, the width of the equilibrium region (plateau region), the change in the equilibrium pressure during the process of absorbing hydrogen (flatness). Storage and release characteristics such as A third advantage is that chemical and physical stability is enhanced.

Incidentally, the composition of a conventional hydrogen storage alloy is as follows: (1) Rare earth-based alloys (eg, LaNi ₅ , MmNi
₅ ), (2) Laves system (eg, ZrV ₂ , ZrMn ₂
(3) titanium-based (for example, TiNi, TiFe, etc.),
(4) Magnesium (eg, Mg ₂ Ni, MgNi
₂ ) and (5) Others (for example, cluster alloys).

Among these, the rare earth hydrogen storage alloy (1) has been put to practical use as an electrode material. However, the discharge capacity of an alkaline secondary battery provided with this electrode has reached 80% or more of the theoretical capacity, and there is a limit to further increasing the capacity.

By the way, the rare earth -Ni-based intermetallic compounds (1), there are many other than the ₅ type AB. Mat. R
es. Bull. , 11, (1976) 1241,
It is disclosed that an intermetallic compound containing a rare earth element in a larger amount than the AB ₅ type absorbs a larger amount of hydrogen at around room temperature than the AB ₅ type. In addition, it has been reported that a magnesium-rare earth alloy having a composition obtained by substituting magnesium for a rare earth-Ni alloy absorbs a large amount of hydrogen gas (for example, Taisho Ohkaku, Soda and Chlorine, 34, 447 (198)).
3)).

Among alloys having such a composition, for example, La
_{The 1-X} Mg _X Ni ₂ alloy has a problem that the hydrogen release rate is very low because of its high stability with hydrogen. Less-Common Met, 73, 3
39 (1980). Oesterreich
er et al. In addition, K. Kadir
Et al., Abstracts of the 120th Spring Meeting of the Japan Institute of Metals,
289 (1997) reports a hydrogen storage alloy of PuNi ₃ type having a composition of Mg ₂ LaNi ₉ .

However, although the magnesium-rare earth alloy having the composition described above has a large hydrogen storage capacity in the gas phase, the electrode containing this alloy hardly functions in an alkaline electrolyte at room temperature. Having.

Japanese Patent Application Laid-Open Nos. 62-271348 and 62-271349 disclose Mm _1-x A
hydrogen absorbing electrode comprising a hydrogen storage alloy represented by _x Ni _a Co _b M _c, the hydrogen absorbing electrode comprising a hydrogen storage alloy represented by _{La 1-x A x Ni a} Co b M c are disclosed respectively .

[0012] However, the metal oxide / hydrogen secondary batteries provided with these hydrogen storage electrodes have a problem that the discharge capacity is low and the cycle life is short.

[0013] In addition, republished patent publication WO97 / 0321.
No. 3 has a composition represented by the general formula (i): (R ₁ -XL _x ) (Ni
Disclosed is a hydrogen storage electrode represented by _{1-YM Y} ) _Z , having a specific antiphase boundary, and including a hydrogen storage alloy whose crystal structure is represented by a LaNi ₅ type single phase. This hydrogen-absorbing alloy is prepared by melting a molten alloy having the composition represented by the general formula (i) with irregularities on the surface and having an average maximum height of 3 irregularities.
On a roll of 0 to 150 μm, the degree of supercooling is 50 to 500 ° C.,
Under cooling conditions of a cooling rate of 1,000 to 10,000 ° C./sec,
It is manufactured by uniformly solidifying to a thickness of 0.1 to 2.0 mm and then performing a heat treatment. Further, it is described that, if the manufacturing conditions are not satisfied, the obtained alloy is composed of two phases of LaNi ₅ type crystal grains and Ce ₂ Ni ₇ type crystal grains, and a LaNi ₅ type single phase structure cannot be obtained. Have been.

However, a metal oxide having a negative electrode containing a hydrogen storage alloy whose composition is represented by the aforementioned general formula (i), which has a specific antiphase boundary, and whose crystal structure is a LaNi ₅ type single phase. Product / hydrogen secondary battery has a problem that both the discharge capacity and the cycle life are not satisfactory.

[0015]

SUMMARY OF THE INVENTION The present invention solves the problem that it is difficult to release hydrogen because the stability of the magnesium-rare earth hydrogen storage alloy with hydrogen is too high, and the hydrogen storage alloy has a large discharge capacity. An object of the present invention is to provide a hydrogen storage alloy capable of easily realizing an electrode.

Another object of the present invention is to provide a hydrogen storage alloy having improved hydrogen storage and release characteristics.

Further, the present invention aims at providing a secondary battery having a negative electrode containing the above-mentioned hydrogen storage alloy, having a high capacity and an excellent charge / discharge cycle life.

[0018]

According to the present invention, there is provided an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (1), or a crushed product of the alloy ingot. There is provided a hydrogen storage alloy, comprising:

(Mg _{1 -ab} R _{1 a} M _{1 b} ) Ni _z (1) where R 1 is at least one element selected from rare earth elements including Y, and M 1 is an element having a higher electronegativity than Mg (provided that , The element of R1, Cr, Mn, Fe,
At least one element selected from the group consisting of Co, Cu, Zn and Ni), a, b and z are each 0.1 ≦ a ≦
0.8, 0 <b ≦ 0.9, 1−ab> 0, 3 ≦ z ≦
Defined as 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (2) or a pulverized product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _1−a R1 _a (Ni _1−x M2 _x ) _z (2) where R1 is at least one element selected from rare earth elements including Y, and M2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, a, x
And z are respectively 0.1 ≦ a ≦ 0.8 and 0 <x ≦ 0.
9, 3 ≦ z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (3) or a crushed product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _{1 -ab} R _{1 a} M _{1 b} (Ni _{1 -x} M 2 _x ) _z (3) where R 1 is at least one element selected from rare earth elements including Y, M 2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, M1 is an element having a higher electronegativity than Mg (provided that the R1
, A, b, x, and z are at least 0.1 ≦ a ≦ 0.8, 0 <b ≦ 0.9, 1-a -B>
0, 0 <x ≦ 0.9 and 3 ≦ z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (4) or a pulverized product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _1-a R1 _a (Ni _1-x M3 _x ) _z (4) where R1 is at least one element selected from rare earth elements including Y, and M3 is Co, Mn, Fe, Al, G
a, at least one element selected from Zn, Sn, Cu, Si and B, wherein a, x and z are each 0.6
It is defined as 5 ≦ a ≦ 0.8, 0 <x ≦ 0.6, and 3 ≦ z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (5) or a pulverized product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _{1 -ab} R _{1 a} T 1 _b (Ni _{1 -x} M 3 _x ) _z (5) where R 1 is at least one element selected from rare earth elements including Y, T 1 is Ca, Ti, Zr and At least one element selected from Hf, M3 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si and B are at least one element selected from the group consisting of a, b, x, and z of 0.65 ≦ a <0.8 and 0 <b ≦ 0, respectively. .3,
0.65 <(a + b) ≦ 0.8, 0 <x ≦ 0.6, 3 ≦
It is defined as z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (6) or a pulverized product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _a R _{1 1-a} (Ni _1-xy Co _x M4 _y ) _z (6) where R1 is at least one element selected from rare earth elements including Y, M4 is Mn, Fe, V, Cr, N
b, at least one element selected from Al, Ga, Zn, Sn, Cu, Si, P and B, wherein a, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0 <x ≦ 0.
5, 0 ≦ y ≦ 0.2, 3 ≦ z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (7) or a crushed product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _a R _{11 -ab} T 2 _b (Ni _{1 -xy} Co _x M 4 _y ) _z (7) where R 1 is at least one element selected from rare earth elements containing Y, and T 2 is Ca, Ti and Zr At least one element selected from the group consisting of Mn, Fe, V, C
r, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B are at least one element selected from the group consisting of a,
b, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0
<B ≦ 0.3, 0 <x ≦ 0.5, 0 ≦ y ≦ 0.2, 3 ≦
It is defined as z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (8) or a pulverized product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _a (La _{1 -b} R _{1 b} ) _{1 -a} Ni _z (8) where R 1 is at least one element selected from rare earth elements containing Y, and is not La but a, b And z are 0.2 ≦ a ≦ 0.35 and 0.01 ≦ b <, respectively.
0.5, 3 ≦ z ≦ 3.8.

According to the present invention, an alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (9) or a crushed product of the alloy ingot is included. A hydrogen storage alloy is provided.

Mg _a (La _1−b R1 _b ) _1−a (Ni _1−x M3 _x ) _z (9) where R1 is at least one element selected from rare earth elements including Y, and Not La, M3 is C
o, Mn, Fe, Al, Ga, Zn, Sn, Cu, Si
And at least one element selected from B and a,
b, x and z are 0.2 ≦ a ≦ 0.35 and 0.0, respectively.
1 ≦ b <0.5, 0.1 ≦ x ≦ 0.6, 3 ≦ z ≦ 3.8
Is defined as

According to the present invention, there is provided a hydrogen storage alloy comprising an alloy having a composition represented by the following general formula (10).

Mg _a R 2 _1-ab T1 _b (Ni _1-x M3 _x ) _z (10) where R 2 is at least two elements selected from rare earth elements including Y, and the Ce content of R 2 Is 20% by weight
T1 is at least one element selected from Ca, Ti, Zr and Hf, and M3 is Mn, Fe, C
at least one element selected from the group consisting of o, Al, Ga, Zn, Sn, Cu, Si and B, a, b, x and z
Are respectively 0 <a ≦ 0.5, 0 ≦ b ≦ 0.3, 0 ≦ x
≦ 0.9 and 3 ≦ z <4.

According to the present invention, there is provided a hydrogen storage alloy comprising an alloy having a composition represented by the following general formula (11).

Mg _a R 3 _1-ab T1 _b (Ni _1-xy M5 _x Co _y ) _z (11) where R3 is at least two elements selected from rare earth elements containing Y, and Ce of R3 is The content is less than m wt%, m is represented by m = 125y + 20 (y is the amount of Co in the formula (11)), and T1 is at least one element selected from Ca, Ti, Zr and Hf. And M5
Is at least one element selected from Mn, Fe, Al, Ga, Zn, Sn, Cu, Si and B;
b, x, y and z are respectively 0 <a ≦ 0.5, 0 ≦ b
≦ 0.3, 0 ≦ x ≦ 0.9, 0 <y ≦ 0.4, x + y ≦
0.9, 3 ≦ z <4.

According to the present invention, it has a composition represented by the following general formula (12), wherein a and z in the general formula (12) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2) is provided as a main phase, and a hydrogen storage alloy comprising an alloy having 20 or less plane defects per 100 nm in the main phase is provided.

Mg _a R _{1 1 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (12) where R 1 is at least one element selected from rare earth elements including Y, T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, it has a composition represented by the following general formula (13), wherein a and z in the general formula (13) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2) and 70% by volume of crystal grains having a plane defect of 20 or less per 100 nm as a main phase.
A hydrogen storage alloy characterized by including an alloy containing more than 1%.

Mg _a R _{1 1 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (13) where R 1 is at least one element selected from rare earth elements including Y, T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, it has a composition represented by the following general formula (14), wherein a and z in the general formula (14) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2), and a phase satisfying CaCu
_{When the} crystal phase having a type ₅ crystal structure is 20% by volume or less,
There is provided a hydrogen storage alloy comprising an alloy having a crystal phase having a Cu ₂ type crystal structure of 10% by volume or less.

Mg _a R _{1 1 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (14) where R 1 is at least one element selected from rare earth elements including Y, T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, the main phase is represented by the following general formula (15) and the main phase is Ce ₂ Ni ₇ type, CeNi ₃ type, Gd
_At least one selected from phases having a crystal structure of either ₂ Co ₇ type or PuNi ₃ type or a similar crystal structure
There is provided a hydrogen storage alloy comprising a three phase alloy.

R1 _1-ab Mg _a T2 _b (Ni _1-x M7 _x ) _z (15) where R1 is at least one element selected from rare earth elements including yttrium, and T2 is Ca, Ti, Zr At least one selected element, M7 is Co, Mn,
Fe, V, Cr, Nb, Al, Ga, Zn, Sn, C
at least one element selected from u, Si, P, and B, and a, b, x, and z are each 0 <a ≦ 0.6, 0 ≦
It is defined as b ≦ 0.5, 0 ≦ x ≦ 0.9, 2.5 ≦ z <4.5.

According to the present invention, the intensity (I ₁ ) of the strongest peak represented by the following general formula (16) and appearing in the range of 2θ = 8 to 13 ° in the X-ray diffraction pattern using CuKα ray: A hydrogen storage alloy is provided which includes an alloy having an intensity ratio (I ₁ / I ₂ ) of the intensity of the strongest line peak of all peaks (I ₂ ) to less than 0.15.

R4 _1-ab Mg _a M8 _b (Ni _1-x M9 _x ) _z (16) where R4 is a rare earth element containing yttrium and C
at least one element selected from a, M8 is an element having a higher electronegativity than Mg (except for R4, Ni and M9), and M9 is Co, Mn, Fe, V, Cr, Nb, A
1, at least one element selected from Ga, Zn, Sn, Cu, Si, P, and B, where a, b, x, and z are respectively 0 <a ≦ 0.6, 0 ≦ b ≦ 0.5, 0 ≦ x ≦ 0.
9, 2.5 ≦ z <4.5.

According to the present invention, the A ₂ B ₄ subcell and AB ₅
(Where A is the heat of formation of hydride ΔH (kJ /
(mol) is less than 20 kJ / mol, and B has the heat of formation ΔH (kJ / mol) of 20 kJ / mol.
mol or more of one or more elements) and AB
A hydrogen storage alloy is provided, comprising a crystal phase composed of unit cells in which the ratio X of the number of A ₂ B ₄ subcells to the number of ₅ subcells is 0.5 <X <1.

Further, according to the present invention, a negative electrode produced by a casting method or a sintering method and containing hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (1): And a secondary battery provided with:

(Mg _{1 -ab} R _{1 a} M _{1 b} ) Ni _z (1) wherein R 1 is at least one element selected from rare earth elements including Y, and M 1 is an element having a higher electronegativity than Mg (provided that , The element of R1, Cr, Mn, Fe,
At least one element selected from the group consisting of Co, Cu, Zn and Ni), a, b and z are each 0.1 ≦ a ≦
0.8, 0 <b ≦ 0.9, 1−ab> 0, 3 ≦ z ≦
Defined as 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (2). A secondary battery is provided.

Mg _1-a R1 _a (Ni _1-x M2 _x ) _z (2) where R1 is at least one element selected from rare earth elements including Y, and M2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, a, x
And z are respectively 0.1 ≦ a ≦ 0.8 and 0 <x ≦ 0.
9, 3 ≦ z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (3). A secondary battery is provided.

Mg _{1 -ab} R _{1 a} M _{1 b} (Ni _{1 -x} M 2 _x ) _z (3) where R 1 is at least one element selected from rare earth elements including Y, M 2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, M1 is an element having a higher electronegativity than Mg (provided that the R1
, A, b, x, and z are at least 0.1 ≦ a ≦ 0.8, 0 <b ≦ 0.9, 1-a -B>
0, 0 <x ≦ 0.9 and 3 ≦ z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (4). A secondary battery is provided.

Mg _1−a R1 _a (Ni _1−x M3 _x ) _z (4) where R1 is at least one element selected from rare earth elements including Y, and M3 is Co, Mn, Fe, Al, G
a, at least one element selected from Zn, Sn, Cu, Si and B, wherein a, x and z are each 0.6
It is defined as 5 ≦ a ≦ 0.8, 0 <x ≦ 0.6, and 3 ≦ z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (5). A secondary battery is provided.

Mg _{1 -ab} R _{1 a} T 1 _b (Ni _{1 -x} M 3 _x ) _z (5) where R 1 is at least one element selected from rare earth elements including Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M3 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si and B are at least one element selected from the group consisting of a, b, x, and z of 0.65 ≦ a <0.8 and 0 <b ≦ 0, respectively. .3,
0.65 <(a + b) ≦ 0.8, 0 <x ≦ 0.6, 3 ≦
It is defined as z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (6). A secondary battery is provided.

Mg _a R _{1 1-a} (Ni _1-xy Co _x M4 _y ) _z (6) where R1 is at least one element selected from rare earth elements including Y, M4 is Mn, Fe, V, Cr, N
b, at least one element selected from Al, Ga, Zn, Sn, Cu, Si, P and B, wherein a, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0 <x ≦ 0.
5, 0 ≦ y ≦ 0.2, 3 ≦ z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen-absorbing alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (7). A secondary battery is provided.

Mg _a R _{11 -ab} T 2 _b (Ni _{1 -xy} Co _x M 4 _y ) _z (7) where R 1 is at least one element selected from rare earth elements containing Y, and T 2 is Ca, Ti and Zr At least one element selected from the group consisting of Mn, Fe, V, C
r, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B are at least one element selected from the group consisting of a,
b, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0
<B ≦ 0.3, 0 <x ≦ 0.5, 0 ≦ y ≦ 0.2, 3 ≦
It is defined as z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (8). A secondary battery is provided.

Mg _a (La _{1 -b} R _{1 b} ) _{1 -a} Ni _z (8) where R 1 is at least one element selected from rare earth elements including Y, and is not La but a, b And z are 0.2 ≦ a ≦ 0.35 and 0.01 ≦ b <, respectively.
0.5, 3 ≦ z ≦ 3.8.

According to the present invention, there is provided a negative electrode which is produced by a casting method or a sintering method and contains hydrogen storage alloy particles containing a pulverized alloy ingot having a composition represented by the following general formula (9). A secondary battery is provided.

Mg _a (La _1−b R1 _b ) _1−a (Ni _1−x M3 _x ) _z (9) where R1 is at least one element selected from rare earth elements including Y, and Not La, M3 is C
o, Mn, Fe, Al, Ga, Zn, Sn, Cu, Si
And at least one element selected from B and a,
b, x and z are 0.2 ≦ a ≦ 0.35 and 0.0, respectively.
1 ≦ b <0.5, 0.1 ≦ x ≦ 0.6, 3 ≦ z ≦ 3.8
Is defined as

According to the present invention, there is provided a secondary battery comprising a negative electrode containing a hydrogen storage alloy containing an alloy having a composition represented by the following general formula (10).

Mg _a R 2 _1-ab T1 _b (Ni _1-x M3 _x ) _z (10) where R 2 is at least two elements selected from rare earth elements including Y, and the Ce content of R 2 Is 20% by weight
T1 is at least one element selected from Ca, Ti, Zr and Hf, and M3 is Mn, Fe, C
at least one element selected from the group consisting of o, Al, Ga, Zn, Sn, Cu, Si and B, a, b, x and z
Are respectively 0 <a ≦ 0.5, 0 ≦ b ≦ 0.3, 0 ≦ x
≦ 0.9 and 3 ≦ z <4.

According to the present invention, there is provided a secondary battery including a negative electrode containing a hydrogen storage alloy containing an alloy having a composition represented by the following general formula (11).

Mg _a R 3 _1-ab T1 _b (Ni _1-xy M5 _x Co _y ) _z (11) where R 3 is at least two elements selected from rare earth elements containing Y, and Ce of R 3 The content is less than m wt%, m is represented by m = 125y + 20 (y is the amount of Co in the formula (11)), and T1 is at least one element selected from Ca, Ti, Zr and Hf. And M5
Is at least one element selected from Mn, Fe, Al, Ga, Zn, Sn, Cu, Si and B;
b, x, y and z are respectively 0 <a ≦ 0.5, 0 ≦ b
≦ 0.3, 0 ≦ x ≦ 0.9, 0 <y ≦ 0.4, x + y ≦
0.9, 3 ≦ z <4.

According to the present invention, it has a composition represented by the following general formula (12), wherein a and z in the general formula (12) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2), and a negative electrode containing a hydrogen storage alloy containing an alloy in which the number of plane defects in the main phase is 20 or less per 100 nm. A secondary battery is provided.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (12) where R 1 is at least one element selected from rare earth elements including Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, it has a composition represented by the following general formula (13), wherein a and z in the general formula (13) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2) and 70% by volume of crystal grains having a plane defect of 20 or less per 100 nm as a main phase.
A secondary battery is provided, comprising a negative electrode containing a hydrogen storage alloy containing an alloy containing more than.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (13) where R 1 is at least one element selected from rare earth elements containing Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, it has a composition represented by the following general formula (14), wherein a and z in the general formula (14) are z = −6 × a + δ (δ is 5-0.2 ≦ δ ≦ 5 +
0.2), and a phase satisfying CaCu
_{When the} crystal phase having a type ₅ crystal structure is 20% by volume or less,
A secondary battery is provided, comprising a negative electrode containing a hydrogen storage alloy containing an alloy having a crystal phase having a Cu ₂ type crystal structure of 10% by volume or less.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (14) where R 1 is at least one element selected from rare earth elements including Y, T 1 is Ca, Ti, Zr, At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

According to the present invention, the main phase is represented by the following general formula (15) and the main phase is Ce ₂ Ni ₇ type, CeNi ₃ type, Gd
_At least one selected from phases having a crystal structure of either ₂ Co ₇ type or PuNi ₃ type or a similar crystal structure
A secondary battery is provided, comprising a negative electrode containing a hydrogen storage alloy containing an alloy that is one phase.

R1 _1-ab Mg _a T2 _b (Ni _1-x M7 _x ) _z (15) where R1 is at least one element selected from rare earth elements including yttrium, and T2 is Ca, Ti, Zr At least one selected element, M7 is Co, Mn,
Fe, V, Cr, Nb, Al, Ga, Zn, Sn, C
at least one element selected from u, Si, P, and B, and a, b, x, and z are each 0 <a ≦ 0.6, 0 ≦
It is defined as b ≦ 0.5, 0 ≦ x ≦ 0.9, 2.5 ≦ z <4.5.

According to the present invention, the intensity (I ₁ ) of the strongest peak represented by the following general formula (16) and appearing in the range of 2θ = 8 to 13 ° in the X-ray diffraction pattern using CuKα ray: A _secondary comprising a negative electrode containing a hydrogen storage alloy including an alloy having an intensity ratio (I ₁ / I ₂ ) of the intensity (I ₂ ) of the strongest line peak of all peaks to less than 0.15. A battery is provided.

R4 _1-ab Mg _a M8 _b (Ni _1-x M9 _x ) _z (16) where R4 is a rare earth element containing yttrium and C
at least one element selected from a, M8 is an element having a higher electronegativity than Mg (except for R4, Ni and M9), and M9 is Co, Mn, Fe, V, Cr, Nb, A
1, at least one element selected from Ga, Zn, Sn, Cu, Si, P, and B, where a, b, x, and z are respectively 0 <a ≦ 0.6, 0 ≦ b ≦ 0.5, 0 ≦ x ≦ 0.
9, 2.5 ≦ z <4.5.

According to the present invention, A ₂ B ₄ subcell and AB ₅
(Where A is the heat of formation of hydride ΔH (kJ /
(mol) is less than 20 kJ / mol, and B has the heat of formation ΔH (kJ / mol) of 20 kJ / mol.
mol or more of one or more elements) and AB
A secondary battery comprising a negative electrode containing a hydrogen storage alloy containing a crystal phase comprising a unit cell in which the ratio X of the number of A ₂ B ₄ subcells to the number of ₅ subcells is 0.5 <X <1. Is provided.

[0084]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Fourteen kinds of hydrogen storage alloys according to the present invention will be described below.

(A) First Hydrogen Storage Alloy This hydrogen storage alloy is produced by a casting method or a sintering method, and has the composition represented by the following general formula (1). Including pulverized material.

(Mg _{1 -ab} R _{1 a} M _{1 b} ) Ni _z (1) where R 1 is at least one element selected from rare earth elements including Y, and M 1 is an element having a higher electronegativity than Mg (provided that , The element of R1, Cr, Mn, Fe,
At least one element selected from the group consisting of Co, Cu, Zn and Ni), a, b and z are each 0.1 ≦ a ≦
0.8, 0 <b ≦ 0.9, 1−ab> 0, 3 ≦ z ≦
Defined as 3.8.

From the viewpoint of reducing the cost of the hydrogen storage alloy, La, Ce, Pr, Nd and Y are used as the element R1.
It is preferably at least one element selected from Among them, misch metal which is a mixture of rare earth elements is preferable. As the misch metal, La, C
An alloy having a content of e, Pr and Nd of at least 99% by weight is desirable. Specifically, when the Ce content is 50% by weight or more,
Ce-rich misch metal (Mm) having a La content of 30% by weight or less, and La-rich misch metal (Lm) having a La content higher than that of Mm can be given.

The substitution amount (a) of R1 in the Mg component is defined in the above range for the following reason. If the substitution amount (a) is less than 0.1, it may be difficult to increase the hydrogen storage rate of the alloy. On the other hand, if the substitution amount (a) exceeds 0.8, it may be difficult to improve the effective hydrogen storage amount of the alloy, and the original characteristics of the Mg-based alloy may be impaired. The replacement amount (a)
Of these, a more preferred range is 0.35 ≦ a ≦ 0.8.

As M1 described above, for example, Al:
1.5, Ta: 1.5, V: 1.6, Nb: 1.6, G
a: 1.6, In: 1.7, Ge: 1.8, Pb: 1.
8, Mo 1.8, Sn: 1.8, Si: 1.8, Re:
1.9, Ag: 1.9, B: 2.0, C: 2.5, P:
2.1, Ir: 2.2, Rh: 2.2, Ru: 2.2,
Os: 2.2, Pt: 2.2, Au: 2.4, Se:
2.4, S: 2.5. As M1, one or more kinds selected from these elements can be used. For each element, the number after: indicates the electronegativity of the metal using the value of Pauling. In addition,
The electronegativity when using the value of Mg poling is
1.2.

The amount of Mg described above in M1 (0 <b
≦ 0.9) substitution can increase the hydrogen equilibrium pressure of the alloy. As a result, the alkaline secondary battery provided with the negative electrode containing the alloy can improve the operating voltage, so that the discharge capacity and the cycle life can be improved.

Further, such an alloy can improve the hydrogen storage / release speed. This is presumed to be due to the following mechanism. That is, in general, in many hydrides of a single metal, a correlation is established that the larger the difference in electronegativity between metal and hydrogen, the larger the bonding force. Considering how the bonding force between the alloy and hydrogen changes by replacing the component of Mg with a different element from the viewpoint of electronegativity, the larger the difference in electronegativity with hydrogen is, the more the metal-hydrogen difference It is thought that the ionic bondability during the bonding becomes stronger, the bonding becomes stronger, and the stored hydrogen becomes more stable. Therefore, by making M1 an element having a higher electronegativity than Mg, the difference in electronegativity between the hydrogen-absorbing alloy and hydrogen can be reduced, thereby destabilizing hydrogen in the crystal lattice of the alloy. It is speculated that this can be done. As a result, the storage / release characteristics of the hydrogen storage alloy can be improved.

In particular, by using Al or Ag or both as the M1 component, the crystal lattice of the hydrogen storage alloy can be expanded, so that the storage / release characteristics can be further improved.

Further, the substitution amount b of M1 in the Mg component is 0.
If it exceeds 9, the crystal structure of the hydrogen-absorbing alloy will be remarkably changed, and the inherent properties of the Mg-based alloy may be impaired. In addition, such a hydrogen storage alloy may have a significantly low catalytic activity during storage. A more preferred range of the substitution amount b is 0.1 ≦ b ≦ 0.8.

The Ni content in the alloy (z)
Is defined in the above range for the following reason. When the content (z) is less than 3.0, the hydrogen in the alloy is extremely stabilized, so that the amount of hydrogen released from the alloy decreases. On the other hand, when the content (z) exceeds 3.8,
There is a possibility that the number of hydrogen sites in the alloy is reduced and the hydrogen storage amount is reduced. A more preferable range of the content (z) is 3.
The range is 0 ≦ z ≦ 3.6.

The first hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The first hydrogen storage alloy is manufactured by a casting method or a sintering method. Hereinafter, these methods will be described.

(Casting Method) (a) Each element is weighed, and is subjected to high frequency induction melting in an inert gas, for example, an argon atmosphere, and then cast into a mold or the like to obtain an alloy ingot of a target composition.

(B) RNi ₅ system, R ₂ Ni ₇ system, RNi
₃ system, RNi ₂ system, Mg ₂ Ni-based, produced by high-frequency induction melting a master alloy such MgNi ₂ system. Each of the obtained master alloys is weighed so as to have a desired composition, is subjected to high frequency induction melting, and is cast into a mold or the like to obtain an alloy ingot of the desired composition.

(Sintering Method) (a) Each element is weighed, sintered in an inert gas atmosphere, for example, an argon atmosphere, and then heat-treated near its melting point to obtain an alloy ingot of a target composition.

(B) RNi ₅ system, R ₂ Ni ₇ system, RNi
₃ system, RNi ₂ system, to produce a relatively high melting point master alloy such as RNi system, Mg ₂ Ni-based, by a high frequency induction melting a master alloy such MgNi ₂ system. The obtained powders of the respective master alloys are weighed so as to have a desired composition, and heat-treated at around the melting point to obtain an alloy ingot of the desired composition.

It is preferable that the alloy thus obtained is subjected to a heat treatment in a vacuum or an inert atmosphere at a temperature of 300 ° C. or higher and lower than the melting point for 0.1 to 500 hours. By performing such a heat treatment, the lattice distortion of the alloy can be reduced, so that the hydrogen storage / release characteristics such as the hydrogen storage / release speed can be improved. The temperature of the heat treatment is preferably 750 to 1050C, and more preferably 800 to 1000C. The heat treatment time is preferably 0.5 to 100 hours, more preferably 1 to 20 hours.

(B) Second hydrogen storage alloy This alloy is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the following general formula (2) or a pulverization of the alloy ingot. Including things.

Mg _1−a R1 _a (Ni _1−x M2 _x ) _z (2) where R1 is at least one element selected from rare earth elements including Y, and M2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, a, x
And z are respectively 0.1 ≦ a ≦ 0.8 and 0 <x ≦ 0.
9, 3 ≦ z ≦ 3.8.

As the element R1 of this alloy, the same elements as those described for the first alloy can be used.

The substitution amount (a) of R1 in the Mg component is defined in the above range for the following reason. If the substitution amount (a) is less than 0.1, it may be difficult to improve the hydrogen release characteristics of the alloy. On the other hand, if the substitution amount (a) exceeds 0.8, it may be difficult to improve the effective hydrogen storage amount of the alloy, and the original characteristics of the Mg-based alloy may be impaired. A more preferable range of the substitution amount (a) is 0.65 ≦ a ≦ 0.80.
It is.

By substituting the Ni component of the alloy with the above-mentioned amount (0 <x ≦ 0.9) with the M2, the hydrogen storage / release rate of the alloy can be improved. This is presumed to be due to the fact that M2 is an element that does not exothermically react with hydrogen, that is, an element that does not spontaneously form a hydride, and that the addition and storage of M2 facilitates the storage and release of the hydrogen storage alloy. Is done. In addition, an alkaline secondary battery provided with a negative electrode containing the alloy can dramatically improve cycle characteristics. It is preferable that M2 is made of Co, Mn, or both Co and Mn.

When the substitution amount x of M2 in the Ni component is 0.
If it exceeds 9, the crystal structure of the hydrogen storage alloy will be remarkably changed, and the original characteristics of the Mg-based alloy will be impaired. The substitution amount (x) is preferably set to 0.1 ≦ x ≦ 0.8.

The content (z) of the Ni.M2 component in the alloy is defined in the above range for the following reason. When the content (z) is less than 3.0,
Because the hydrogen in the alloy is much more stable, the hydrogen release of the alloy is reduced. On the other hand, if the content (z) exceeds 3.8, the number of hydrogen sites in the alloy may decrease, and the hydrogen storage amount may decrease. A more preferable range of the content (z) is 3.0 ≦ z ≦ 3.6.

The second hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The second hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(C) Third Hydrogen Storage Alloy This alloy is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the following general formula (3), or a crushed alloy ingot. Including things.

Mg _{1 -ab} R _{1 a} M _{1 b} (Ni _{1 -x} M 2 _x ) _z (3) where R 1 is at least one element selected from rare earth elements including Y, and M 2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, M1 is an element having a higher electronegativity than Mg (provided that the R1
, A, b, x, and z are at least 0.1 ≦ a ≦ 0.8, 0 <b ≦ 0.9, 1-a -B>
0, 0 <x ≦ 0.9 and 3 ≦ z ≦ 3.8.

As the element R1 of this alloy, the same elements as described in the first alloy can be used.

The substitution amount (a) of R1 in the Mg component is defined in the above range for the following reason. If the substitution amount (a) is less than 0.1, it may be difficult to improve the hydrogen storage rate of the alloy. On the other hand, if the substitution amount (a) exceeds 0.8, it may be difficult to improve the effective hydrogen storage amount of the alloy, and the original characteristics of the Mg-based alloy may be impaired. A more preferable range of the substitution amount (a) is 0.35 ≦ a ≦ 0.
8

As the element M1 of this alloy, for example, the same element as described in the first alloy can be used. Further, the M1 includes Al or A
g, or both. Such a hydrogen storage alloy containing M1 can expand the crystal lattice of the hydrogen storage alloy, so that the storage / release characteristics can be further improved.

The hydrogen equilibrium pressure of the alloy can be increased by setting the substitution amount (b) of M1 in the Mg component within the above range. As a result, the alkaline secondary battery provided with the negative electrode containing the alloy can improve the operating voltage, so that the discharge capacity and the cycle life can be improved. Further, such an alloy can improve the hydrogen storage / release speed. On the other hand, when the substitution amount b of M1 in the Mg component exceeds 0.9, the crystal structure of the hydrogen storage alloy changes remarkably, and the original characteristics of the Mg-based alloy are impaired. In addition, such hydrogen storage alloys have significantly reduced catalytic activity during storage. A more preferable range of the substitution amount b is 0.
1 ≦ b ≦ 0.8.

By substituting the Ni component of the alloy with the M2 in the amount described above (0 <x ≦ 0.9), the hydrogen storage / release rate of the alloy can be improved. Also,
The alkaline secondary battery including the negative electrode containing the alloy can dramatically improve the cycle characteristics. On the other hand, Ni
When the substitution amount x of M2 in the component exceeds 0.9, the crystal structure of the hydrogen storage alloy changes significantly, and the original characteristics of the Mg-based alloy are impaired. M2 is Co or M
Preferably, n or both elements are used. A more preferable range of the substitution amount x is 0.1 ≦ x ≦ 0.8.

The content (z) of the Ni.M2 component in the alloy is defined in the above range for the following reason. When the content (z) is less than 3.0,
Because the hydrogen in the alloy is much more stable, the hydrogen release of the alloy is reduced. On the other hand, if the content (z) exceeds 3.8, the number of hydrogen sites in the alloy may decrease, and the hydrogen storage amount may decrease. A more preferable range of the content (z) is 3.0 ≦ z ≦ 3.6.

The third hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

This third hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(D) Fourth Hydrogen Storage Alloy This fourth hydrogen storage alloy is prepared by a casting method or a sintering method and has an alloy ingot having a composition represented by the following general formula (4), or Includes a crushed product of the alloy ingot.

Mg _1-a R1 _a (Ni _1-x M3 _x ) _z (4) where R1 is at least one element selected from rare earth elements including Y, M3 is Co, Mn, Fe, Al, G
a, at least one element selected from Zn, Sn, Cu, Si and B, wherein a, x and z are each 0.6
It is defined as 5 ≦ a ≦ 0.8, 0 <x ≦ 0.6, and 3 ≦ z ≦ 3.8.

As R1 in the above formula (4), the same as those described for the first hydrogen storage alloy can be used.

The reason why the amount (a) of R1 is specified in the above range is as follows. When the substitution amount (a) is less than 0.65, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease. On the other hand, if the substitution amount (a) exceeds 0.8, it may be difficult to enhance the hydrogen release characteristics of the alloy.

In the above formula (4), the substitution element M3 for Ni is Co, Mn, Fe, Al, Ga, Zn,
By using at least one selected from Sn, Cu, Si and B, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is presumed to be due to the fact that M3 is an element that does not exothermically react with hydrogen, that is, an element that does not spontaneously produce hydride, and that the replacement of M3 facilitates the storage and release of the hydrogen storage alloy. Is done. In addition, a metal oxide / hydrogen secondary battery provided with a negative electrode containing the alloy can significantly improve cycle characteristics.

In the above formula (4), when the substitution amount (x) of M3 to Ni exceeds 0.6, the discharge capacity of a metal oxide / hydrogen secondary battery provided with a negative electrode containing such an alloy is reduced. descend. A more preferred range of the substitution amount (x) is 0.1.
01 ≦ x ≦ 0.5.

(Mg + R) and (N
The reason why the ratio (z) of (i + M3) is specified in the above range is as follows. When the ratio (z) is less than 3.0, hydrogen in the alloy is extremely stabilized, and the amount of hydrogen released from the alloy is reduced. By setting the ratio (z) to 3 or more, it is possible to sufficiently improve the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy, and to improve the discharge capacity and cycle characteristics of the metal oxide. -A hydrogen secondary battery can be realized. However, if the ratio (z) exceeds 3.8, the number of hydrogen sites in the alloy may decrease, and the amount of hydrogen occlusion may decrease. A more preferable range of the ratio (z) is a range of 3.0 ≦ z ≦ 3.6.

The fourth hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The fourth hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as described in the first hydrogen storage alloy.

(E) Fifth hydrogen storage alloy This alloy is manufactured by a casting method or a sintering method and has a composition represented by the following general formula (5). Including things.

Mg _{1 -ab} R _{1 a} T 1 _b (Ni _{1 -x} M 3 _x ) _z (5) where R 1 is at least one element selected from rare earth elements containing Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M3 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si and B are at least one element selected from the group consisting of a, b, x, and z of 0.65 ≦ a <0.8 and 0 <b ≦ 0, respectively. .3,
0.65 <(a + b) ≦ 0.8, 0 <x ≦ 0.6, 3 ≦
It is defined as z ≦ 3.8.

As R1 in the above formula (5), the same ones as described in the first hydrogen storage alloy can be used.

The reason why the amount (a) of R1 is defined in the above range is as follows. When the substitution amount (a) is less than 0.65, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease. On the other hand, when the substitution amount (a) is 0.8 or more, it may be difficult to enhance the hydrogen release characteristics of the alloy.

The substitution element T1 for Mg is replaced by Ca, T
By using at least one element selected from i, Zr and Hf, it is possible to improve the characteristics such as the hydrogen desorption rate without remarkably reducing the hydrogen storage capacity of the alloy, and to improve the hydrogen storage and release characteristics. It is possible to suppress the pulverization of the alloy.

When the substitution amount (b) of T1 exceeds 0.3, the above-mentioned effects, namely, the improvement of the emission characteristics and the suppression of the pulverization cannot be observed, and the negative electrode containing the alloy is provided. The discharge capacity and cycle life of the secondary battery decrease. A smaller cycle amount (b) tends to obtain a longer cycle life. From the viewpoint of ensuring a long life, the replacement amount (b) of the T1 is preferably set to 0.2 or less.

In the formula (5), the substitution amount (a)
The reason for defining the sum (a + b) of the above and the replacement amount (b) in the above range is as follows. Sum (a + b)
If is set to 0.65 or less, the crystal structure of the alloy changes, and the amount of hydrogen occlusion may decrease. On the other hand, if the sum (a + b) exceeds 0.8, it may be difficult to enhance the hydrogen release characteristics of the alloy.

In the above formula (5), the substituting element M3 for Ni is Co, Mn, Fe, Al, Ga, Zn,
By using at least one selected from Sn, Cu, Si and B, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is presumed to be due to the fact that M3 is an element that does not exothermically react with hydrogen, that is, an element that does not spontaneously produce hydride, and that the replacement of M3 facilitates the storage and release of the hydrogen storage alloy. Is done. In addition, a metal oxide / hydrogen secondary battery provided with a negative electrode containing the alloy can significantly improve cycle characteristics.

In the above formula (5), when the substitution amount (x) of M3 to Ni exceeds 0.6, the discharge capacity of a metal oxide / hydrogen secondary battery provided with a negative electrode containing such an alloy is reduced. May drop. A more preferable range of the substitution amount (x) is 0.01 ≦ x ≦ 0.5.

The ratio (z) between (Mg + R + T) and (Ni + M) in the above equation (5) is defined in the above range for the following reason. When the ratio (z) is less than 3.0, hydrogen in the alloy is extremely stabilized, and the amount of hydrogen released from the alloy is reduced. By setting the ratio (z) to 3 or more, it is possible to sufficiently improve the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy, and to improve the discharge capacity and cycle characteristics of the metal oxide. -A hydrogen secondary battery can be realized. However, if the ratio (z) exceeds 3.8, the number of hydrogen sites in the alloy may decrease, and the amount of hydrogen occlusion may decrease. A more preferable range of the ratio (z) is a range of 3.0 ≦ z ≦ 3.6.

Further, the fifth hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The fifth hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(F) Sixth hydrogen storage alloy This alloy is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the following general formula (6) or a pulverization of the alloy ingot. Including things.

[0147] Mg _a R1 _1-a except _{(Ni 1-xy Co x M4} y) z (6), R1 is at least one element selected from rare earth elements including Y, M4 is Mn, Fe, V, Cr, N
b, at least one element selected from Al, Ga, Zn, Sn, Cu, Si, P and B, wherein a, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0 <x ≦ 0.
5, 0 ≦ y ≦ 0.2, 3 ≦ z ≦ 3.8.

As R1 in the above formula (6), the same as those described for the first hydrogen storage alloy can be used.

The amount (a) of Mg is defined in the above range for the following reason. If the amount (a) of Mg is less than 0.2, it may be difficult to enhance the hydrogen release characteristics of the alloy. On the other hand, when the amount (a) of Mg is 0.
If it exceeds 35, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease.

By setting the amount of Co in the above range,
The reversibility in the storage and release of hydrogen can be improved, and the cycle characteristics of the secondary battery can be significantly improved. In addition, the alloy has a small plateau slope, can reduce hysteresis, and can improve static hydrogen storage characteristics. On the other hand, if the Co amount (x) exceeds 0.5, the hydrogen storage amount may decrease, and when a secondary battery is formed from a negative electrode containing the alloy, an oxidation / reduction reaction of Co occurs. , It may be difficult to obtain a large discharge capacity. A more preferable range of the Co amount (x) is 0.03 ≦ x ≦ 0.35.

In the above-mentioned formula (6), Mn, Fe, V, Cr, Nb, Al, G
By using at least one selected from a, Zn, Sn, Cu, Si, P, and B, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is presumed to be due to the diffusion of hydrogen that has entered the alloy due to the substitution of M4, and the easy absorption and release of hydrogen. In addition, a metal oxide / hydrogen secondary battery provided with a negative electrode containing the alloy can significantly improve cycle characteristics.

When the amount (y) of M4 exceeds 0.2, the metal oxide having a negative electrode containing such an alloy has
The discharge capacity of the hydrogen secondary battery may be reduced. The M
A more preferable range of the amount (y) of 0.01 is 0.01 ≦ y ≦ 0.
Fifteen.

The ratio (z) between (Mg + R) and (Ni + Co + M) is defined in the above range for the following reason. When the ratio (z) is less than 3.0, hydrogen in the alloy is extremely stabilized, and the amount of hydrogen released from the alloy is reduced. By making the ratio (z) 3 or more,
The hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be sufficiently improved, and a metal oxide / hydrogen secondary battery with improved discharge capacity and cycle characteristics can be realized. However, when the ratio (z) is 3.8 or more, the number of hydrogen sites in the alloy may decrease, and the hydrogen storage amount may decrease. A more preferable range of the ratio (z) is a range of 3.0 ≦ z ≦ 3.6.

The sixth hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

This sixth hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(G) Seventh hydrogen storage alloy This alloy is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the following general formula (7), or a crushed alloy ingot. Including things.

Mg _a R _{11 -ab} T 2 _b (Ni _{1 -xy} Co _x M 4 _y ) _z (7) where R 1 is at least one element selected from rare earth elements containing Y, and T 2 is Ca, Ti and Zr At least one element selected from the group consisting of Mn, Fe, V, C
r, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B are at least one element selected from the group consisting of a,
b, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0
<B ≦ 0.3, 0 <x ≦ 0.5, 0 ≦ y ≦ 0.2, 3 ≦
It is defined as z ≦ 3.8.

As R1 in the formula (7), the same ones as described in the first hydrogen storage alloy can be used.

The reason why the amount (a) of Mg is defined in the above range is as follows. If the amount (a) of Mg is less than 0.2, it may be difficult to enhance the hydrogen release characteristics of the alloy. On the other hand, when the amount (a) of Mg is 0.
If it exceeds 35, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease.

By setting the amount of T2 within the above range,
The characteristics such as the hydrogen release rate can be improved without significantly reducing the hydrogen storage amount, and the hydrogen storage /
Pulverization due to release can be suppressed. Also, T2
When the amount (b) exceeds 0.3, the effect as described above is obtained,
That is, the improvement of the hydrogen release characteristics and the suppression of the pulverization are not observed, and the discharge capacity and the cycle life of the secondary battery including the negative electrode containing the alloy are reduced. A smaller cycle amount (b) tends to obtain a longer cycle life.
From the viewpoint of ensuring a long life, the replacement amount (b) of T2 is preferably set to 0.2 or less.

By setting the amount of Co in the above range,
The reversibility in the storage and release of hydrogen can be improved, and the cycle characteristics of the secondary battery can be significantly improved. In addition, the alloy has a small plateau slope, can reduce hysteresis, and can improve static hydrogen storage characteristics. On the other hand, if the Co amount (x) exceeds 0.5, the hydrogen storage amount may decrease, and when a secondary battery is formed from a negative electrode containing the alloy, an oxidation / reduction reaction of Co occurs. , It may be difficult to obtain a large discharge capacity. A more preferable range of the Co amount (x) is 0.03 ≦ x ≦ 0.35.

By setting the amount of M4 within the above range,
The hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is presumed to be due to the diffusion of hydrogen that has entered the alloy due to the substitution of M4, and the easy absorption and release of hydrogen. Further, a metal oxide-hydrogen secondary battery including a negative electrode containing the alloy,
Cycle characteristics can be dramatically improved.

When the amount (y) of M4 exceeds 0.2, the metal oxide having a negative electrode containing such an alloy is
The discharge capacity of the hydrogen secondary battery may be reduced. The M
A more preferable range of the amount (y) of 0.01 is 0.01 ≦ y ≦ 0.
Fifteen.

The ratio (z) between (Mg + R + T) and (Ni + Co + M) is defined in the above range for the following reason. When the ratio (z) is less than 3.0, hydrogen in the alloy is extremely stabilized, and the amount of hydrogen released from the alloy is reduced. By setting the ratio (z) to 3 or more, it is possible to sufficiently improve the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy, and to improve the discharge capacity and cycle characteristics of the metal oxide. -A hydrogen secondary battery can be realized. However, when the ratio (z) is 3.
If it exceeds 8, the number of hydrogen sites in the alloy may decrease and the hydrogen storage amount may decrease. A more preferable range of the ratio (z) is 3.0 ≦ z ≦ 3.6.

The seventh hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

This seventh hydrogen storage alloy is produced by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(H) Eighth Hydrogen Storage Alloy This alloy is produced by a casting method or a sintering method and has a composition represented by the following general formula (8) or a crushed alloy ingot. Including things.

Mg _a (La _{1 -b} R _{1 b} ) _{1 -a} Ni _z (8) where R 1 is at least one element selected from rare earth elements containing Y, and is not La but a, b And z are 0.2 ≦ a ≦ 0.35 and 0.01 ≦ b <, respectively.
0.5, 3 ≦ z ≦ 3.8.

As the R1 in the above formula (8), the same ones as described in the first hydrogen storage alloy can be used.

The amount (a) of Mg is defined in the above range for the following reason. If the amount (a) of Mg is less than 0.2, it may be difficult to enhance the hydrogen release characteristics of the alloy. On the other hand, when the amount (a) of Mg is 0.
If it exceeds 35, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease.

The value of (b) in the above alloy is defined in the above range for the following reason. The R
If the amount (b) of 1 is less than 0.01, it may be difficult to increase the hydrogen equilibrium pressure of the alloy and the operating voltage of the secondary battery. Although the hydrogen equilibrium pressure of the alloy increases as the value of (b) increases, when the value of (b) is 0.5 or more, the hydrogen storage amount may decrease.

The reason for setting the value of (z) in the above alloy in the above range is as follows. When the value of (z) is less than 3, the stored hydrogen becomes very stable and becomes difficult to release. For this reason, the discharge capacity of the secondary battery including the negative electrode containing the alloy is reduced. On the other hand, when the value of (z) exceeds 3.8, the number of sites into which hydrogen in the hydrogen storage alloy enters may decrease. The more preferable range of the above (z) is 3.0 ≦ z ≦ 3.6.

[0175] The alloy is Vickers.
s) Preferably, the hardness Hv is less than 700 (kgf / mm ² ). When the hardness Hv is 700 or more, the cycle life of a secondary battery provided with a negative electrode containing the alloy may be significantly reduced. This is the Hv of the hydrogen storage alloy.
Is 700 or more, the fracture toughness value K _IC becomes small and becomes brittle, so that it is presumed that cracking of the alloy is accelerated by the absorption and desorption of hydrogen, and the current collection efficiency of the negative electrode is reduced. . A more preferable range of the hardness Hv is 650.
(Kgf / mm ² ). A more preferred range is less than 600 (kgf / mm ² ).

The eighth hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The eighth hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

It is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(I) Ninth Hydrogen Storage Alloy This alloy is manufactured by a casting method or a sintering method and has a composition represented by the following general formula (9) or a crushed alloy ingot. Including things.

Mg _a (La _1−b R1 _b ) _1−a (Ni _1−x M3 _x ) _z (9) where R1 is at least one element selected from rare earth elements including Y, and Not La, M3 is C
o, Mn, Fe, Al, Ga, Zn, Sn, Cu, Si
And at least one element selected from B and a,
b, x and z are 0.2 ≦ a ≦ 0.35 and 0.0, respectively.
1 ≦ b <0.5, 0.1 ≦ x ≦ 0.6, 3 ≦ z ≦ 3.8
Is defined as

Examples of the R1 include the same ones as described in the first hydrogen storage alloy.

The amount (a) of Mg is defined in the above range for the following reason. If the amount (a) of Mg is less than 0.2, it may be difficult to enhance the hydrogen release characteristics of the alloy. On the other hand, when the amount (a) of Mg is 0.
If it exceeds 35, the crystal structure of the alloy changes, and the hydrogen storage amount may decrease.

The value of (b) in the above alloy is defined in the above range for the following reason. The R
If the amount (b) of 1 is less than 0.01, it may be difficult to increase the hydrogen equilibrium pressure of the alloy and the operating voltage of the secondary battery. Although the hydrogen equilibrium pressure of the alloy increases as the value of (b) increases, when the value of (b) is 0.5 or more, the hydrogen storage amount may decrease.

By setting the value of (x) in the above alloy to the above range, absorption and desorption of hydrogen can be easily performed, so that the discharge capacity of a secondary battery provided with a negative electrode containing the above alloy can be improved. can do. In addition, since the alloy has good corrosion resistance, the cycle life can be improved. The more preferable range of the (x) is 0.1 ≦ x ≦
0.5.

The reason why the value of (z) in the above alloy is set in the above range is as follows. When the value of (z) is less than 3, the stored hydrogen becomes very stable and becomes difficult to release. For this reason, the discharge capacity of the secondary battery including the negative electrode containing the alloy is reduced. On the other hand, when the value of (z) exceeds 3.8, the number of sites into which hydrogen in the hydrogen storage alloy enters may decrease. The more preferable range of the above (z) is 3.0 ≦ z ≦ 3.6.

The above-mentioned alloy is formed by Vickers for the same reason as described in the eighth alloy.
s) Preferably, the hardness Hv is less than 700 (kgf / mm ² ). A more preferred range of the hardness Hv is 6
It is less than 50 (kgf / mm ² ). A more preferred range is less than 600 (kgf / mm ² ).

The ninth hydrogen storage alloy includes C,
Elements such as N, O, and F may be included as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

This ninth hydrogen storage alloy is manufactured by the above-described casting method or sintering method.

Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as described for the first hydrogen storage alloy.

(K) Tenth Hydrogen Storage Alloy The tenth hydrogen storage alloy includes an alloy having a composition represented by the following general formula (10).

Mg _a R 2 _1-ab T1 _b (Ni _1-x M3 _x ) _z (10) where R 2 is at least two elements selected from rare earth elements including Y, and the Ce content of R 2 Is 20% by weight
T1 is at least one element selected from Ca, Ti, Zr and Hf, and M3 is Mn, Fe, C
at least one element selected from the group consisting of o, Al, Ga, Zn, Sn, Cu, Si and B, a, b, x and z
Are respectively 0 <a ≦ 0.5, 0 ≦ b ≦ 0.3, 0 ≦ x
≦ 0.9 and 3 ≦ z <4.

The value of (a) in the above alloy is defined in the above range for the following reason. If the value of (a) exceeds 0.5, the crystal structure of the alloy may change, and the amount of hydrogen occlusion may decrease significantly. As a result, the discharge capacity may decrease. The preferred range of (a) is 0.1 ≦ a ≦ 0.4, and the more preferred range is 0.2 ≦ a ≦ 0.35.

When Ce is contained in the alloy, the corrosion resistance of the alloy is improved, but when the content of Ce in R2 is 20% by weight or more, the alloy has a crystal structure different from the intended crystal structure. Due to the presence of many phases, the properties of the alloy at high temperatures may be degraded. In addition, a secondary battery provided with a negative electrode containing the alloy may have deteriorated charge / discharge characteristics in a high-temperature environment. When the Ce content of R2 is smaller, the high-temperature characteristics of the alloy are improved, and the high-temperature charge / discharge characteristics of the secondary battery tend to be improved. A more preferred range for the Ce content of R2 is less than 18% by weight, and a more preferred range is less than 16% by weight.

It is preferable that R2 contains La. When R2 is formed only from La, although the discharge capacity of the secondary battery is improved, the corrosion resistance of the alloy is reduced, and the cycle life of the secondary battery is reduced. The R
Preferably, the La content in 2 is greater than 70% by weight. By setting the La content in the above range in R2 having a Ce content of less than 20% by weight, the discharge capacity can be improved without lowering the corrosion resistance of the hydrogen storage alloy.

R2 is preferably made of La, Ce, Pr and Nd from the viewpoint of reducing the cost of the hydrogen storage alloy and the hydrogen storage electrode.

T1 has the function of suppressing the progress of pulverization of the hydrogen storage alloy without significantly reducing the discharge capacity of the secondary battery. It is more preferable to use Ca and Zr as T1. The reason why the substitution amount (b) at T1 is set in the above range is as follows. When the replacement amount (b) exceeds 0.3, the discharge capacity of the secondary battery decreases, and the effect of suppressing pulverization decreases. A more preferable range of the substitution amount (b) is 0 ≦ b ≦ 0.2, and a more preferable range is 0 ≦ b ≦ 0.1.

M3 is Mn, Fe, Co, Al, Ga, Z
at least one selected from n, Sn, Cu, Si and B
Among these elements, it is preferable to use Mn, Co, and Al. By defining the substitution amount (x) in M3 within the above range, the hydrogen storage / release rate of the hydrogen storage alloy can be improved, and the discharge and storage of hydrogen can be performed easily. Capacity can be improved,
Furthermore, the cycle resistance can be improved because the corrosion resistance of the hydrogen storage alloy is improved. A more preferable range of the substitution amount (x) is 0.01 ≦ x ≦ 0.6, and a further preferable range is 0.01 ≦ x ≦ 0.5.

The reason for defining the value of (z) in the above alloy in the above range is as follows. If the value of (z) is less than 3, the stored hydrogen becomes very stable, so that it becomes difficult to release the hydrogen. As a result, the discharge capacity may decrease. On the other hand, when (z) is set to 4 or more, the number of sites into which hydrogen in the hydrogen storage alloy enters is reduced, and as a result, the discharge capacity may be reduced. The more preferable range of the above (z) is 3.0 ≦ z ≦ 3.8. A more preferred range is 3.0 ≦ z ≦ 3.6.

The tenth hydrogen storage alloy includes:
Elements such as C, N, O, and F may be contained as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The tenth hydrogen storage alloy is produced, for example, by a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy. According to the tenth hydrogen storage alloy, a secondary battery having excellent charge / discharge characteristics can be obtained even when the secondary battery is manufactured by the molten metal quenching method or the ultra-quenching method. It is presumed that this is because the tenth hydrogen storage alloy produced by the method has few surface defects.

(L) Eleventh Hydrogen Storage Alloy This eleventh hydrogen storage alloy includes an alloy having a composition represented by the following general formula (11).

Mg _a R 3 _1-ab T1 _b (Ni _1-xy M5 _x Co _y ) _z (11) where R3 is two or more elements selected from rare earth elements including Y, and T1 is Ca, M5 is at least one element selected from Ti, Zr and Hf, and M5 is Mn,
At least one element selected from the group consisting of Fe, Al, Ga, Zn, Sn, Cu, Si and B, a, b, x, y
And z are respectively 0 <a ≦ 0.5, 0 ≦ b ≦ 0.3,
0 ≦ x ≦ 0.9, 0 <y ≦ 0.4, x + y ≦ 0.9, 3
≦ z <4, the Ce content of R3 is less than m% by weight, and m is represented by the following formula (I).

M = 125y + 20 (I) where y in the above equation (I) is Co in the above equation (11).
Indicates the amount.

The value of (a) in the above alloy is defined in the above range for the following reason. If the value of (a) exceeds 0.5, the crystal structure of the alloy may change, and the amount of hydrogen occlusion may decrease significantly. As a result, the discharge capacity may decrease. The preferred range of (a) is 0.1 ≦ a ≦ 0.4, and the more preferred range is 0.2 ≦ a ≦ 0.35.

The content of Ce in R3 is defined by the above formula (I) for the following reasons. The formula (I) is derived by the inventors through repeated experiments. That is, the present inventors have conducted extensive experiments, and as a result,
It has been found that there is a correlation between the Co content and the Ce content of the hydrogen storage alloy. When the hydrogen storage alloy (particularly, a hydrogen storage alloy containing La) contains Ce, the corrosion resistance of the alloy is improved. However, when the Ce content increases, the number of phases having a crystal structure different from the intended crystal structure increases. By adding Co to this alloy, generation of a phase having a crystal structure different from the intended purpose can be suppressed. That is, by changing the content of Ce in R3 according to the amount of Co in the hydrogen storage alloy, the corrosion resistance can be increased while maintaining a preferable crystal structure. Specifically, as shown in FIG. 1, when the Ce content in R3 is set to a value calculated from the formula (I); m = 125y + 20 or more, the crystal structure of the hydrogen storage alloy is changed. Since this is significantly different from the intended one, the high-temperature characteristics of the alloy and the high-temperature charge / discharge characteristics of the secondary battery may be reduced. By making the Ce content in R3 smaller than the value obtained from the above-mentioned formula (I) as in the present invention, the hydrogen storage alloy can maintain a preferable crystal structure, and particularly, the high-temperature properties of the alloy can be improved. The charge / discharge characteristics of the secondary battery at high temperatures can be improved.

It is preferable that R3 contains La. From the viewpoint of reducing the cost of the hydrogen storage alloy and the hydrogen storage electrode, it is preferable that R3 be made of La, Ce, Pr and Nd.

[0207] T1 has a function of suppressing the progress of pulverization of the hydrogen storage alloy without significantly reducing the discharge capacity of the secondary battery. It is more preferable to use Ca and Zr as T1. The reason why the substitution amount (b) at T1 is set in the above range is as follows. When the replacement amount (b) exceeds 0.3, the discharge capacity of the secondary battery decreases, and the effect of suppressing pulverization decreases. A more preferable range of the substitution amount (b) is 0 ≦ b ≦ 0.2, and a more preferable range is 0 ≦ b ≦ 0.1.

M5 is Mn, Fe, Co, Al, Ga, Z
at least one selected from n, Sn, Cu, Si and B
Among these elements, it is preferable to use Mn, Co, and Al. By defining the substitution amount (x) in M3 within the above range, the hydrogen storage / release rate of the hydrogen storage alloy can be improved, and the discharge and storage of hydrogen can be performed easily. The capacity can be improved, and the cycle characteristics can be improved because the corrosion resistance of the hydrogen storage alloy is improved. A more preferable range of the substitution amount (x) is 0.01 ≦ x ≦ 0.6, and a further preferable range is 0.01 ≦ x ≦ 0.5.

The value of the amount of Co (y) in the alloy is defined in the above range for the following reason.
If the value of the Co amount (y) exceeds 0.4, the hydrogen storage amount of the alloy may decrease, and a high-capacity secondary battery may not be obtained. This is considered to be due to the fact that as the amount of Co (y) increases, the allowable value of the amount of Ce in R3 calculated by the formula (I) increases. A more preferable range of the Co amount (y) is 0 <y <0.35.

By defining the value of (x + y) in the above alloy in the above range, the cycle characteristics can be improved. The more preferable range of the (x + y) is 0
<X + y ≦ 0.6.

[0211] The value of (z) in the above alloy is defined in the above range for the following reason. If the value of (z) is less than 3, the stored hydrogen becomes very stable, so that it becomes difficult to release the hydrogen. As a result, the discharge capacity may decrease. On the other hand, when (z) is set to 4 or more, the number of sites into which hydrogen in the hydrogen storage alloy enters is reduced, and as a result, the discharge capacity may be reduced. The more preferable range of the above (z) is 3.0 ≦ z ≦ 3.8. A more preferred range is 3.0 ≦ z ≦ 3.6.

Further, the eleventh hydrogen storage alloy includes:
Elements such as C, N, O, and F may be contained as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The eleventh hydrogen storage alloy is produced, for example, by a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy. According to the eleventh hydrogen storage alloy, a secondary battery having excellent charge / discharge characteristics can be obtained even when manufactured by the molten metal quenching method or the ultra quenching method, because the molten metal quenching method or the ultra This is presumed to be because the eleventh hydrogen storage alloy produced by the method has few surface defects.

(L) Twelfth Hydrogen Storage Alloy This twelfth hydrogen storage alloy has a composition represented by the following general formula (12), and a and z in the general formula (12) satisfy the following (II) )) Includes an alloy in which the crystal phase satisfying the formula is the main phase, and the number of plane defects in the main phase is 20 or less per 100 nm.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (12) where R 1 is at least one element selected from rare earth elements containing Y, and T 1 is Ca, Ti, Zr, At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

Z = −6 × a + δ (II) Here, δ may be within the range of 4.8 ≦ δ ≦ 5.2, but is most preferably 5.0.

Here, the main phase means the phase having the highest abundance ratio among the phases present in the alloy.

The composition analysis of each crystal phase of the alloy is performed by using an EDX analyzer of a transmission electron microscope with a beam diameter of 4 nm. Further, the plane defect in the crystal phase of the alloy means a linear defect that can be observed by taking a transmission electron microscope image of a crystal grain constituting the crystal phase. The measurement of the plane defect in the crystal phase of the alloy can be performed by the method (a) or (b) described below. That is,
(A) Using a transmission electron microscope, a transmission electron microscope image is taken at a magnification of 10,000 to 100,000, and the number of surface defects per unit length is measured. (B) (1, 0, 0) of the crystal grains of the alloy
By observing the plane, the number of plane defects existing perpendicular to the C axis of the crystal grain is measured.

An alloy containing, as a main phase, a crystal phase having a composition in which a and z in the general formula (12) do not satisfy the aforementioned formula (II) is inferior in hydrogen storage / release characteristics. The number of plane defects in the main phase of the hydrogen storage alloy is defined in the above range for the following reason. If the number of plane defects in the main phase exceeds 20 per 100 nm, it becomes difficult to improve the hydrogen release characteristics and cycle characteristics of the alloy. Therefore, it becomes difficult to realize a secondary battery having a large discharge capacity and excellent cycle life. Further, by reducing the number of plane defects in the main phase to 10 or less per 100 nm, the hydrogen storage / release characteristics of the alloy can be further improved, and particularly, the cycle characteristics can be significantly improved, and the discharge characteristics can be improved. A metal oxide / hydrogen secondary battery with improved capacity and cycle life can be realized.

As the R1, the same one as described in the first hydrogen storage alloy can be used.

By substituting a part of the R1 for the T1, the characteristics such as the hydrogen release rate can be improved without significantly reducing the hydrogen storage capacity of the alloy, and the fine powder accompanying the hydrogen storage and release can be improved. Can be suppressed. When the amount (b) of T1 exceeds 0.3, the above-mentioned effects, that is, the improvement of the hydrogen release characteristics and the suppression of pulverization cannot be seen, and the secondary battery including the negative electrode containing the alloy cannot be used. The discharge capacity decreases. The cycle life tends to be longer when the amount (b) of T1 is smaller. Therefore, from the viewpoint of securing a long life, the amount of the T1 (b)
Is preferably 0.2 or less.

By substituting a part of Ni with M6, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is because part of Ni is M6
This is presumed to be caused by, for example, the diffusion of hydrogen invading into the alloy and the facilitated absorption and release of hydrogen by the alloy. Further, the metal oxide / hydrogen secondary battery including the negative electrode containing the alloy can improve the cycle life. However, if the amount (x) of the M6 exceeds 0.6, the discharge capacity may decrease. Therefore, the amount (x) of the M6 is set to 0 ≦ x ≦ 0.6. A more preferred range of the amount (x) of the M6 is 0.0
1 ≦ x ≦ 0.5.

The reason why the amount (a) and the ratio (z) of Mg in the general formula (12) are defined in the above ranges is as follows. Mg amount (a) is 0.2 ≦ a
When the ratio (z) deviates from ≦ 0.35 and the ratio (z) deviates from 3 ≦ z ≦ 3.8, the number of plane defects in the main phase of the alloy is 2 per 100 nm.
There is a risk of exceeding zero. A more preferable range of the ratio (z) is 3 ≦ z ≦ 3.6.

The twelfth hydrogen storage alloy according to the present invention includes:
Elements such as C, N, O, and F may be contained as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The twelfth hydrogen storage alloy is produced by, for example, a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy.

In the case where the hydrogen storage alloy according to the present invention is produced by the above-mentioned molten metal quenching method or ultra-quenching method,
1 preferably contains less than 20% by weight of Ce. If the Ce content of R1 is more than 20% by weight, the number of plane defects in the main phase may be more than 20 per 100 nm. Further, the alloy composition that can be produced by the quenching method, that is, the allowable value of the Ce content in R1 changes depending on the type and amount of the substitution element in the Ni site. For example, the substitution element for Ni site is C
o, the amount of C in R1 increases with an increase in the amount of Co.
The tolerable limit of e content tends to increase. In particular,
When the Co amount (x) is 0.2, the Ce content in R1 is 4
Up to about 5% by weight can be tolerated.

(M) Thirteenth Hydrogen Storage Alloy The thirteenth hydrogen storage alloy has a composition represented by the following general formula (13), and a and z in the above general formula (13) satisfy the following (II) )) The alloy contains an alloy containing more than 70% by volume of a crystal phase satisfying the formula as a main phase, and having a crystal defect having 20 or less plane defects per 100 nm in crystal grains.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (13) where R 1 is at least one element selected from rare earth elements containing Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

Z = −6 × a + δ (II) Here, δ may be within the range of 4.8 ≦ δ ≦ 5.2, but is most preferably 5.0.

Here, the main phase means a phase having the highest abundance ratio among the phases existing in the alloy.

The composition analysis of the crystal phase of the alloy and the plane defects in the crystal grains can be measured by the same method as described in the thirteenth hydrogen storage alloy.

An alloy containing, as a main phase, a crystal phase having a composition in which a and z in the general formula (13) do not satisfy the above-mentioned formula (II) is inferior in hydrogen storage / release characteristics. Further, in the hydrogen storage alloy, the volume ratio of the crystal phase in which the number of plane defects in crystal grains is 20 or less per 100 nm is defined in the above range for the following reason. If the proportion of the crystal phase in the hydrogen storage alloy is 70% by volume or less, it becomes difficult to improve the hydrogen release characteristics and cycle characteristics of the alloy. Therefore, it becomes difficult to realize a secondary battery having a large discharge capacity and excellent cycle life. Further, the surface defect in the crystal grain is 100 n.
By containing more than 70% by volume of a crystal phase of 10 or less per m, the hydrogen absorption / desorption characteristics of the alloy can be further improved, and in particular, the cycle characteristics can be remarkably improved. A metal oxide / hydrogen secondary battery with improved capacity and cycle life can be realized.

The R1 may be the same as that described in the first hydrogen storage alloy. When R1 contains La, La in R
The amount is preferably at least 50% by weight.

By substituting a part of the R1 with the T1, it is possible to improve the hydrogen release rate and other characteristics without significantly reducing the hydrogen storage capacity of the alloy, and to improve the fine powder accompanying the hydrogen storage and release. Can be suppressed. When the amount (b) of T1 exceeds 0.3, the above-mentioned effects, that is, the improvement of the hydrogen release characteristics and the suppression of pulverization cannot be seen, and the secondary battery including the negative electrode containing the alloy cannot be used. The discharge capacity decreases. The cycle life tends to be longer when the amount (b) of T1 is smaller. Therefore, from the viewpoint of securing a long life, the amount of the T1 (b)
Is preferably 0.2 or less.

By substituting a part of Ni with M6, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is because part of Ni is M6
This is presumed to be caused by, for example, the diffusion of hydrogen invading into the alloy and the facilitated absorption and release of hydrogen by the alloy. Further, the metal oxide / hydrogen secondary battery including the negative electrode containing the alloy can improve the cycle life. However, if the amount (x) of the M6 exceeds 0.6, the discharge capacity may decrease. Therefore, the amount (x) of the M6 is set to 0 ≦ x ≦ 0.6. A more preferred range of the amount (x) of the M6 is 0.0
1 ≦ x ≦ 0.5.

The reason why the amount (a) and the ratio (z) of Mg in the general formula (13) are defined in the above ranges is as follows. Mg amount (a) is 0.2 ≦ a
If the ratio (z) deviates from ≦ 0.35 and the ratio (z) deviates from 3 ≦ z ≦ 3.8, the abundance of crystal grains having more than 20 plane defects per 100 nm may be 30% by volume or more. A more preferable range of the ratio (z) is 3 ≦ z ≦ 3.6.

The thirteenth hydrogen storage alloy according to the present invention includes:
Elements such as C, N, O, and F may be contained as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The thirteenth hydrogen storage alloy is manufactured by, for example, a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy.

In the case where the hydrogen storage alloy according to the present invention is manufactured by the above-mentioned molten metal quenching method or ultra-quenching method,
1 preferably contains less than 20% by weight of Ce. If the Ce content of R1 is 20% by weight or more, the abundance of crystal grains having a number of plane defects of 20 or less per 100 nm may be 70% by volume or less. Further, the alloy composition that can be produced by the quenching method, that is, the allowable value of the Ce content in R1 changes depending on the type and amount of the substitution element in the Ni site. For example, Ni
When Co is included in the substitution element for the site, the allowable limit of the Ce content in R1 tends to increase as the Co amount increases. Specifically, when the Co amount (x) is 0.2,
The Ce content in R1 can be allowed up to about 45% by weight.

(N) Fourteenth Hydrogen Storage Alloy The fourteenth hydrogen storage alloy has a composition represented by the following general formula (14), and a and z in the above general formula (14) satisfy the following (II) The crystalline phase satisfying the formula is the main phase, and Ca
When the crystal phase having a Cu ₅ type crystal structure is 20% by volume or less,
The alloy includes an alloy in which the crystal phase having the MgCu ₂ type crystal structure is 10% by volume or less.

Mg _a R _{11 -ab} T 1 _b (Ni _{1 -x} M 6 _x ) _z (14) where R 1 is at least one element selected from rare earth elements containing Y, and T 1 is Ca, Ti, Zr and At least one element selected from Hf, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8.

Z = −6 × a + δ (II) Here, δ may be within the range of 4.8 ≦ δ ≦ 5.2, but is most preferably 5.0.

Here, the main phase means a phase having the highest abundance ratio among the phases existing in the alloy.

The abundance of the main phase, the crystal phase having the CaCu ₅ type crystal structure, and the crystal phase having the MgCu ₂ type crystal structure in the hydrogen storage alloy can be identified by, for example, using a scanning electron microscope (SEM). This is performed by taking a secondary electron image and a reflected electron image, and analyzing the composition of each phase using an EDX analyzer of a scanning electron microscope. Further, by performing X-ray diffraction, the crystal form of each phase can be made more certain.

The abundance of each crystal phase in the hydrogen storage alloy is defined in the above range for the following reason. An alloy containing, as a main phase, a crystal phase having a composition in which a and z in the general formula (14) do not satisfy the above-mentioned formula (II) is inferior in hydrogen storage / release characteristics. Although a and z in the general formula (14) contain a crystal phase having a composition satisfying the above-mentioned formula (II), the crystal phase having a CaCu ₅ type crystal structure is 20% by volume.
If the alloy exceeds a certain amount, the hydrogen storage capacity of the alloy decreases. on the other hand,
A and z in the general formula (14) are as described in the above (II)
Although containing a crystal phase having a composition satisfying the formula, Mg
Alloys with a crystal phase having a Cu ₂ type crystal structure exceeding 10% by volume have reduced hydrogen release characteristics. CaC in the alloy
crystalline phase having a u ₅ type crystal structure is preferably set to 10% by volume or less. Further, it is preferable that the crystal phase having the MgCu ₂ type crystal structure in the alloy is 5% by volume or less.

The R1 may be the same as described for the first hydrogen storage alloy. Further, when R1 contains La, L in R1
The amount of a is preferably set to 50% by weight or more.

By substituting a part of the R1 for the T1, the characteristics such as the hydrogen release rate can be improved without significantly reducing the hydrogen storage capacity of the alloy, and the fine powder accompanying the hydrogen storage and release can be improved. Can be suppressed. When the amount (b) of T1 exceeds 0.3, the above-mentioned effects, that is, the improvement of the hydrogen release characteristics and the suppression of pulverization cannot be seen, and the secondary battery including the negative electrode containing the alloy cannot be used. The discharge capacity decreases. The cycle life tends to be longer when the amount (b) of T1 is smaller. Therefore, from the viewpoint of securing a long life, the amount of the T1 (b)
Is preferably 0.2 or less.

By substituting a part of Ni with M6, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the alloy can be improved. This is because part of Ni is M6
This is presumed to be caused by, for example, the diffusion of hydrogen invading into the alloy and the facilitated absorption and release of hydrogen by the alloy. Further, the metal oxide / hydrogen secondary battery including the negative electrode containing the alloy can improve the cycle life. However, if the amount (x) of the M6 exceeds 0.6, the discharge capacity may be reduced. Therefore, the amount (x) of the M6 is set to 0 ≦ x ≦ 0.6. A more preferred range of the amount (x) of the M6 is 0.0
1 ≦ x ≦ 0.5.

A fourteenth hydrogen storage alloy according to the present invention includes:
Elements such as C, N, O, and F may be contained as impurities as long as the properties of the alloy are not impaired. The content of these impurities is preferably in the range of 1 wt% or less.

The fourteenth hydrogen storage alloy is produced by, for example, a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy.

In the case where the hydrogen storage alloy according to the present invention is produced by the above-mentioned molten metal quenching method or ultra-quenching method,
1 preferably contains less than 20% by weight of Ce. When the Ce content of R1 is 20% by weight or more, the crystal phase having a CaCu ₅ type crystal structure in the alloy becomes 2%.
This is because there is a possibility that the content will be more than 0% by volume or the crystal phase having the MgCu ₂ type crystal structure will be more than 10% by volume. The alloy composition that can be produced by the quenching method, that is, the allowable value of the Ce content in R1 is Ni.
It varies depending on the type and amount of the substitution element on the site.
For example, when Co is contained in the substitution element for the Ni site, the allowable limit of the Ce content in R1 tends to increase as the Co content increases. Specifically, when the Co amount (x) is 0.2, the Ce content in R1 can be allowed up to about 45% by weight.

(O) Fifteenth Hydrogen Storage Alloy This fifteenth hydrogen storage alloy is represented by the following general formula (15) and has a main phase of Ce ₂ Ni ₇ type, CeNi ₃ type, Gd
_At least one selected from phases having a crystal structure of either ₂ Co ₇ type or PuNi ₃ type or a similar crystal structure
Includes an alloy that is one phase.

R1 _1-ab Mg _a T2 _b (Ni _1-x M7 _x ) _z (15) where R1 is at least one element selected from rare earth elements containing yttrium, and T2 is Ca, Ti, Zr At least one selected element, M7 is Co, Mn,
Fe, V, Cr, Nb, Al, Ga, Zn, Sn, C
at least one element selected from u, Si, P, and B, and a, b, x, and z are each 0 <a ≦ 0.6, 0 ≦
It is defined as b ≦ 0.5, 0 ≦ x ≦ 0.9, 2.5 ≦ z <4.5.

Here, the “main phase” refers to the Ce ₂ Ni
Whether at least one phase selected from a phase having any one of a crystal structure of type ₇ , CeNi ₃ type, Gd ₂ Co ₇ type, and PuNi ₃ type or a phase having a similar crystal structure occupies the largest volume in the hydrogen storage alloy; , Which means that it occupies the largest area in the cross section of the hydrogen storage alloy. In particular, it is preferable that at least one phase selected from the above-described phases having a crystal structure exists in an area ratio of 50% or more with respect to the hydrogen storage alloy. If the proportion of this phase is less than 50%, the hydrogen storage capacity may decrease. For this reason, a secondary battery provided with a negative electrode containing this hydrogen storage alloy may have a reduced discharge capacity or a reduced charge / discharge cycle life. A more preferred area ratio of the phase is 60% or more.

The crystal structure of any of Ce ₂ Ni ₇ type and CeNi ₃ type or a similar crystal structure belongs to hexagonal crystal. On the other hand, any crystal structure of the Gd ₂ Co ₇ type or PuNi ₃ type or a similar crystal structure belongs to the rhombohedron.
In addition, each said similar crystal structure means the crystal structure which can be represented by the plane index of each said crystal type in an X-ray diffraction pattern. A more preferred crystal type is PuNi.
Type ₃ and Ce ₂ Ni ₇ types also include crystal structures that can be represented by plane indices of these crystal types.

The hydrogen storage alloy is allowed to include a phase having an AB ₅ type crystal structure such as CaCu ₅ type and a phase having an AB ₂ type crystal structure such as MgCu ₂ .

Next, the reason for defining the functions and component amounts of the respective elements R1, Mg, T2, and M7 will be described.

1-1) R1 R1 is a rare earth element containing yttrium, but it is preferable to use a misch metal from the viewpoint of reducing the production cost. Misch metal is a mixture of rare earth elements, and the content of La, Ce, Pr and Nd is 99% by weight.
Means the above alloys. As this misch metal,
Mm in which Ce is 50% by weight or more and La content is 30% by weight or less, and lanthanum-rich misch metal (Lm) in which La content is larger than Mm.

1-2) Mg By setting the amount of Mg within the above range, it is possible to obtain a hydrogen storage alloy having a large amount of hydrogen storage and improved hydrogen release properties. For this reason, the secondary battery provided with the negative electrode containing this hydrogen storage alloy has an improved discharge capacity.

When the substitution amount (a) of Mg with respect to R1 is 0.6
If it exceeds, the hydrogen storage amount of the hydrogen storage alloy is significantly reduced. The preferred substitution amount (a) is 0.5 or less, more preferably 0.15 ≦ a ≦ 0.4, and still more preferably 0.5.
2 ≦ a ≦ 0.35.

1-3) T2 The substitution element T2 for R1 is at least one element selected from Ca, Ti, and Zr.
By the substitution of 1, without reducing the hydrogen storage amount of the hydrogen storage alloy, it is possible to improve the characteristics such as the hydrogen release rate,
It is possible to suppress the pulverization of the alloy due to hydrogen storage and release.

If the substitution amount (b) of T2 with respect to R1 exceeds 0.5, the above-mentioned effects, that is, the improvement of the hydrogen release characteristics and the suppression of pulverization may not be sufficiently exhibited. For this reason, a secondary battery provided with a negative electrode containing a hydrogen storage alloy having a substitution amount (b) of T2 exceeding 0.5 may have a reduced discharge capacity. The preferred substitution amount (b) is 0.4 or less, more preferably 0.3 or less, and even more preferably 0.1 or less.

1-4) M7 The substitution element M7 for Ni is Co, Mn, Fe, V, Cr,
At least one element selected from Nb, Al, Ga, Zn, Sn, Cu, Si, P, and B. By this substitution, the hydrogen storage / release characteristics such as the hydrogen storage / release speed of the hydrogen storage alloy are obtained. Can be improved. This is presumably due to the fact that the substitution of M7 facilitates the diffusion of hydrogen that has entered the hydrogen storage alloy. A metal oxide / hydrogen secondary battery including a negative electrode containing such a hydrogen storage alloy can dramatically improve cycle characteristics.

When the substitution amount (x) of M7 with Ni exceeds 0.9, the hydrogen storage / release characteristics may be deteriorated. The more preferable substitution amount (x) is 0.6 or less, and further preferably 0.01 ≦ x ≦ 0.5.

The value of z in the above general formula is defined as 2.5 ≦ z <4.5.
, Ce ₂ Ni ₇ type, CeNi ₃
, Gd ₂ Co ₇ type, PuNi ₃ type or at least one phase selected from phases having a similar crystal structure becomes a main phase, and the hydrogen storage alloy has
Hydrogen storage / release characteristics such as release rate can be significantly improved. Therefore, the secondary battery including the negative electrode including the hydrogen storage alloy has a high discharge capacity and improved cycle characteristics.

When z is less than 2.5, a phase having an AB ₂ -type crystal structure such as MgCu ₂ type other than the above-described phase having a crystal structure becomes a main phase, and the hydrogen storage alloy has a hydrogen storage property. -It becomes difficult to improve the hydrogen storage / release characteristics such as the release rate. Meanwhile, the z and becomes the phase main phase having AB ₅ type crystal structure such as CaCu ₅ type other than the phase with the crystal structure described above and to 4.5 or more, the hydrogen storage alloy hydrogen storage and release It becomes difficult to improve hydrogen storage / release characteristics such as speed. More preferably the z
Is 3 ≦ z ≦ 4.

The hydrogen-absorbing alloy is allowed to contain impurities such as C, N, O, and F within a range that does not impair its characteristics. Note that each of these impurities is preferably in a range of 1% by weight or less.

The fifteenth hydrogen storage alloy is produced by, for example, a casting method, a sintering method, for example, a melt quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method. Further, it is preferable that the alloy thus obtained is subjected to the same heat treatment as that described for the first hydrogen storage alloy.

In the case where the hydrogen storage alloy according to the present invention is produced by the above-mentioned molten metal quenching method or ultra-quenching method,
1 preferably contains less than 20% by weight of Ce. When the Ce content of R1 is 20% by weight or more,
Ce ₂ Ni ₇ type, CeNi ₃ type, Gd ₂ Co ₇ type, Pu
A phase other than a phase having any crystal structure of the Ni ₃ type or a similar crystal structure (for example, A phase such as MgCu ₂ type)
This is because a phase having a B ₂ type crystal structure or a phase having an AB ₅ type crystal structure such as CaCu ₅ type may be a main phase. Further, the alloy composition that can be produced by the quenching method, that is, the allowable value of the Ce content in R1 changes depending on the type and amount of the substitution element in the Ni site. For example, when Co is contained in the substitution element for the Ni site, the allowable limit of the Ce content in R1 tends to increase as the Co content increases. Specifically, when the amount of Co (x) is 0.
In the case of 2, the Ce content in R1 can be allowed up to about 45% by weight.

(P) Sixteenth Hydrogen Storage Alloy This sixteenth hydrogen storage alloy is represented by the following general formula (16), and has a range of 2θ = 8 to 13 ° in an X-ray diffraction pattern using CuKα ray. And an intensity ratio (I ₁ / I ₂ ) of the intensity of the strongest peak (I ₁ ) appearing in the above to the intensity of the strongest peak (I ₂ ) of all peaks is less than 0.15.

R4 _1-ab Mg _a M8 _b (Ni _1-x M9 _x ) _z (16) where R4 is a rare earth element containing yttrium and C
at least one element selected from a, M8 is an element having a higher electronegativity than Mg (except for R4, Ni and M9), and M9 is Co, Mn, Fe, V, Cr, Nb, A
1, at least one element selected from Ga, Zn, Sn, Cu, Si, P, and B, where a, b, x, and z are respectively 0 <a ≦ 0.6, 0 ≦ b ≦ 0.5, 0 ≦ x ≦ 0.
9, 2.5 ≦ z <4.5.

The reasons for defining the functions and amounts of the elements R4, M8 and M9 will be described below.

1) R4 When a rare earth element containing yttrium is used as R4, it is preferable to use a misch metal from the viewpoint of reducing the production cost. Misch metal is a mixture of rare earth elements and means an alloy having a content of La, Ce, Pr and Nd of 99% by weight or more. As this misch metal, Ce is 50% by weight or more and La content is 30%.
A lanthanum-rich misch metal (Lm) having a content of Mm or La which is less than or equal to% by weight, which is higher than that of Mm.

2) Mg By setting a in the above formula (16) to the above range, it is possible to obtain a hydrogen storage alloy having a large amount of hydrogen storage and improved hydrogen release properties. For this reason, the secondary battery provided with the negative electrode containing this hydrogen storage alloy has an improved discharge capacity.

When the value of a exceeds 0.6, the hydrogen storage amount of the hydrogen storage alloy is significantly reduced. A more preferable value of a is
0.5 or less, more preferably 0.15 ≦ a ≦ 0.4, and still more preferably 0.2 ≦ a ≦ 0.35.

3) M8 M8 is an element having a higher electronegativity than Mg (however, R
4, excluding Ni and M9). Specifically, Al:
1.5, Ta: 1.5, V: 1.6, Nb: 1.6, G
a: 1.6, In: 1.7, Ge: 1.8, Pb: 1.
8, Mo: 1.8, Sn: 1.8, Si: 1.8, R
e: 1.9, Ag: 1.9, B: 2.0, C: 2.5,
P: 2.1, Ir: 2.2, Rh: 2.2, Ru: 2.
2, Os: 2.2, Pt: 2.2, Au: 2.4, S
e: 2.4, S: 2.5. M1
Can be at least one selected from these elements. In addition, in each element, the numerical value after: indicates the electronegativity of the metal when the value of Pauling is used. Here, Mg has an electronegativity of 1.2 when a polling value is used.

By substituting said Mg for M8,
The hydrogen equilibrium pressure of the alloy can be increased.

The M8-substituted alloy makes it possible to improve the speed of storing and releasing hydrogen. This is presumed to be due to the following mechanism.

That is, in general, in many hydrides of simple metals, the larger the difference in electronegativity between metal and hydrogen, the larger the bonding force. Considering how the bonding force between metal and hydrogen changes by replacing the Mg component with a different element from the viewpoint of electronegativity, the larger the difference in electronegativity with hydrogen is, the greater the difference between metal and hydrogen is. The ionic bond during bonding between them becomes stronger, and the bonding force becomes stronger, so that the stored hydrogen becomes more stable. Therefore, by substituting Mg with M8 having a higher electronegativity than Mg, it is possible to destabilize hydrogen in the crystal lattice of the alloy. As a result, the hydrogen storage / release characteristics of the hydrogen storage alloy are improved.

In particular, by using Al, Ag and both of them as M8, the crystal lattice of the hydrogen storage alloy can be expanded, so that the hydrogen storage / release characteristics can be further improved.

When b in the above equation (16) exceeds 0.5,
The crystal structure of the hydrogen-absorbing alloy may change significantly, and the original properties of the Mg-based alloy may be impaired. In addition, the hydrogen storage alloy may significantly reduce the catalytic activity during storage. A preferred value of b is 0.4 or less, more preferably 0.3 or less, and still more preferably 0.1 or less.

4) M9 M9 does not exothermically react with hydrogen which facilitates the release of stored hydrogen, that is, Co, M, which is unlikely to spontaneously produce hydrides.
n, Fe, V, Cr, Nb, Al, Ga, Zn, Sn,
At least one element selected from Cu, Si, P, and B is used. In particular, Co and Mn are preferable as M9. An alkaline secondary battery provided with such a negative electrode containing a hydrogen storage alloy in which Ni has been substituted by M9 has improved cycle characteristics, and particularly when Co is used, has improved discharge capacity.

If x in the above formula (16) exceeds 0.9, the crystal structure of the hydrogen storage alloy changes significantly, and the inherent properties of the Mg-based alloy may be impaired. The more preferable substitution amount x is 0.6 or less, further preferably 0.01 ≦
x ≦ 0.5.

[0284] If the content z of Ni and M9 in the alloy is less than 2.5, a large amount of hydrogen is accumulated in the alloy, so that the hydrogen release rate may decrease. On the other hand, when the content z is set to 4.5 or more, there is a possibility that an AB ₅ phase is generated and the discharge capacity of a secondary battery including a negative electrode containing this alloy is reduced. More preferable content z is 3.0 ≦ z
≦ 4.0.

When a in the general formula (16) of the hydrogen storage alloy exceeds 0.6, the X-ray diffraction pattern shows 2θ.
= 8 to 13 ° increases. When the strongest peak intensity increases, the hydrogen storage characteristics decrease. Therefore, the intensity ratio (I ₁ / I ₂ ) between the intensity of the strongest peak (I ₁ ) and the intensity of the strongest peak of all peaks (I ₂ ) must be less than 0.15. When the strength ratio (I ₁ / I ₂ ) of the hydrogen storage alloy is larger than 0.15 only by casting, the strength ratio can be reduced by performing an appropriate heat treatment, and the storage characteristics can be reduced. Can be improved.

The sixteenth hydrogen storage alloy is manufactured by, for example, a casting method, a sintering method, for example, a molten metal quenching method such as a single roll method or a twin roll method, or an ultra quenching method such as a gas atomizing method.

The alloy obtained by such a method may be subjected to a heat treatment in a vacuum or an inert atmosphere at a temperature of 300 ° C. or more and less than the melting point for 0.1 to 500 hours. As a preferable heat treatment method, 0.5 to 1000 ° C.
After performing the heat treatment for 20 hours, a two-stage heat treatment in which the heat treatment is performed at a temperature lower than the heat treatment temperature, for example, 500 to 800 ° C. for 25 to 800 hours.

In the case where the hydrogen storage alloy according to the present invention is produced by the above-mentioned molten metal quenching method or ultra-quenching method,
4 preferably contains less than 20% by weight of Ce. When the Ce content of R4 is 20% by weight or more,
This is because the above-mentioned intensity ratio (I ₁ / I ₂ ) may be 0.15 or more. Further, the alloy composition that can be produced by the quenching method, that is, the allowable value of the Ce content in R4 varies depending on the type and the amount of the substitution element in the Ni site. For example, when Co is contained in the substitution element for the Ni site, the allowable limit of the Ce content in R4 tends to increase as the Co content increases. Specifically, the amount of Co (x)
Is 0.2, the Ce content in R4 can be allowed up to about 45% by weight.

(Q) Seventeenth Hydrogen Storage Alloy This seventeenth hydrogen storage alloy is composed of an A ₂ B ₄ subcell and an AB ₅
It includes a crystal phase composed of a unit cell in which sub-cells are stacked. In the unit cell, a ratio X of the number of A ₂ B ₄ subcells to the number of AB ₅ subcells is 0.5 <X <1.
It is.

The element A has a heat of formation of hydride ΔH (kJ / mol) of 20 k per mole of hydrogen at 25 ° C.
One or more elements smaller than J / mol. As the element A, various elements can be used for various purposes. In order to increase the hydrogen storage amount of the hydrogen storage alloy, it is preferable to use, as the element A, an element which easily generates a hydride spontaneously. Specifically, rare earth elements including Y, Ca, Sr, Mg, Sc, Ti, Zr, V, N
At least one element selected from b, Hf and Ta can be mentioned. Among them, those containing Mg and the rare earth element are preferable. In particular, the element A preferably contains 1 mol% or more and less than 20 mol% of Mg and 5 mol% or more and less than 30 mol% of La. A hydrogen storage alloy containing the element A containing specific amounts of La and Mg can improve storage characteristics. Further, from the viewpoint of low cost, it is desirable to use misch metal as the rare earth element. Here, the misch metal means a mixture of rare earth elements centered on light rare earth, and specifically, the content of La, Ce, Pr and Nd is 99% by weight or more, and the content of Ce is more than 99% by weight. 50% by weight or more and L
Examples thereof include those having an a content of 30% by weight or less (Mm) and those having a La content higher than Mm (Lm).

The element B has a heat of formation of hydride ΔH (kJ / mol) of 20 k per mole of hydrogen at 25 ° C.
At least one element of J / mol or more. The element B
It is conceivable to add various elements to the constituents of the above depending on the purpose of use of the hydrogen storage alloy. In order to facilitate release of the hydrogen occluded in the alloy, it is desirable to use an element which is difficult to spontaneously produce a hydride as the element B. In particular,
Ni, Cr, Mn, Fe, Co, Cu, Zn, Sn, S
At least one element selected from i, B, Al and Ga can be mentioned. Among them, those containing Ni are preferable. By setting the Ni content of the element B to 50 mol% or more and less than 90 mol%, the discharge characteristics of the secondary battery can be improved. A more preferable range of the Ni content of the element B is 70 mol% or more and less than 85 mol%.
In particular, those in which a part of Ni is substituted by at least one element of Co and Mn are preferable. Ni
An electrode containing a hydrogen storage alloy in which a part of the alloy is replaced with at least one element of Co and Mn can improve low-temperature discharge characteristics. In particular, substitution with Co
The low-temperature cycle characteristics of the secondary battery can be improved.

The A ₂ B ₄ subcell can have various structures, but preferably has a Laves structure. Among them, MgZn ₂ (C14) type, MgCu ₂ (C
15) type or MgNi ₂ (C36) type is preferable.

It is preferable that the AB ₅ subcell has a structure having a CaCu ₅ type. Such AB ₅ subcell having a structure, a stacked structure with the A ₂ B ₄ subcells can be easily formed. In particular, the A ₂ B ₄ subcell has a Loves structure, and the AB ₅ subcell has a C
When the aCu ₅ type is used, the occlusion characteristics of the alloy can be significantly improved.

[0294] When the relative said AB ₅ subcells number in the unit cell A ₂ B ₄ subcell ratio of the number of X (A ₂ B ₄ subcell number / AB ₅ subcell number) out of the range,
The hydrogen storage / release performance of the hydrogen storage alloy is reduced, and the discharge characteristics, particularly at low temperatures, of the electrode containing the alloy and the secondary battery including the electrode are lowered.

There are various periods for the laminated structure in the unit cell. Among them, n [LCLC
C] (where, L is A ₂ B ₄ subcell, C is AB ₅ subcell, n represents an integer) A ₂ B ₄ subcell and AB ₅ subcells are stacked unit cells in a pattern represented by are preferred. A hydrogen storage alloy containing a crystal phase composed of such a unit cell can remarkably improve hydrogen storage characteristics. Above all, by setting n to 1 or 2, the discharge characteristics of the electrode and the secondary battery can be significantly improved. In addition, when replacement with a different element is performed or the atomic arrangement is changed, good occlusion characteristics are exhibited even when the pattern has a longer period.

The above-mentioned hydrogen-absorbing alloy was prepared by a transmission electron microscope (TEM) in which the unit cells (A ₂ B ₄ sub-cells and AB ₅ sub-cells) had a specific sub-cell number ratio (0.5 <
It is preferable that the measurement rate of the layers laminated under X <1) is 0.3 or more. When the measurement rate is less than 0.3,
This is because the alloy may cause a reduction in the hydrogen storage / release performance of the alloy, and may deteriorate the charge / discharge performance of the electrode or the secondary battery. Here, the measurement rate is such that a sample obtained by cutting the hydrogen storage alloy ingot in an arbitrary direction and a sample obtained by cutting the hydrogen storage alloy ingot perpendicularly to the cut surface are prepared, and the same number is selected arbitrarily for each sample. An electron diffraction image and a lattice image are respectively measured by a transmission electron microscope (TEM), and the unit cell is obtained from the ratio of the measured points when the total number of measurement points is set to one.

Next, an example of a cylindrical metal oxide / hydrogen secondary battery of the secondary batteries according to the present invention will be described with reference to FIG.

As shown in FIG. 2, an electrode group 5 produced by laminating a positive electrode 2, a separator 3, and a negative electrode 4 and winding them into a spiral shape is accommodated in a bottomed cylindrical container 1. ing. The negative electrode 4 is arranged at the outermost periphery of the electrode group 5 and is in electrical contact with the container 1. The alkaline electrolyte is contained in the container 1. Hole 6 in the center
The first sealing plate 7 having a circular shape is disposed at the upper opening of the container 1. Ring-shaped insulating gasket 8
Is disposed between the peripheral edge of the sealing plate 7 and the inner surface of the upper opening of the container 1, and the sealing plate 7 is connected to the container 1 through the gasket 8 by caulking to reduce the diameter of the upper opening inward. And airtightly fixed. One end of the positive electrode lead 9 is connected to the positive electrode 2, and the other end is connected to the lower surface of the sealing plate 7. The positive electrode terminal 10 having a hat shape is attached on the sealing plate 7 so as to cover the hole 6.
The safety valve 11 made of rubber includes the sealing plate 7 and the positive electrode terminal 1.
It is arranged so as to close the hole 6 in a space surrounded by 0. A circular holding plate 12 made of an insulating material having a hole in the center is arranged on the positive electrode terminal 10 such that a protrusion of the positive electrode terminal 10 projects from the hole of the holding plate 12. The outer tube 13 covers the periphery of the holding plate 12, the side surface of the container 1, and the periphery of the bottom of the container 1.

Next, the positive electrode 2, the negative electrode 4, the separator 3
And the electrolyte will be described.

1) Positive electrode 2 This positive electrode 2 is prepared, for example, by adding a conductive material to nickel hydroxide powder as an active material and kneading the mixture with a polymer binder and water to prepare a paste. It is produced by filling a substrate, drying and molding.

The nickel hydroxide powder may contain an oxide or hydroxide of at least one metal selected from the group consisting of zinc and cobalt.

[0302] Examples of the conductive material include cobalt oxide, cobalt hydroxide, metallic cobalt, metallic nickel, and carbon.

Examples of the polymer binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene, and polyvinyl alcohol (PVA).

Examples of the conductive substrate include a mesh-like, sponge-like, fibrous, or felt-like porous metal body made of nickel, stainless steel, or nickel-plated metal.

2) Negative Electrode 4 This negative electrode 4 is produced, for example, by the method described in the following (1) and (2).

(1) A conductive material is added to the powder of the hydrogen storage alloy, and the mixture is kneaded with a polymer binder and water to prepare a paste. The paste is filled in a conductive substrate, dried, and then molded. Thereby, the negative electrode is manufactured.

(2) A conductive material is added to the powder of the hydrogen storage alloy, and the mixture is kneaded with a polymer binder to prepare a mixture. The mixture is held on a conductive substrate, dried, and then molded. Thereby, the negative electrode is manufactured.

As the hydrogen storage alloy, the first alloy described above is used.
Any one of the seventeenth to seventeenth hydrogen storage alloys may be used, or two or more types may be mixed and used. As a method of pulverizing the hydrogen storage alloy, for example, a mechanical pulverization method such as a ball mill, a pulverizer, a jet mill, or a method of storing and releasing high-pressure hydrogen and performing pulverization by volume expansion at that time is employed.

In the hydrogen storage alloy powder, particles having a particle size of 100 μm or more in the particle size distribution are less than 10% by weight,
It is preferable that the particles having a particle size of 10 μm or less are less than 15% by weight and the average particle size is 35 to 55 μm. According to the hydrogen storage alloy powder having such a particle size distribution, activation can be performed in a short time, and a metal oxide / hydrogen secondary battery having a long cycle life can be realized.

As the polymer binder, the same ones as used in the positive electrode 2 can be used. In the case where the negative electrode is manufactured by the method (2) described above, one containing polytetrafluoroethylene (PTFE) is preferable.

[0311] Examples of the conductive material include carbon black.

Examples of the conductive substrate include a two-dimensional substrate such as punched metal, expanded metal, and nickel net, and a three-dimensional substrate such as a felt-like metal porous body and a sponge-like metal substrate. it can.

3) Separator 3 The separator 3 is made of a polymer non-woven fabric such as a polypropylene non-woven fabric, a nylon non-woven fabric, or a non-woven fabric obtained by mixing polypropylene fibers and nylon fibers. In particular, a polypropylene nonwoven fabric whose surface has been hydrophilized is suitable as a separator.

4) Alkaline Electrolyte As the alkaline electrolyte, for example, an aqueous solution of sodium hydroxide (NaOH), lithium hydroxide (LiOH)
Aqueous solution, potassium hydroxide (KOH) aqueous solution, NaO
H and LiOH mixed solution, KOH and LiOH mixed solution, K
A mixed solution of OH, LiOH, and NaOH can be used.

In FIG. 1 described above, an example of a cylindrical metal oxide / hydrogen secondary battery was described. However, the present invention relates to an electrode group and an alkaline electrolyte prepared by interposing a separator between a positive electrode and a negative electrode. Can be similarly applied to a square metal oxide / hydrogen secondary battery having a structure housed in a bottomed rectangular cylindrical container.

The first hydrogen storage alloy according to the present invention described above is manufactured by a casting method or a sintering method and has an alloy ingot having a composition represented by the above-mentioned general formula (1), or the alloy ingot described above. Includes crushed ingot. Such a hydrogen storage alloy can increase the hydrogen equilibrium pressure and improve the hydrogen storage / release speed.

Therefore, the secondary battery provided with the negative electrode containing the hydrogen storage alloy particles containing the pulverized product of the alloy ingot can improve the operating voltage, and can greatly improve the charge / discharge capacity. , Cycle life can be improved. Also, the secondary battery can improve discharge characteristics at high temperatures.

The second hydrogen storage alloy according to the present invention is manufactured by a casting method or a sintering method, and is an alloy ingot having a composition represented by the above-mentioned general formula (2), or a crushed alloy ingot. Including things. Such a hydrogen storage alloy can increase the rate of storing and releasing hydrogen.

Therefore, a secondary battery provided with a negative electrode containing hydrogen-absorbing alloy particles containing a crushed product of the alloy ingot can significantly improve cycle life and improve discharge characteristics at high temperatures. be able to.

The third hydrogen absorbing alloy according to the present invention is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the above-mentioned general formula (3), or a crushed alloy ingot. Including things. Such a hydrogen storage alloy can greatly improve the hydrogen storage / release speed and also improve the hydrogen equilibrium pressure.

Therefore, a secondary battery provided with a negative electrode containing hydrogen-absorbing alloy particles containing a crushed product of the alloy ingot can dramatically improve both the charge / discharge capacity and the cycle life, and can be used at high temperatures. Can significantly improve the discharge characteristics.

The fourth hydrogen storage alloy according to the present invention is manufactured by a casting method or a sintering method, and is an alloy ingot having a composition represented by the general formula (4) described above, or a crushed alloy ingot. Including things. Such a hydrogen storage alloy can remarkably improve the hydrogen storage / release characteristics, particularly the hydrogen storage / release speed.

Therefore, a secondary battery provided with a negative electrode containing hydrogen-absorbing alloy particles containing a crushed product of the alloy ingot has a large discharge capacity and can improve cycle life.

The fifth hydrogen storage alloy according to the present invention is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the aforementioned general formula (5), or a crushed alloy ingot. Including things. Such a hydrogen storage alloy can remarkably improve the hydrogen storage / release characteristics, particularly the hydrogen storage / release speed.

Therefore, the secondary battery provided with the negative electrode containing the hydrogen storage alloy particles containing the pulverized product of the alloy ingot can further improve the discharge capacity and the cycle life.

The sixth hydrogen storage alloy according to the present invention is manufactured by a casting method or a sintering method, and is an alloy ingot having a composition represented by the aforementioned general formula (6), or a crushed alloy ingot. Including things. In such a hydrogen storage alloy, since a part of the nickel component is replaced with Co, the hydrogen storage / release characteristics such as the hydrogen storage / release speed can be significantly improved, and the hydrogen storage amount in the plateau region can be improved. Stabilization can be achieved.

Therefore, the secondary battery provided with the negative electrode containing the hydrogen storage alloy particles containing the pulverized alloy ingot can stabilize the voltage at the time of discharging, so that a large discharge capacity can be obtained. And cycle life can be improved.

The seventh hydrogen storage alloy according to the present invention is manufactured by a casting method or a sintering method, and is an alloy ingot having a composition represented by the above-mentioned general formula (7), or a crushed alloy ingot. Including things. Such a hydrogen storage alloy can significantly improve the hydrogen storage / release characteristics such as the hydrogen storage / release speed, and can stabilize the hydrogen storage amount in the plateau region.

Therefore, the secondary battery provided with the negative electrode containing the hydrogen storage alloy particles containing the pulverized product of the alloy ingot can stabilize the discharge voltage, so that a large discharge capacity can be obtained. Moreover, the cycle life can be improved.

The eighth hydrogen storage alloy according to the present invention is produced by a casting method or a sintering method, and is an alloy ingot having a composition represented by the aforementioned general formula (8), or a crushed alloy ingot. Including things. According to such a hydrogen storage alloy, by partially replacing the Mg component with La, the hydrogen equilibrium pressure can be increased to a desired value, and the hydrogen storage / release characteristics can be improved.

Therefore, a secondary battery provided with a negative electrode containing hydrogen-absorbing alloy particles containing a crushed product of the above-mentioned alloy ingot can improve the operating voltage, thereby improving the discharge capacity and cycle life. .

A ninth hydrogen storage alloy according to the present invention is an alloy ingot produced by a casting method or a sintering method and having a composition represented by the aforementioned general formula (9), or a crushed alloy ingot. Including things. According to such a hydrogen storage alloy, by replacing the rare earth component R with the above-described specific amount with La and replacing the Ni component with the above-described specific amount with M, the hydrogen equilibrium pressure, the hydrogen storage / release characteristics and Corrosion resistance can be satisfied at the same time.

Therefore, a secondary battery provided with a negative electrode containing hydrogen-absorbing alloy particles containing a crushed product of the above-mentioned alloy ingot greatly improved cycle characteristics due to the synergistic effect of the rare earth components R containing La and the Ni component containing M. Can be improved.

The tenth hydrogen storage alloy according to the present invention includes an alloy having a composition represented by the above-mentioned formula (10).
Such a hydrogen storage alloy has a Ce content in R2 of 20%.
Since the content is less than 10% by weight, corrosion resistance can be enhanced while maintaining a preferable crystal structure, and excellent hydrogen storage / release performance can be maintained even in a high temperature environment. When the negative electrode containing the alloy is incorporated in a secondary battery, a secondary battery having high capacity and long life even in a high-temperature environment can be realized.

The hydrogen storage alloy of the tenth hydrogen storage alloy according to the present invention further impairs the corrosion resistance of the hydrogen storage alloy by adding La to R2 and increasing the La content in R2 to more than 70% by weight. And the amount of hydrogen occlusion / release can be improved. Therefore, the secondary battery including the negative electrode containing the alloy can further improve the discharge capacity and the cycle life.

An eleventh hydrogen storage alloy according to the present invention includes an alloy having a composition represented by the above formula (11).
Such a hydrogen storage alloy is obtained according to the above-mentioned formula (I).
Since the upper limit of the amount of Ce is set according to the amount of Co, the corrosion resistance can be increased while maintaining a preferable crystal structure, and excellent hydrogen storage / release performance can be maintained even in a high temperature environment. When the negative electrode containing the alloy is incorporated in a secondary battery, a secondary battery having high capacity and long life even in a high-temperature environment can be realized.

The twelfth hydrogen storage alloy according to the present invention has a composition represented by the above-mentioned general formula (12), and a and z in the general formula (12) satisfy the above-mentioned formula (II). Since a crystal phase having a composition is a main phase and an alloy in which the number of plane defects in the main phase is 20 or less per 100 nm is included, it is difficult to release hydrogen while having a high hydrogen storage amount. Problems can be solved, and hydrogen storage / release characteristics such as hydrogen storage / release speed can be significantly improved.

Accordingly, a secondary battery provided with a negative electrode containing the above alloy has a large discharge capacity and can improve cycle characteristics.

The thirteenth hydrogen storage alloy according to the present invention has a composition represented by the aforementioned general formula (13), and a and z in the aforementioned general formula (13) satisfy the aforementioned formula (II). The crystal phase having the composition is the main phase, and the number of plane defects is 1
Since it contains an alloy containing more than 70% by volume of crystal grains of not more than 20 grains per 00 nm, it is possible to improve the problem of difficulty in releasing hydrogen while having a high hydrogen storage amount. -Hydrogen storage / release characteristics such as release rate can be significantly improved.

Accordingly, a secondary battery provided with a negative electrode containing the above alloy has a large discharge capacity and can improve cycle characteristics.

The fourteenth hydrogen storage alloy according to the present invention has a composition represented by the aforementioned general formula (14), and a and z in the aforementioned general formula (14) are represented by the aforementioned formula (II). a crystal phase main phase having a composition that is, a crystal phase having a CaCu ₅ type crystal structure in 20% by volume or less, and MgC
Since it contains an alloy in which the crystal phase having the u ₂ type crystal structure is 10% by volume or less, the hydrogen storage / release characteristics such as the hydrogen storage / release speed can be improved. Therefore, a secondary battery provided with a negative electrode containing the alloy has a large discharge capacity and can improve cycle life.

Further, in the fourteenth hydrogen storage alloy, the crystal phase having a CaCu ₅ type crystal structure is set to 10% by volume or less and the crystal phase having a MgCu ₂ type crystal structure is set to 5% by volume or less. To further improve the hydrogen storage / release characteristics, and in particular to remarkably improve the cycle characteristics, thereby realizing a metal oxide / hydrogen secondary battery having significantly improved discharge capacity and cycle life. Can be.

A fifteenth hydrogen storage alloy according to the present invention comprises:
It is represented by the general formula (15), and is a Ce ₂ Ni ₇ type, C
eNi ₃ type, Gd ₂ Co ₇ type, PuNi ₃ type or at least one phase selected from a phase having a similar crystal structure or an alloy containing a main phase,
Hydrogen storage / release characteristics such as hydrogen storage / release speed are significantly improved.

The secondary battery having the fifteenth negative electrode containing a hydrogen storage alloy has a high capacity and excellent charge / discharge cycle characteristics because the hydrogen storage alloy has excellent hydrogen storage / release characteristics.

The sixteenth hydrogen storage alloy according to the present invention comprises:
The intensity (I ₁ ) of the strongest peak represented by the general formula (16) and appearing in the range of 2θ = 8 to 13 ° in the X-ray diffraction pattern using CuKα radiation, and the intensity of the strongest peak of all peaks (I ₁ ) I ₂ ) and an intensity ratio (I ₁ / I ₂ ) of 0.1
Since the alloy containing less than 5 is included, the hydrogen storage / release characteristics can be improved.

The secondary battery including the negative electrode containing the sixteenth hydrogen storage alloy has high capacity and excellent charge / discharge cycle characteristics because the hydrogen storage alloy has excellent hydrogen storage / release characteristics.

A seventeenth hydrogen storage alloy according to the present invention
It has a laminated structure of ₂ B ₄ subcells and AB ₅ subcells,
And a crystal phase composed of unit cells in which the ratio X of the number of A ₂ B ₄ subcells to the number of AB ₅ subcells is 0.5 <X <1. According to such a hydrogen storage alloy, excellent hydrogen storage / release characteristics can be realized even at low temperatures. Further, a secondary battery including an electrode containing the alloy and the electrode as a negative electrode can achieve high discharge capacity and long life even in a low-temperature environment.

In the above hydrogen storage alloy, (1) the above A
The ₂ B ₄ subcell Laves structure, and to the AB ₅ subcell CaCu ₅ type or, or (2) said unit cell is n [LCLCC] (where, L is A ₂ B ₄ subcell, C is AB ₅ subcells , N represents an integer), and particularly the occlusion characteristics of the alloy can be improved. Therefore, a secondary battery including an electrode containing the alloy and the electrode as a negative electrode can improve discharge capacity and cycle life especially in a low-temperature environment. In particular, the hydrogen storage alloy is preferably (1)
By satisfying both conditions (2) and (2), the occlusion characteristics of the alloy and the low-temperature charge / discharge characteristics of the electrode and the secondary battery can be drastically improved.

In the hydrogen storage alloy, A is at least one element selected from rare earth elements containing Y and M
By containing g and B containing Ni, the hydrogen storage / release characteristics of the alloy can be further improved. Therefore, the secondary battery including the electrode containing the alloy and the electrode as the negative electrode can further improve the discharge capacity and the cycle life.

[0350]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

FIG. 3 is a schematic view showing a temperature scanning type hydrogen storage / release characteristic evaluation apparatus used for evaluating a hydrogen storage alloy. The hydrogen cylinder 31 is connected to a sample container 33 through a pipe 32. The pipe 32 is branched on the way, and an end of the branch pipe 34 is connected to a vacuum pump 35. The pressure gauge 36 is attached to a pipe portion 34a further branched from the branch pipe 34.
Piping 32 between the hydrogen cylinder 31 and the sample container 33
The first and second valves 3 from the cylinder 31 side
7 _1, 37 ₂ is interposed. The accumulator 38 is connected to the pipe 32 between the _first and _second valves 37 ₁ and 37 ₂ . The vacuum pump 35 is connected to the branch pipes 34a through the third valve 37 _3. The heater 39 is attached to the sample container 33. The thermocouple 40 is inserted into the sample container 33. A temperature controller 42 controlled by a computer 41 is connected to the thermocouple 40 and the heater 39, and adjusts the temperature of the heater 39 based on the temperature detected from the thermocouple 40. The recorder 43 controlled by the computer 41 is connected to the pressure gauge 36 and the temperature controller 42.

(Examples 1 to 8 and Comparative Examples 1 and 2) Each element was weighed so as to have the composition shown in Table 1 below, and melted in a high-frequency melting furnace in an argon gas atmosphere to obtain a hydrogen storage alloy ingot. Was prepared. Each of the obtained alloy ingots was pulverized to a particle size of 125 μm or less.

(Comparative Example 3) Each element was weighed so as to have the composition shown in Table 1 below, and an alloy ingot was produced by high-frequency melting under an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to produce a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was heated at 890 ° C for 1 hour.
After a heat treatment of 2 hours under an argon atmosphere,
The powder was pulverized to 25 μm or less to prepare a hydrogen storage alloy powder.

Next, the hydrogen storage alloy powders of Examples 1 to 8 and Comparative Examples 1 to 3 were stored in the above-described sample container 33 (atmospheric temperature of 80 ° C.) of FIG. Closing the first valve 37 _1, No. 2, opens the third valve 37 _2, 37 _3, and exhausting air of the pipe 32 and branch pipe 34 and the accumulator vessel 38 by operating the vacuum pump 35. After closing the second and third valves 37 ₂ and 37 ₃ , the first valve 37 ₁ is opened to supply hydrogen from the hydrogen cylinder 31 and supply the hydrogen to the pipe 32.
The inside of the branch pipe 34 and the pressure storage vessel 38 was replaced with hydrogen. Subsequently, closing the first valve 37 ₁ was calculated amount of hydrogen was introduced from the pressure in the system indicated by the pressure gauge 36 at this time. Subsequently, the second opening the valve 37 _2, hydrogen was supplied into the sample container 33, to monitor the temperature at the thermocouple 40. Thereafter, the temperature was controlled by the computer 41 and the temperature controller 42 so that the temperature in the sample container 33 was constant. At this time, the pressure change in the container 33 was detected by the pressure gauge 36 and recorded by the recorder 43.

As described above, the amount of hydrogen (H / M) occluded in each of the hydrogen storage alloys until one hour after the introduction of a fixed amount of hydrogen into the sample container 33 was determined by the pressure in the container 33. The hydrogen absorption rate (H
/ M · h ⁻¹ ) in Table 1 below.

[0356]

[Table 1]

As is clear from Table 1, the hydrogen storage alloys of Examples 1 to 8 produced by the casting method and having the composition represented by the general formula (1) have a hydrogen storage rate at 80 ° C. It turns out that it is higher than the hydrogen storage alloys of Comparative Examples 1 to 3.

The low hydrogen storage rate of the hydrogen storage alloy of Comparative Example 1 is due to the fact that it is a La _1-x Mg _x Ni ₂ type alloy. Further, the hydrogen storage alloy of Comparative Example 3 has the same composition as that of Example 8, but has a lower hydrogen storage speed than that of Example 8. This is because it was manufactured by the molten metal quenching method.

(Examples 9 to 15 and Comparative Example 4) Each element was weighed so as to have the composition shown in Table 2 below and melted in a high-frequency melting furnace in an argon gas atmosphere to produce a hydrogen storage alloy ingot. did. Each of the obtained alloy ingots was pulverized to a particle size of 125 μm or less.

(Comparative Example 5) Each element was weighed so as to have the composition shown in Table 2 below, and an alloy ingot was produced by high frequency melting under an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to produce a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was heated at 890 ° C for 1 hour.
After a heat treatment of 2 hours under an argon atmosphere,
The powder was pulverized to 25 μm or less to prepare a hydrogen storage alloy powder.

The hydrogen storage alloy powders of Examples 9 to 15 and Comparative Examples 4 to 5 were prepared in the same manner as described above.
The hydrogen storage rate (H / M · h ⁻¹ ) at 0 ° C. was measured, and the results are also shown in Table 2 below.

[0362]

[Table 2]

As is clear from Table 2, the hydrogen storage alloys of Examples 9 to 15 manufactured by the casting method and having the composition represented by the general formula (2) have a hydrogen storage rate at 80 ° C. It can be seen that it is higher than the hydrogen storage alloys of Comparative Examples 4 and 5. The hydrogen storage alloy of Comparative Example 5 has the same composition as that of Example 13, but has a lower hydrogen storage rate than that of Example 13. This is because it was manufactured by the molten metal quenching method.

(Examples 16 to 22 and Comparative Examples 6 to 8) Each element was weighed so as to have the composition shown in Table 3 below, sintered in an argon gas atmosphere, and then heat-treated near the melting point to absorb hydrogen. An alloy ingot was produced. The obtained alloy ingots were each pulverized to a particle size of 75 μm or less.

(Comparative Example 9) Each element was weighed so as to have the composition shown in Table 3 below, and an alloy ingot was produced by high frequency melting under an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to produce a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was heated at 890 ° C for 1 hour.
After a heat treatment for 2 hours in an argon atmosphere, the particle size is 7
The powder was pulverized to 5 μm or less to produce a hydrogen storage alloy powder.

For the hydrogen storage alloy powders of Examples 16 to 22 and Comparative Examples 6 to 9, the hydrogen storage rate (H / M · h ⁻¹ ) at 80 ° C. was measured by the same method as described above. The results are shown in Table 3 below.

[0367]

[Table 3]

As is clear from Table 3, the hydrogen storage alloys of Examples 16 to 22 produced by the sintering method and having the composition represented by the general formula (3) have a hydrogen storage rate at 80 ° C. Is higher than the hydrogen storage alloys of Comparative Examples 6 to 9.

The low hydrogen storage rate of the hydrogen storage alloy of Comparative Example 6 is attributable to the fact that it is a La _1-x Mg _x Ni ₃ series alloy. The hydrogen storage alloy of Comparative Example 9 has the same composition as that of Example 20, but has a lower hydrogen storage rate than that of Example 20. This is because it was manufactured by the molten metal quenching method.

(Examples 23 to 44 and Comparative Examples 10 to 1)
3,15,17～18) RNi ₅ system is relatively high melting point alloy system, RNi ₃ system, RNi ₂ system, and RNi based master alloy, a MgNi ₂ based mother alloy by a high frequency melting furnace (argon atmosphere) Produced. Each of the obtained master alloys is shown in Table 4 below.
6 were weighed so as to have the compositions shown in Nos. 6 to 6, and sintered at a high temperature in an argon gas atmosphere to produce an alloy ingot. Each of the obtained alloy ingots has a particle size of 75 μm.
m or less.

(Comparative Examples 14, 16, and 19) Each element was weighed so as to have the composition shown in Tables 4 to 6 below, and an alloy ingot was produced by high-frequency melting in an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to produce a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was subjected to a heat treatment at 890 ° C. for 12 hours in an argon atmosphere, and then pulverized to a particle size of 75 μm or less to prepare a hydrogen storage alloy powder.

The obtained Examples 23 to 44 and Comparative Example 10
Electrodes were produced from the hydrogen storage alloy powders Nos. 1 to 19 by the procedure described below. First, each alloy powder and electrolytic copper powder were mixed at a weight ratio of 1: 1 and 1 g of this mixture was pressured at 10,000 k using a tableting machine (inner diameter 10 mm).
A pellet was produced by applying pressure for 5 minutes under the condition of gf / cm ² . An alloy electrode (negative electrode) was produced by sandwiching the pellet between nickel meshes, spot welding the periphery, and spot welding a nickel lead wire.

Each of the obtained negative electrodes was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode to form a negative electrode capacity regulated battery.
A charge / discharge cycle test was performed at a temperature of ° C., and the maximum discharge capacity and the number of cycles (the number of cycles when the discharge capacity decreased to 80% of the maximum discharge capacity) were measured. The charge and discharge conditions were 10 mA at a current of 100 mA per g of the hydrogen storage alloy.
After charging the battery for 10 hours, the battery was suspended for 10 minutes, and a current of 20 mA per 1 g of the hydrogen storage alloy was applied to the mercury oxide electrode at -0.5 V
The cycle of discharging until was reached. The results are shown in Tables 4 to 6 below.

[0374]

[Table 4]

[0375]

[Table 5]

[0376]

[Table 6]

As is apparent from Table 4, the nickel-hydrogen secondary batteries of Examples 23 to 28, which were manufactured by the sintering method and had the composition represented by the general formula (1), It can be seen that both the maximum discharge capacity and the cycle life are superior to the secondary battery of No. 14. Comparative Example 10
Both the discharge capacity and the cycle life of the secondary batteries of Nos. 1 to 12 were inferior because the hydrogen storage alloy of the negative electrode was La _1-X Mg _X Ni ₂
This is because a system alloy or La _{1- X} Mg _X Ni ₃ type alloy. On the other hand, in the secondary battery of Comparative Example 14, although the composition of the hydrogen storage alloy contained in the negative electrode was the same as that of Example 25, both the discharge capacity and the cycle life were inferior to Example 25. This is because the hydrogen storage alloy was manufactured by a molten metal quenching method.

As is clear from Table 5, the nickel-metal hydride secondary batteries of Examples 29 to 35 manufactured by the sintering method and having the composition represented by the general formula (2) were compared with Comparative Example 15, It can be seen that both the maximum discharge capacity and the cycle life are superior to those of the 16 secondary batteries. In the secondary battery of Comparative Example 16, although the composition of the hydrogen storage alloy contained in the negative electrode was the same as that of Example 32, both the discharge capacity and the cycle life were inferior to Example 32. This is because the hydrogen storage alloy was manufactured by a molten metal quenching method.

As is clear from Table 6, the nickel-hydrogen secondary batteries of Examples 36 to 44 produced by the sintering method and having the composition represented by the general formula (3) were prepared in Comparative Examples 10 to 44. It can be seen that both the maximum discharge capacity and the cycle life are remarkably superior to the secondary batteries of Nos. 12, 17 to 19. In the secondary battery of Comparative Example 19, although the composition of the hydrogen storage alloy contained in the negative electrode was similar to that of Example 40, both the discharge capacity and the cycle life were inferior to Example 40. This is because the hydrogen storage alloy was manufactured by a molten metal quenching method.

(Examples 45 to 55 and Comparative Examples 20 to 2)
1) Each element is weighed so as to have a composition shown in Table 7 below,
Thirteen kinds of alloy ingots were obtained by melting in a high-frequency induction furnace in an atmosphere of argon. Subsequently, these alloy ingots were subjected to a heat treatment at 950 ° C. for 3 hours in an argon atmosphere. The obtained alloy ingot was treated with a particle size of 15
Each of the powders was pulverized to have a particle size of 0 μm or less to prepare a hydrogen storage alloy powder. Note that the misch metal (L
m) is 84 at% La, 10 at% Ce, 1 at
% Pr, 5 at% Nd and 0.2 at% Sm. The misch metal (Mm) is 2
7.5 at% La, 50.3 at% Ce, 5.5 a
It consists of t% Pr, 16.5 at% Nd and 0.2 at% Sm.

The hydrogen storage alloy powder and the electrolytic copper powder were mixed at a weight ratio of 1: 2, and 1 g of the mixture was pressed at a pressure of 10 tons / cm ² for 5 minutes to form a mixture having a diameter of 12 mm. Thirteen types of pellets were produced.
These pellets were sandwiched between nickel wire meshes, and the periphery of the wire mesh was spot-welded and pressure-welded, and further, nickel leads were spot-welded to the wire mesh to produce 13 types of hydrogen storage electrodes (negative electrodes). .

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte) in a container together with a sintered nickel electrode as a counter electrode, and the test cells (Examples 45 to 55 and Comparative Examples 20 to 55) were used.
21) was assembled.

(Comparative Example 22) A test cell similar to that of Examples 45 to 55 was assembled except that the hydrogen storage alloy powder described below was used.

Each element was weighed so as to have the composition shown in Table 7 below, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Subsequently, these alloy ingots were melted, and the obtained molten metal was heated at 5 m / sec in an argon atmosphere.
The resultant was dropped on the surface of a copper single roll rotating at a peripheral speed of c and rapidly cooled to produce a flake-shaped hydrogen storage alloy. Continued,
Each flaky hydrogen storage alloy was subjected to a heat treatment at 890 ° C. for 12 hours in an argon atmosphere, and then pulverized to a particle size of 150 μm or less to prepare a hydrogen storage alloy powder.

The obtained Examples 45 to 55 and Comparative Example 20
A charge / discharge cycle test was performed on the test cells Nos. To 22 at a temperature of 25 ° C. The charge / discharge conditions were 1 g of hydrogen storage alloy.
After charging for 5 hours at a current of 100 mA per hour and resting for 10 minutes, a cycle of discharging at a current of 50 mA per 1 g of the hydrogen storage alloy to -0.6 V with respect to the mercury oxide electrode was repeated, and the maximum discharge capacity and the cycle were repeated. Life (number of cycles when discharge capacity drops to 80% of maximum discharge capacity)
Was measured. The results are shown in Table 7 below.

Examples 45 to 55 and Comparative Examples 20 to 55
The hydrogen storage properties of the hydrogen storage alloy No. 22 were measured at 60 ° C. by 1 according to the Siebert's method (JIS H7201).
The pressure-composition isotherm was measured under a hydrogen pressure of less than 0 atm, and the effective hydrogen storage amount (JIS H7003 hydrogen storage alloy term) was determined. The results are shown in Table 7 below.

[0387]

[Table 7]

As is clear from Table 7, the hydrogen storage alloys of Examples 45 to 55 produced by the casting method and having the composition represented by the general formula (4) were compared with Comparative Examples 20 to 22.
It can be seen that the effective hydrogen storage amount is larger than that of the hydrogen storage alloy of Example 1.

Further, the secondary batteries provided with the negative electrodes containing the hydrogen storage alloys of Examples 45 to 55 had a discharge capacity and cycle compared with the secondary batteries provided with the negative electrodes containing the hydrogen storage alloys of Comparative Examples 20 to 22. It can be seen that the life can be improved.

(Examples 56 to 65 and Comparative Examples 23 to 2)
4) Each element is weighed to have a composition shown in Table 8 below,
The alloy was melted in a high-frequency induction furnace in an argon atmosphere, poured into a water-cooled copper mold, and solidified to prepare an alloy ingot. Subsequently, these alloy ingots were added at 950 ° C. for 3 hours.
Time heat treatment was performed under an argon atmosphere. The obtained alloy ingots were each pulverized so as to have a particle size of 150 μm or less to prepare a hydrogen storage alloy powder. The misch metal (Lm) in Table 8 is 90 at% La, 1a
It is composed of t% Ce, 6 at% Pr, and 3 at% Nd. The misch metal (Mm) is 34
at% La, 50.8 at% Ce, 8 at% P
r, 7 at% Nd and 0.2 at% Sm.

The hydrogen storage alloy powder and the electrolytic copper powder were mixed at a weight ratio of 1: 3, and 1 g of the mixture was pressed at a pressure of 8 tons / cm ² for 8 minutes to obtain a 10 mm diameter. Twelve kinds of pellets were produced. These pellets were sandwiched between nickel wire meshes, and the periphery of the wire mesh was spot-welded and pressure-welded, and further, nickel leads were spot-welded to the wire mesh to produce 12 types of hydrogen storage electrodes (negative electrodes). .

Each of the obtained negative electrodes together with a sintered nickel electrode as a counter electrode was immersed in a 6N-KOH aqueous solution (electrolyte solution) in a container, and the test cells (Examples 56-65 and Comparative Examples 23-65) were immersed.
24) was assembled.

(Comparative Example 25) A test cell similar to that of Examples 56 to 65 was assembled except that the hydrogen storage alloy powder described below was used.

Each element was weighed so as to have the composition shown in Table 8 below, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Subsequently, these alloy ingots were melted, and the obtained molten metal was heated at 5 m / sec in an argon atmosphere.
The resultant was dropped on the surface of a copper single roll rotating at a peripheral speed of c and rapidly cooled to produce a flake-shaped hydrogen storage alloy. Continued,
Each flaky hydrogen storage alloy was subjected to a heat treatment at 890 ° C. for 12 hours in an argon atmosphere, and then pulverized to a particle size of 150 μm or less to prepare a hydrogen storage alloy powder.

The obtained Examples 56 to 65 and Comparative Example 23
A charge / discharge cycle test was performed at a temperature of 25 ° C. on the test cells of No. to 25. The charge / discharge conditions were 1 g of hydrogen storage alloy.
After charging for 3 hours at a current of 200 mA per hour and resting for 10 minutes, a cycle of discharging at a current of 100 mA per gram of the hydrogen storage alloy to -0.55 V with respect to the mercury oxide electrode was repeated, and the maximum discharge capacity and the cycle were repeated. The life (the number of cycles when the discharge capacity was reduced to 80% of the maximum discharge capacity) was measured. The results are shown in Table 8 below.

In addition, Examples 56 to 65 and Comparative Examples 23 to
About 25 hydrogen storage alloys, the hydrogen storage properties were 1 at 45 ° C. by the Siebert's method (JIS H7201).
The pressure-composition isotherm was measured under a hydrogen pressure of less than 0 atm, and the effective hydrogen storage amount (JIS H7003 hydrogen storage alloy term) was determined. The results are shown in Table 8 below.

[0397]

[Table 8]

As is clear from Table 8, the hydrogen storage alloys of Examples 56 to 65 produced by the casting method and having the composition represented by the general formula (5) were compared with Comparative Examples 23 to 25.
It can be seen that the effective hydrogen storage amount is larger than that of the hydrogen storage alloy of Example 1.

Also, the secondary batteries provided with the negative electrodes containing the hydrogen storage alloys of Examples 56 to 65 had a higher discharge capacity and cycle compared with the secondary batteries provided with the negative electrodes containing the hydrogen storage alloys of Comparative Examples 23 to 25. It can be seen that the life can be improved.

(Examples 66 to 68 and Comparative Example 26) Each element was weighed so as to have the composition shown in Table 9 below, dissolved in a high-frequency induction furnace in an atmosphere of argon, and poured into a water-cooled copper mold. By solidifying, four kinds of alloy ingots were produced. Subsequently, these alloy ingots were subjected to a heat treatment at 950 ° C. for 3 hours in an argon atmosphere. The obtained alloy ingots were each pulverized so as to have a particle size of 150 μm or less to prepare a hydrogen storage alloy powder. The misch metal (Lm) in Table 9 is the same as that described in Table 8 described above.

From these hydrogen storage alloy powders, Examples 56 to
A hydrogen storage electrode (negative electrode) was produced in the same manner as in Example 65.

Each of the obtained negative electrodes together with a sintered nickel electrode as a counter electrode was immersed in a 6N-KOH aqueous solution (electrolyte solution) in a container, and a test cell was prepared (Examples 66 to 68 and Comparative Example 26).
Was assembled.

The obtained Examples 66 to 68 and Comparative Example 26
A charge-discharge cycle test was performed on the test cell at a temperature of 25 ° C., and the maximum discharge capacity and cycle life (the number of cycles when the discharge capacity decreased to 80% of the maximum discharge capacity)
Was measured. The results are shown in Table 9 below. The charge and discharge conditions were the same as in Examples 56 to 65.

For the hydrogen storage alloys of Examples 66 to 68 and Comparative Example 26, a pressure-composition isotherm was measured at 45 ° C. under a hydrogen pressure of less than 10 atm by the Siebert's method (JIS H7201). Then, the effective hydrogen storage amount (JIS H7003 hydrogen storage alloy term) was determined. The results are shown in Table 9 below.

[0405]

[Table 9]

As is clear from Table 9, the amount of Ca was 0.3
It can be seen that the following hydrogen storage alloys of Examples 66 to 68 have a larger effective hydrogen storage amount than the alloy of Comparative Example 26 in which the Ca amount exceeds 0.3. In addition, it can be seen that the secondary batteries of Examples 66 to 68 have higher discharge capacity and cycle life than the secondary batteries of Comparative Example 26.

(Examples 69 to 78) Each element is shown in Table 10 below.
Was weighed so as to have the composition shown in Table 1 and melted in a high-frequency induction furnace in an atmosphere of argon to obtain 10 kinds of alloy ingots. Then, 95% of these alloy ingots
Heat treatment was performed at 0 ° C. to 1000 ° C. for 5 hours under an argon atmosphere. The misch metal (Lm) in Table 10
Is 92 at% La, 4 at% Ce, 1 at% P
r and 3 at% Nd.

[0408] Each of the obtained alloy ingots was made to have a particle size of 100 µm.
m or less to prepare a hydrogen storage alloy powder. The weight ratio of each hydrogen storage alloy powder and electrolytic copper powder is 1:
2 and 1 g of each mixture is 10 ton / cm
A pellet having a diameter of 12 mm was prepared by applying a pressure of ² for 5 minutes. Each pellet is sandwiched between nickel wire meshes, and the periphery of the wire mesh is spot welded and pressed,
Further, a hydrogen storage electrode (negative electrode) was manufactured by spot welding a nickel lead to the wire mesh.

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte solution) in a container together with a sintered nickel electrode as a counter electrode to assemble a test cell.

A charge / discharge cycle test was performed at a temperature of 20 ° C. on the test cells of Examples 69 to 78 obtained.
The charge and discharge conditions were as follows: the battery was charged at a current of 200 mA per 1 g of the hydrogen storage alloy for 2.5 hours, paused for 10 minutes, and then with respect to the mercury oxide electrode at a current of 100 mA per 1 g of the hydrogen storage alloy.
The cycle of discharging until the voltage reached 0.7 V was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity decreased to 80% of the maximum discharge capacity) were measured. The results are shown in Table 11 below.

[0411] The hydrogen storage alloys of Examples 69 to 78 were evaluated for hydrogen storage properties by the Siebeltz method (JIS).
H7201), the pressure-composition isotherm was measured at a temperature of 50 ° C. under a hydrogen pressure of less than 10 atm, and the slope of the plateau when releasing hydrogen (JIS H7003 hydrogen storage alloy term: here, the straight line in the plateau region was defined as / M) = 0 and (H
/ M) = 1 when the hydrogen pressure is extended to P ₀ and P
₁ and the ratio of this hydrogen pressure P ₀ to P ₁ ) was measured. Further, hysteresis (JIS H7003 hydrogen storage alloy term: here, the ratio of the hydrogen storage pressure (P _A ) to the hydrogen release pressure (P _D ) at the center of the plateau region) was determined. These results are also shown in Table 11 below.

[0412]

[Table 10]

[0413]

[Table 11]

As is clear from Tables 10 to 11, the hydrogen storage alloys of Examples 69 to 78 have both small plateau slope and hysteresis, and have excellent characteristics. Example 6 including a negative electrode containing the alloy
It can be seen that the secondary batteries 9 to 78 have a high discharge capacity and a long cycle life. In particular, the secondary battery of Example 69 including the negative electrode including the alloy containing Co had a longer cycle life than the secondary batteries of Examples 73 and 74 including the negative electrode including the alloy containing no Co. It can be seen that the plateau slope and hysteresis of the hydrogen storage alloy are small. Further, the secondary battery of Example 75 including the negative electrode containing the alloy having the Co amount of 0.5 was compared with the secondary battery of Example 76 including the negative electrode including the alloy having the Co amount of more than 0.5. Thus, it can be seen that the cycle life is long and the plateau slope and hysteresis of the hydrogen storage alloy are small. Example 77 provided with a negative electrode containing an alloy having an Mn amount of 0.2.
Has a longer cycle life than the secondary battery of Example 78 including a negative electrode containing an alloy having an Mn amount exceeding 0.2, and a difference is seen in the slope of the plateau and the hysteresis of the alloy. I understand.

(Examples 79 to 93)
Was weighed so as to have the composition shown in Table 1 and melted in a high-frequency induction furnace in an atmosphere of argon to obtain 15 kinds of alloy ingots. Then, 95% of these alloy ingots
Heat treatment was performed at 0 ° C. to 1000 ° C. for 5 hours under an argon atmosphere. The composition of the misch metal (Lm) in Table 12 is 92 at% La, 4 at% Ce, 1 at%
And 3 at% of Nd. The composition of the misch metal (Mm) is 37.5 at% of La, 4
5.3 at% Ce, 5.5 at% Pr, 11.5 a
It consists of t% Nd and 0.2 at% Sm.

Each of the obtained alloy ingots was made to have a particle size of 100 μm.
m or less to prepare a hydrogen storage alloy powder. The weight ratio of each hydrogen storage alloy powder and electrolytic copper powder is 1:
2 and 1 g of each mixture is 10 ton / cm
A pellet having a diameter of 12 mm was prepared by applying a pressure of ² for 5 minutes. Each pellet is sandwiched between nickel wire meshes, and the periphery of the wire mesh is spot welded and pressed,
Further, a hydrogen storage electrode (negative electrode) was manufactured by spot welding a nickel lead to the wire mesh.

[0417] Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte solution) in a container together with a sintered nickel electrode as a counter electrode to assemble a test cell.

A charge / discharge cycle test was performed on the obtained test cells of Examples 79 to 93 at a temperature of 20 ° C.
The charge and discharge conditions were as follows: the battery was charged at a current of 200 mA per 1 g of the hydrogen storage alloy for 2.5 hours, paused for 10 minutes, and then with respect to the mercury oxide electrode at a current of 100 mA per 1 g of the hydrogen storage alloy.
The cycle of discharging until the voltage reached 0.7 V was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity decreased to 80% of the maximum discharge capacity) were measured. The results are shown in Table 12 below.

[0419]

[Table 12]

As is clear from Table 12, Examples 79 to
It can be seen that the secondary battery of No. 93 has a high discharge capacity and a long cycle life. In addition, the secondary battery of Example 91 including a negative electrode including a hydrogen storage alloy in which La is contained in the rare earth element component and the ratio of the rare earth component other than La is less than 0.9, the La in the rare earth component is The secondary battery of Example 89 provided with the negative electrode containing the hydrogen storage alloy having a ratio of 0.1, the secondary battery of Example 90 provided with the negative electrode containing the hydrogen storage alloy containing no La in the rare earth component, and the rare earth element It can be seen that the discharge capacity and the cycle life are superior to the secondary battery of Example 80 including the negative electrode containing the hydrogen storage alloy whose components are all La.

(Examples 94 to 108) Each element was weighed so as to have the composition shown in Table 13 below, melted in a high frequency induction furnace in an argon atmosphere, and heat-treated in an argon gas atmosphere at 950 ° C. for 5 hours. And 15 kinds of alloy ingots were obtained. The misch metal (Lm) in Table 13 is 92
at% La, 1 at% Ce, 5 at% Pr and 2
It consists of at% Nd. The misch metal (Mm) is La at 34 at% and C at 50.4 at%.
e, 9 at% Pr, 6 at% Nd and 0.6 at%
Of Sm.

Each of the obtained alloy ingots was made to have a particle size of 80 μm.
Pulverization was performed as described below to produce a hydrogen storage alloy powder. The weight ratio of each hydrogen storage alloy powder and electrolytic copper powder is 1:
3 of each mixture, and 1 g of the mixture
By pressing for 8 minutes at a pressure of ton / cm ² ,
A 0 mm pellet was prepared. Each pellet was sandwiched between nickel metal meshes, the periphery of the metal mesh was spot-welded and pressed, and a nickel lead was spot-welded to the metal mesh to produce a hydrogen storage electrode (negative electrode).

A test cell was assembled by immersing each of the obtained negative electrodes together with a sintered nickel electrode as a counter electrode in an aqueous 8N-KOH solution (electrolyte solution) in a container.

A charge / discharge cycle test was performed on the test cells of Examples 94 to 108 at a temperature of 25 ° C. The charge and discharge conditions are as follows: charge at a current of 100 mA per 1 g of the hydrogen storage alloy for 4.5 hours, pause for 10 minutes, and discharge at a current of 100 mA per 1 g of the hydrogen storage alloy until it reaches -0.7 V with respect to the mercury oxide electrode. Was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity was reduced to 80% of the maximum discharge capacity) were measured. The results are shown in Table 13 below.

[0425]

[Table 13]

As is clear from Table 13, Examples 94 to
It can be seen that the secondary battery of No. 108 has a high discharge capacity and a long cycle life.

(Examples 109 to 117) <Evaluation of Electrodes> Nine kinds of alloy ingots were obtained by weighing each element so as to have the composition shown in Table 14 below and melting it in a high frequency induction furnace in an argon atmosphere. Was. Then,
The alloy ingot except for Example 117 was subjected to a heat treatment at 1000 ° C. for 5 hours in an argon atmosphere.

Each of the obtained alloy ingots was made to have a particle size of 75 μm.
The powder was ground as follows to prepare a hydrogen storage alloy powder. The weight ratio of each hydrogen storage alloy powder and electrolytic copper powder is 1:
3, and 1 g of each mixture is 10 tons / cm.
Pellets were produced with a diameter of 10mm by pressed for 5 minutes with a ^second pressure. Each pellet is sandwiched between nickel wire meshes, and the periphery of the wire mesh is spot welded and pressed,
Further, a hydrogen storage electrode (negative electrode) was manufactured by spot welding a nickel lead to the wire mesh.

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolytic solution) in a container together with a sintered nickel electrode as a counter electrode to assemble a test cell.

(Comparative Example 27) A test cell similar to that of Examples 109 to 117 was assembled except that the hydrogen storage alloy powder described below was used.

Each element was weighed so as to have the composition shown in Table 14 below, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Subsequently, these alloy ingots were melted, and the obtained molten metal was heated at 5 m / s in an argon atmosphere.
It was dropped on the surface of a copper single roll rotating at a peripheral speed of ec and rapidly cooled to produce a flake-shaped hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was subjected to a heat treatment at 890 ° C. for 12 hours in an argon atmosphere, and then pulverized to a particle size of 75 μm or less to prepare a hydrogen storage alloy powder.

The test cells of Examples 109 to 117 and Comparative Example 27 were subjected to a charge / discharge cycle test at a temperature of 25 ° C. The charge and discharge conditions are as follows: charge at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours, pause for 10 minutes, and then discharge at a current of 50 mA per 1 g of the hydrogen storage alloy to -0.6 V with respect to the mercury oxide electrode. The cycle was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity was reduced to 80% of the maximum discharge capacity) were measured. The results are shown in Table 14 below.

<Vickers Hardness> Further, the obtained hydrogen storage alloys of Examples 109 to 117 and Comparative Example 27 were sliced to a thickness of 8 mm using a micro cutter and mirror-finished with a diamond paste finish of 0.25 μm. Polishing was performed to obtain a sample for evaluation. For each sample, a Vickers hardness tester manufactured by AKASHI Co., Ltd. was applied under the condition of applying a load of 25 gf for 15 seconds.
The hardness was measured, and the results are shown in Table 14 below.

[0434]

[Table 14]

As is clear from Table 14, the secondary batteries of Examples 109 to 117 produced by the casting method and having the composition represented by the general formula (8) were obtained in Comparative Example 27.
It can be seen that the battery has a larger discharge capacity and a longer cycle life as compared with the secondary battery. In addition, the secondary batteries of Examples 109 to 116 each including the negative electrode including a hydrogen storage alloy having a Vickers hardness of less than 700 Hv are similar to the secondary batteries of Example 117 including the negative electrode including a hydrogen storage alloy having a Vickers hardness of 700 Hv or higher. It can be seen that the cycle life is longer than that of the secondary battery.

(Examples 118 to 126) <Evaluation of Electrodes> Nine kinds of alloy ingots were obtained by weighing each element so as to have the composition shown in Table 15 below and melting it in a high frequency induction furnace in an argon atmosphere. Was. Then,
The alloy ingot except for Example 126 was subjected to a heat treatment at 1000 ° C. for 5 hours in an argon atmosphere.

Each of the obtained alloy ingots was made to have a particle size of 75 μm.
The powder was ground as follows to prepare a hydrogen storage alloy powder. The weight ratio of each hydrogen storage alloy powder and electrolytic copper powder is 1:
3, and 1 g of each mixture is 10 tons / cm.
Pellets were produced with a diameter of 10mm by pressed for 5 minutes with a ^second pressure. Each pellet is sandwiched between nickel wire meshes, and the periphery of the wire mesh is spot welded and pressed,
Further, a hydrogen storage electrode (negative electrode) was manufactured by spot welding a nickel lead to the wire mesh.

A test cell was assembled by immersing each of the obtained negative electrodes together with a sintered nickel electrode as a counter electrode in an 8N-KOH aqueous solution (electrolytic solution) in a container.

(Comparative Example 28) A test cell similar to that of Examples 118 to 126 was assembled except that the hydrogen storage alloy powder described below was used.

Each element was weighed so as to have the composition shown in Table 15 below, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Subsequently, these alloy ingots were melted, and the obtained molten metal was heated at 5 m / s in an argon atmosphere.
It was dropped on the surface of a copper single roll rotating at a peripheral speed of ec and rapidly cooled to produce a flake-shaped hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was subjected to a heat treatment at 890 ° C. for 12 hours in an argon atmosphere, and then pulverized to a particle size of 75 μm or less to prepare a hydrogen storage alloy powder.

A charge / discharge cycle test was performed on the test cells of Examples 118 to 126 and Comparative Example 28 at a temperature of 25 ° C. The charge and discharge conditions are as follows: charge at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours, pause for 10 minutes, and then discharge at a current of 50 mA per 1 g of the hydrogen storage alloy to -0.6 V with respect to the mercury oxide electrode. The cycle was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity was reduced to 80% of the maximum discharge capacity) were measured. The results are shown in Table 16 below.

<Vickers Hardness> Further, with respect to the obtained hydrogen storage alloys of Examples 118 to 126 and Comparative Example 28, Vickers hardness was measured in the same manner as described in Examples 109 to 117 described above. Table 16 below
It is described together.

[0443]

[Table 15]

[0444]

[Table 16]

As is apparent from Tables 15 and 16,
The secondary batteries of Examples 118 to 126 produced by the casting method and having the composition represented by the general formula (9) have a larger discharge capacity than the secondary battery of Comparative Example 28, and have a higher cycle capacity. It can be seen that the life is long. In addition, the secondary batteries of Examples 118 to 125 provided with the negative electrode including a hydrogen storage alloy having a Vickers hardness of less than 700 Hv are the secondary batteries of Examples 126 including the negative electrode including a hydrogen storage alloy having a Vickers hardness of 700 Hv or more. It can be seen that the cycle life is longer than that of the secondary battery.

(Examples 127 to 140 and Comparative Examples 29 to 140)
31) Finally, each element was weighed in view of the yield so as to have the composition ratio shown in Table 17, and was melted in a high-frequency melting furnace in an argon atmosphere to produce an alloy ingot. Each of the obtained ingots was subjected to a heat treatment at 1000 ° C. for 5 hours in an argon atmosphere to obtain a hydrogen storage alloy ingot having a composition shown in Table 17 below.

Each of the hydrogen storage alloy ingots is pulverized,
After sieving to a particle size of 75 μm or less, an electrode was prepared according to the procedure described below. First, 5
Add 150 μl of a PVA (polyvinyl alcohol) aqueous solution prepared to a weight%, knead it sufficiently to form a paste, apply it evenly to a 2 cm square foam metal with terminals attached, and dry it sufficiently in air. After that, it was dried in vacuum. Then, press at a pressure of ² t / cm ² ,
An alloy electrode (negative electrode) was produced.

The obtained negative electrode was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and a charge / discharge test was performed at each temperature (25 ° C. and 50 ° C.). The charge and discharge conditions were as follows: at each temperature, the battery was charged at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours,
Then, the battery was discharged at a current of 50 mA per 1 g of the hydrogen storage alloy until the voltage of the reference electrode of mercury oxide became -0.6 V, and the discharge was resumed for 10 minutes. 2
The discharge capacity retention rate (%) at 50 ° C. was measured from the discharge capacities at 5 ° C. and 50 ° C. according to the following formula (i). The results are shown in Table 18 below.

Retention rate (%) = {C (50 ° C.) / C (25 ° C.)} × 100 (i) In the formula (i), C (50 ° C.) is 50 cycles in a charge / discharge test at 50 ° C. Eye discharge capacity, C (25
° C) indicates the discharge capacity at the 50th cycle in the charge / discharge test at 25 ° C.

[0450]

[Table 17]

[0451]

[Table 18]

As is clear from Tables 17 and 18, the secondary batteries of Examples 127 to 140 provided with a negative electrode containing a hydrogen storage alloy having a Ce content of less than 20% by weight in R2 had an R
It can be seen that a decrease in discharge capacity at a high temperature can be suppressed as compared with Comparative Examples 29 to 31 including negative electrodes containing a hydrogen storage alloy having a Ce content of more than 20% by weight in Sample No. 2.

(Examples 141 to 150 and Comparative Examples 32 to
35) Finally, each element was weighed in view of the yield so as to have the composition ratio shown in Table 19, and an alloy ingot was produced by high-frequency melting in an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on a surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to obtain a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was heated at 890 ° C for 1 hour.
Heat treatment for 2 hours was performed under an argon atmosphere.

The obtained flaky hydrogen storage alloy was pulverized,
After sieving to a particle size of 75 μm or less,
A hydrogen storage alloy electrode (negative electrode) was produced in the same manner as described in 27 to 140.

The obtained negative electrode was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and a charge / discharge test was performed at each temperature (25 ° C. and 50 ° C.). The charging / discharging conditions are the same as those in Examples 127 to 14 described above.
0 as described above. The discharge capacity retention rate (%) at 50 ° C. was measured from the discharge capacities at 25 ° C. and 50 ° C. according to the above-mentioned equation (i), and the results were shown in Table 2 below.
0 is shown.

[0456]

[Table 19]

[0457]

[Table 20]

As is clear from Tables 19 to 20, the secondary batteries of Examples 141 to 150 provided with a negative electrode containing a hydrogen storage alloy having a Ce content of less than 20% by weight in R2 have an R
It can be seen that a decrease in discharge capacity at a high temperature can be suppressed as compared with Comparative Examples 32 to 35 each including a negative electrode containing a hydrogen storage alloy having a Ce content of more than 20% by weight in Sample No. 2. Further, the hydrogen storage alloy contained in the negative electrodes of the secondary batteries of Examples 141 to 150 was produced by a quenching method. On the other hand, the hydrogen storage alloy contained in the negative electrodes of Examples 127 to 140 described above is manufactured by a casting method,
The cooling rate is slower than in Examples 141 to 150. As is clear from Tables 16 to 19, the secondary batteries of Examples 141 to 150 have a discharge capacity comparable to the secondary batteries of Examples 127 to 140. Even if a hydrogen storage alloy is produced by rapid solidification such as a roll rapid cooling method as in the secondary batteries of Examples 141 to 150, the discharge capacity retention rate at 50 ° C. is high because the Ce content in R2 is 20% by weight. It is presumed that a hydrogen storage alloy having a small number of surface defects can be obtained by having a composition of less than 10% by quenching.

(Examples 151 to 163, Reference Examples 1 to 4, and Comparative Example 36) Each element was weighed in view of the yield so that the composition ratio finally shown in Table 21 was obtained. An alloy ingot was produced by dissolving the above. Each of the obtained ingots was subjected to a heat treatment at 1000 ° C. for 5 hours in an argon atmosphere to obtain a hydrogen storage alloy ingot having a composition shown in Table 21 below.

Each of the hydrogen storage alloy ingots is pulverized,
After sieving to a particle size of 75 μm or less,
A hydrogen storage alloy electrode (negative electrode) was produced in the same manner as described in 27 to 140.

The obtained negative electrode was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and a charge / discharge test was performed at each temperature (25 ° C. and 50 ° C.). The charging / discharging conditions are the same as those in Examples 127 to 14 described above.
0 as described above. The discharge capacity retention rate (%) at 50 ° C. was measured from the discharge capacities at 25 ° C. and 50 ° C. according to the above-mentioned equation (i), and the results were shown in Table 2 below.
It is shown in FIG. Table 22 shows the above-mentioned formula (I);
Acceptable Ce content m calculated from 125y + 20
(% By weight) and C contained in R3 of the actual hydrogen storage alloy
The e amount (% by weight) is also indicated.

[0462]

[Table 21]

[0463]

[Table 22]

As is clear from Tables 21 to 22, the Ce content in R3 was determined by the value (m) calculated from the above-described formula (I).
(% By weight) of the secondary batteries of Examples 151 to 153 provided with a negative electrode including a hydrogen storage alloy having a smaller amount of hydrogen storage alloy. It can be seen that a decrease in the discharge capacity under a high temperature environment can be suppressed as compared with the secondary battery of No. 1. Also, from the comparison of the characteristics of the secondary batteries of Examples 154 to 156 and Reference Example 2 and the comparison of the characteristics of the secondary batteries of Examples 157 to 159 and Reference Example 3, the same applies when the Co content is changed. It can be seen that there is a tendency. Furthermore, even when the atomic ratio of each element and the type of element are different as in Examples 160 to 163, if the Ce content in R3 is less than m wt%, the discharge capacity at high temperatures decreases. It can be seen that it can be suppressed.

(Examples 164-175 and Comparative Example 37-
43) Finally, each element was weighed in consideration of the yield so that the composition ratio shown in Table 23 was obtained, and an alloy ingot was produced by high-frequency melting in an argon atmosphere. Subsequently, these alloy ingots were melted, and the obtained molten metal was dropped on a surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere and rapidly cooled to obtain a flaky hydrogen storage alloy. Subsequently, each flaky hydrogen storage alloy was heated at 890 ° C for 1 hour.
Heat treatment for 2 hours was performed under an argon atmosphere.

The obtained flaky hydrogen storage alloy was pulverized,
After sieving to a particle size of 75 μm or less,
A hydrogen storage alloy electrode (negative electrode) was produced in the same manner as described in 27 to 140.

The obtained negative electrode was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and a charge / discharge test was performed at each temperature (25 ° C. and 50 ° C.). The charging / discharging conditions are the same as those in Examples 127 to 14 described above.
0 as described above. The discharge capacity retention rate (%) at 50 ° C. was measured from the discharge capacities at 25 ° C. and 50 ° C. according to the above-mentioned equation (i), and the results were shown in Table 2 below.
It is shown in FIG. Table 24 shows the above-mentioned formula (I);
Acceptable Ce content m calculated from 125y + 20
(% By weight) and C contained in R3 of the actual hydrogen storage alloy
The e amount (% by weight) is also indicated.

[0468]

[Table 23]

[0469]

[Table 24]

As is clear from Tables 23 and 24, the Ce content in R3 is determined by the formula (I) described above; m = 125y + 20
The secondary batteries of Examples 164 to 166 each including the negative electrode including a hydrogen storage alloy having a value smaller than the value calculated from (m% by weight) have a Ce content in R3 of more than m% by weight. It can be seen that a decrease in the discharge capacity in a high-temperature environment can be suppressed as compared with the secondary battery of Comparative Example 37 including the negative electrode including the negative electrode. Examples 167 to 169 and Comparative Example 3
Of the secondary battery of Example 8 and Examples 170 to
From comparison of the characteristics of the secondary batteries of Comparative Example 172 and Comparative Example 39, it can be seen that the same tendency is exhibited when the Co content is changed. Further, even when the atomic ratio of each element and the type of element are different as in Examples 173 to 175, if the Ce content in R3 is less than m wt%, the discharge capacity at high temperatures decreases. It can be seen that it can be suppressed.

The hydrogen storage alloy contained in the negative electrodes of the secondary batteries of Examples 164 to 175 was produced by a rapid cooling method. On the other hand, the above-mentioned embodiments 151 to 163
The hydrogen storage alloy contained in the negative electrode was produced by a casting method, and the cooling rate was slower than in Examples 164 to 175. As is clear from Tables 21 to 24,
The secondary batteries of Examples 164 to 175 are described in Example 151.
It can be seen that a discharge capacity comparable to that of the secondary batteries of Nos. 163 to 163 can be obtained. Even when a hydrogen storage alloy is produced by rapid solidification such as a roll rapid cooling method as in the secondary batteries of Examples 164 to 175, the discharge capacity retention rate at 50 ° C. is high because of R3
It is presumed that, by regulating the content of Ce in the above-mentioned formula (I), a hydrogen storage alloy having few plane defects can be obtained even by the quenching method.

(Examples 176 to 195 and Comparative Examples 44 to
45) Each element was weighed so as to have the composition shown in the following Tables 25 and 26, melted in a high-frequency induction furnace in an atmosphere of argon, poured into a water-cooled copper mold, and solidified to produce an alloy ingot. Next, 9
Heat treatment was performed at 00 ° C. for 8 hours under an argon atmosphere.
Each of the obtained alloy ingots was pulverized so as to have a particle size of 150 μm or less to prepare a hydrogen storage alloy powder. The misch metal (Lm) in Tables 25 and 26 is 90 wt%.
La, 2 wt% Ce, 5 wt% Pr and 3 wt%
Of Nd. On the other hand, misch metal (M
m) is 35 wt% La, 50.3 wt% Ce,
5.5 wt% Pr, 9 wt% Nd and 0.2 wt%
Of Sm.

(Comparative Examples 46 to 48)
Was weighed so as to have the composition shown in Table 2, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Then,
These alloy ingots were melted, and the obtained molten metal was dropped and quenched on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere to produce a flaky hydrogen storage alloy. Subsequently, 900 for each flaky hydrogen storage alloy
After heat treatment at 8 ° C. for 8 hours in an argon atmosphere, the powder was pulverized to a particle size of 150 μm or less to prepare a hydrogen storage alloy powder.

With respect to the obtained hydrogen storage alloys of Examples 176 to 195 and Comparative Examples 44 to 48, the following (1) to
The characteristics described in (3) were measured.

(1) For each hydrogen storage alloy, use an EDX analyzer (Energy Dispersive X-ray) of a transmission electron microscope.
Using a Spectrometer), the composition of the main phase was analyzed at a beam diameter of 4 nm, and a and z in the obtained composition formulas are shown in Tables 27 and 28 below. Further, δ at the above-mentioned formula (II); z = −6 × a + δ was calculated from the obtained values of a and z, and the results are shown in Tables 27 and 28 below.

(2) Using a transmission electron microscope, the (1,0,0) plane of the main phase was photographed with a magnification of 20,000 times in 10 visual fields for each hydrogen storage alloy. In addition, the imaging location was different for each visual field. Next, the number of plane defects per 100 nm was measured at any ten locations in each field of view, and the results are shown in Tables 27 and 28 below.

(3) The hydrogen storage properties of each hydrogen storage alloy powder were determined by the Sievertz method (JIS H7201).
The pressure-composition isotherm was measured at 60 ° C. under a hydrogen pressure of less than 10 atm, and the effective hydrogen storage amount (JIS H7003) was measured.
Hydrogen storage alloy term) and the results are shown in Table 29 below.
Also described in 30.

The (1,0,0) plane of the crystal grains constituting the main phase of the hydrogen storage alloy of Example 177 was photographed at a magnification of 20,000 with a transmission electron microscope, and the obtained electron micrograph was taken. As shown in FIG.

Also, Examples 176 to 195 and Comparative Example 4
Hydrogen storage electrodes (negative electrodes) were manufactured from the hydrogen storage alloy powders Nos. 4 to 48 by the method described below. That is, each of the hydrogen storage alloy powder and the electrolytic copper powder were mixed at a weight ratio of 1: 3, and 1 g of each mixture was added at 10 tons / ton.
10 mm in diameter by pressing for 5 minutes at a pressure of cm ²
Was prepared. Each pellet was sandwiched between nickel metal meshes, the periphery of the metal mesh was spot-welded and pressed, and a nickel lead was spot-welded to the metal mesh to produce a hydrogen storage electrode (negative electrode).

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte solution) in a container together with a sintered nickel electrode as a counter electrode, and a charge / discharge cycle test was performed at a temperature of 20 ° C. The charge and discharge conditions were as follows: the battery was charged at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours, paused for 10 minutes, and then with a current of 100 mA per 1 g of the hydrogen storage alloy with respect to the mercury oxide electrode.
The cycle of discharging until the voltage reached 0.7 V was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity decreased to 70% of the maximum discharge capacity) were measured. The results are shown in Tables 29 and 30 below.

[0481]

[Table 25]

[0482]

[Table 26]

[0483]

[Table 27]

[0484]

[Table 28]

[0485]

[Table 29]

[0486]

[Table 30]

As is clear from Tables 25 to 30, the composition has the composition represented by the general formula (12), and a and z in the general formula (12) satisfy the above-mentioned formula (II). Examples 176 to 176 in which the crystal phase of the composition is the main phase, and the number of plane defects in the main phase is 20 or less per 100 nm.
It can be seen that the hydrogen storage alloy of 195 has a higher effective hydrogen storage amount (H / M) than the hydrogen storage alloys of Comparative Examples 44 to 48. In addition, the secondary batteries of Examples 176 to 195 each including a negative electrode including a hydrogen storage alloy in which the crystal phase having such a specific composition is a main phase and the surface defects in the main phase are restricted to the above range are provided. It can be seen that both the discharge capacity and the cycle life are superior to the secondary batteries of Comparative Examples 44 to 48.

(Examples 196-215 and Comparative Examples 49-
50) Each element was weighed so as to have the composition shown in Tables 31 and 32 below, melted in a high-frequency induction furnace in an atmosphere of argon, poured into a water-cooled copper mold, and solidified to prepare an alloy ingot. Next, 8 of these alloy ingots
Heat treatment at 90 ° C. for 12 hours was performed under an argon atmosphere. Each of the obtained alloy ingots was pulverized so as to have a particle size of 125 μm or less to prepare a hydrogen storage alloy powder. The misch metal (Lm) in Tables 31 and 32 is 94
wt% La, 2 wt% Ce, 2 wt% Pr and 2
It is composed of wt% Nd. On the other hand, misch metal (Mm) contains 35 wt% La and 50.3 wt% C
e, 5.5 wt% Pr, 9 wt% Nd and 0.2 w
It consists of t% of Sm.

(Comparative Examples 51 to 53)
Was weighed so as to have the composition shown in Table 2, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Then,
These alloy ingots were melted, and the obtained molten metal was dropped and quenched on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere to produce a flaky hydrogen storage alloy. Next, 890 was added to each flaky hydrogen storage alloy.
C. for 12 hours under argon atmosphere
The powder was pulverized so as to have a particle size of 125 μm or less to prepare a hydrogen storage alloy powder.

With respect to the obtained hydrogen storage alloys of Examples 196 to 215 and Comparative Examples 49 to 53,
The characteristics described in (3) were measured.

(1) The composition of the main phase of each hydrogen-absorbing alloy was analyzed using a transmission electron microscope EDX analyzer at a beam diameter of 4 nm, and a and z in the obtained composition formulas were expressed in Tables 33 and 34 below. Shown in Also, the obtained a and z
Is calculated from the above formula (II); z = −6 × a + δ, and the results are shown in Tables 33 and 34 below.

(2) Using a transmission electron microscope, an arbitrary crystal grain of each hydrogen storage alloy was magnified by a factor of 30,000 at a magnification of 30,000.
Field of view was taken. The crystal grains to be photographed were different for each visual field. Next, the number of plane defects was measured at any ten locations in each field of view (each crystal grain), and 10
The average number of plane defects per 0 nm was calculated, and the results are shown in Tables 33 and 34 below. The area ratio of crystal grains having an average number of plane defects of 20 or less per 100 nm was measured, and the results are shown in Tables 33 and 34 below.

(3) The hydrogen storage properties of each hydrogen storage alloy powder were determined by the Siebelz method (JIS H7201).
The pressure-composition isotherm was measured at 60 ° C. under a hydrogen pressure of less than 10 atm, and the effective hydrogen storage amount (JIS H7003)
Hydrogen storage alloy term), and the results are shown in Table 35 below.
36.

Also, Examples 196 to 215 and Comparative Example 4
Example 176 described above from the hydrogen storage alloy powders of Nos. 9 to 53
To 195, a hydrogen storage electrode (negative electrode) was manufactured in the same manner as described above.

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte solution) in a container together with a sintered nickel electrode as a counter electrode, and a charge / discharge cycle test was performed at a temperature of 20 ° C. The charge and discharge conditions were as follows: the battery was charged at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours, paused for 10 minutes, and then with a current of 150 mA per 1 g of the hydrogen storage alloy with respect to the mercury oxide electrode.
The cycle of discharging until the voltage reached 0.7 V was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity decreased to 70% of the maximum discharge capacity) were measured. The results are shown in Tables 35 and 36 below.

[0496]

[Table 31]

[0497]

[Table 32]

[0498]

[Table 33]

[0499]

[Table 34]

[0500]

[Table 35]

[0501]

[Table 36]

As is clear from Tables 31 to 36, it has the composition represented by the general formula (13), and a and z in the general formula (13) satisfy the aforementioned formula (II). The crystal phase of the composition is the main phase, and the number of plane defects in the crystal grains is 1
The hydrogen storage alloys of Examples 196 to 215 containing more than 70% by volume of a crystal phase of not more than 20 per 00 nm were more effective hydrogen storage amounts (H / M) than the hydrogen storage alloys of Comparative Examples 49 to 53. Is high. Examples 196 to 215 each including a negative electrode containing a hydrogen storage alloy containing a crystal phase having such a specific composition as a main phase and a specific amount of a crystal phase having a surface defect in a crystal grain in the above range are included. The secondary battery of Comparative Example 4 has both the discharge capacity and the cycle life.
It turns out that it is superior to the secondary batteries of Nos. 9 to 53.

(Examples 216 to 235 and Comparative Examples 54 to
55) Each element was weighed so as to have the composition shown in Tables 37 and 38 below, melted in a high-frequency induction furnace in an atmosphere of argon, poured into a water-cooled copper mold, and solidified to prepare an alloy ingot. Next, 8 of these alloy ingots
Heat treatment at 90 ° C. for 12 hours was performed under an argon atmosphere. Each of the obtained alloy ingots was pulverized so as to have a particle diameter of 100 μm or less to prepare a hydrogen storage alloy powder. The misch metal (Lm) in Tables 37 and 38 is 85
It is composed of wt% La, 3 wt% Ce, 10 wt% Pr, and 2 wt% Nd. On the other hand, misch metal (Mm) contains 38 wt% La, 50.3 wt% Ce, 5.5 wt% Pr, 6 wt% Nd and 0.2 wt%.
It consists of wt% of Sm.

(Comparative Examples 56 to 59) Table 38 below shows each element.
Was weighed so as to have the composition shown in Table 2, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Then,
These alloy ingots were melted, and the obtained molten metal was dropped and quenched on the surface of a copper single roll rotating at a peripheral speed of 5 m / sec in an argon atmosphere to produce a flaky hydrogen storage alloy. Next, 890 was added to each flaky hydrogen storage alloy.
C. for 12 hours under argon atmosphere
The powder was pulverized so as to have a particle size of 100 μm or less to prepare a hydrogen storage alloy powder.

With respect to the obtained hydrogen storage alloys of Examples 216 to 235 and Comparative Examples 54 to 59, the following (1) to
The characteristics described in (2) were measured.

(1) For each hydrogen storage alloy, a secondary electron image and a reflected electron image were taken using a scanning electron microscope (SEM), and the composition of each phase was analyzed using an EDX analyzer of the scanning electron microscope. And a and z of the composition of the main phase, Ca
Area ratio of crystal phase having Cu ₅ type crystal structure and MgC
The area ratio of the crystal phase having the u ₂ type crystal structure was measured, and the results are shown in Tables 39 and 40 below. Further, δ at the above-mentioned equation (II); z = −6 × a + δ was calculated from the obtained values of a and z, and the results are shown in Tables 39 and 40 below.

(2) The hydrogen storage properties of each hydrogen storage alloy powder were determined by the Sievertz method (JIS H7201).
The pressure-composition isotherm was measured at 60 ° C. under a hydrogen pressure of less than 10 atm, and the effective hydrogen storage amount (JIS H7003) was measured.
Hydrogen storage alloy term) and the results are shown in Table 41 below.
42.

Also, Examples 216 to 235 and Comparative Example 5
Example 176 described above from the hydrogen storage alloy powders of Nos. 4 to 59
To 195, a hydrogen storage electrode (negative electrode) was manufactured in the same manner as described above.

Each of the obtained negative electrodes was immersed in an 8N-KOH aqueous solution (electrolyte solution) in a container together with a sintered nickel electrode as a counter electrode, and a charge / discharge cycle test was performed at a temperature of 20 ° C. The charge and discharge conditions were as follows: the battery was charged at a current of 100 mA per 1 g of the hydrogen storage alloy for 5 hours, paused for 10 minutes, and then with a current of 200 mA per 1 g of the hydrogen storage alloy with respect to the mercury oxide electrode.
The cycle of discharging until the voltage reached 0.7 V was repeated, and the maximum discharge capacity and the cycle life (the number of cycles when the discharge capacity decreased to 70% of the maximum discharge capacity) were measured. The results are shown in Tables 41 and 42 below.

[0510]

[Table 37]

[0511]

[Table 38]

[0512]

[Table 39]

[0513]

[Table 40]

[0514]

[Table 41]

[0515]

[Table 42]

As is clear from the above Tables 37 to 42, it has the composition represented by the aforementioned general formula (14), and a and z in the aforementioned general formula (14) satisfy the aforementioned formula (II). Example 216 in which a crystal phase is a main phase, a crystal phase having a CaCu ₅ type crystal structure is 20% by volume or less, and a crystal phase having a MgCu ₂ type crystal structure is 10% by volume or less.
It can be understood that the hydrogen storage alloys Nos. 235 to 235 have higher effective hydrogen storage amounts (H / M) than the hydrogen storage alloys of Comparative Examples 54 to 59. Example 21 including the negative electrode containing the hydrogen storage alloy having the specific crystal phase in which the content ratio of the specific crystal phase was a specific amount was used.
It can be seen that the secondary batteries of Nos. 6 to 235 are superior in both the discharge capacity and the cycle life to the secondary batteries of Comparative Examples 54 to 59.

(Examples 236 to 249 and Comparative Example 60)
61) Each element was weighed so as to have the composition shown in Tables 43 and 44 below and melted in a high-frequency induction furnace under an argon atmosphere to produce an alloy ingot. These alloy ingots were subjected to a heat treatment at 970 ° C. for 6 hours in an argon atmosphere. In Tables 43 and 44, Lm is La = 94 at%, Ce = 2 at%, Pr = 1 at%, Nd = 3 at%.
Mm is La = 35 at%, Ce = 5
0.3 at%, Pr = 5.5 at%, Nd = 9 at%,
It has a composition of Sm = 0.2 atomic%.

With respect to each of the obtained hydrogen storage alloys, characteristics described in the following (a) to (c) were measured.

(A) For each hydrogen storage alloy powder, Cu
The crystal structure of the main phase was determined by observing the crystal structure from an X-ray diffraction pattern using -Kα radiation as an X-ray source.

(B) For each hydrogen storage alloy, the area ratio of the main phase was measured using a scanning electron microscope (SEM).
The area ratio was obtained by averaging the area ratio of the main phase to the entire alloy in the field of view using SEM photographs of five visual fields.

(C) The hydrogen storage properties of each hydrogen storage alloy powder were determined by the Sievertz method (JIS H7201).
, A pressure-composition isotherm was measured at 60 ° C. under a hydrogen pressure of less than 10 atm, and the effective hydrogen storage amount (JIS H700
3 Hydrogen storage alloy terminology).

The results are shown in Tables 43 and 44 below.

The obtained alloy ingot was pulverized to a size of 150 μm or less to produce 14 kinds of hydrogen storage alloy powders. The hydrogen storage alloy powder and the electrolytic copper powder were mixed at a weight ratio of 1: 2, and 1 g of the mixture was pressed at a pressure of 10,000 kg / cm ² for 5 minutes to obtain a 12 mm diameter. Was prepared. These pellets were sandwiched between nickel metal meshes, the peripheral portions were spot-welded and pressed, and the nickel lead wires were spot-welded to produce 14 kinds of hydrogen storage alloy electrodes (negative electrodes).

Next, each of the negative electrodes was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode to assemble cells.

The obtained cells were subjected to a charge / discharge cycle test at a temperature of 20 ° C. The charge and discharge conditions were as follows: after charging for 5 hours at a current of 100 mA per 1 g of hydrogen storage alloy, resting for 10 minutes, and then charging for 100 m per 1 g of hydrogen storage alloy.
Repeat the cycle of discharging with the current of A to -0.6 V with respect to the mercury oxide electrode, and measure the maximum discharge capacity and cycle life (the number of cycles when the discharge capacity decreases to 80% of the maximum discharge capacity). did. The results are shown in Table 4 below.
3, shown in Table 44.

[0526]

[Table 43]

[0527]

[Table 44]

[0528] As is apparent from Table 43 and Table 44, represented by _{R1 1-ab Mg a T2 b} (Ni 1-x M7 x) z, main phase Ce ₂ Ni ₇ type, CeNi ₃ type, Gd ₂ C
The metal oxides of Examples 236 to 249 each including a negative electrode containing a hydrogen storage alloy, which is at least one phase selected from phases having any one of o ₇ type and PuNi ₃ type crystal structures.
The hydrogen secondary battery was a secondary battery of Comparative Example 60 including a negative electrode having a main phase containing an AB ₅ type hydrogen storage alloy such as a CaCu ₅ type and an AB ₂ type hydrogen such as a MgCu ₂ type as a main phase. Since the effective hydrogen storage amount of the hydrogen storage alloy in the negative electrode is larger than that of the secondary battery of Comparative Example 61 including the negative electrode including the storage alloy, it can be seen that both the discharge capacity and the cycle life are excellent.

(Examples 250 to 270 and Comparative Example 62)
-66) A hydrogen storage alloy ingot or a flake-shaped hydrogen storage alloy was obtained by high-frequency induction melting or molten metal quenching described below.

(High Frequency Induction Melting) Each element was weighed so as to have the compositions shown in Tables 45 and 47 below, and melted in a high frequency induction furnace in an argon atmosphere to produce a hydrogen storage alloy ingot.

(Molten metal quenching method) Each element is shown in Tables 45 and 47 below.
Was weighed so as to have the composition shown in Table 2, and an alloy ingot was produced by high frequency melting under an atmosphere of argon. Then,
These alloy ingots were melted, and the obtained molten metal was dropped on a surface of a copper single roll rotating at a peripheral speed of 15 m / sec in an argon atmosphere and rapidly cooled to produce a flake-shaped hydrogen storage alloy.

Each of the obtained hydrogen storage alloy ingots and each hydrogen storage alloy flake was subjected to the following Table 46 in an Ar atmosphere.
The heat treatment was performed under the conditions (temperature and time) shown in Table 48. In Tables 45 and 47, Lm is La = 94 at%, Ce = 2 at%, Pr = 1 at%, Nd = 3 at%.
Mm is La = 35 at%, Ce = 5
0.3 at%, Pr = 5.5 at%, Nd = 9 at%,
It has a composition of Sm = 0.2 atomic%.

The characteristics described in (a) and (b) above were measured for each of the obtained hydrogen storage alloys, and the results are shown in Tables 45 and 47 below.

Each of the obtained ingots and flakes was mechanically pulverized and sieved to give 20 μm to 15 μm.
A 0 μm hydrogen storage alloy powder was produced. The hydrogen storage alloy powder and the electrolytic copper powder were mixed at a weight ratio of 1: 3, and 1 g of the mixture was mixed at a pressure of 1000 kg / cm ^{2 with} a pressure of 5 kg.
By pressing for minutes, pellets having a diameter of 12 mm were produced. 26 kinds of hydrogen storage alloy electrodes (negative electrodes) were produced by sandwiching these pellets with a nickel metal mesh, spot-welding the peripheral portion by pressure welding, and spot-welding a nickel lead wire.

Next, each of the negative electrodes was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode to assemble a cell.

The obtained cells were subjected to a charge / discharge cycle test at 25 ° C. 1 per g of hydrogen storage alloy
After charging for 5 hours with a current of 00 mA, rest for 10 minutes,
A cycle of discharging at a current of 50 mA per 1 g of the hydrogen storage alloy to the mercury oxide electrode until -0.6 V was repeated, and the maximum discharge capacity was measured. Further, the potential at the discharge midpoint in the third cycle was measured. Further, the cycle life was measured. The results are shown in Tables 46 and 48.

[0537]

[Table 45]

[0538]

[Table 46]

[0539]

[Table 47]

[0540]

[Table 48]

As is clear from Tables 45 to 48,
_{R1 1-ab Mg a T2 b} (Ni 1-x M7 x) is represented by _z, and main phase Ce ₂ Ni ₇ type or, alternatively PuNi ₃
The metal oxide-hydrogen secondary batteries of Examples 250 to 270 each including a negative electrode including a hydrogen storage alloy having a
It can be seen that the secondary batteries of Comparative Examples 62 to 66 exhibit superior discharge capacity and cycle life.

(Examples 271 to 288 and Comparative Examples 67 to
72) Example 21 was prepared by weighing each element so as to have a predetermined composition ratio and performing high frequency melting in an argon atmosphere.
Hydrogen storage alloy ingots of Nos. 7 to 278 and Comparative Examples 67 to 69 were obtained. In addition, RNi ₅ series having a relatively high melting point, R ₂
Ni ₇ -based, RNi ₃ -based, RNi ₂ -based and MgNi-based alloys were prepared by a high frequency melting method, and then mixed in a predetermined amount and further melted to obtain hydrogen absorbing alloys of Examples 279 to 288 and Comparative Examples 70 to 72. Was prepared.

Among the obtained alloys, Comparative Examples 69, 70,
Reference numeral 72 denotes only casting, and all of Comparative Examples 67, 68, 71 and Examples were heat-treated at 900 ° C. for 7 hours,
After heat treatment for 0 hour, the powder was pulverized to prepare an alloy powder having a particle size of 125 μm or less.

<Evaluation of Hydrogen Storage Rate> Each of the above hydrogen storage alloys was used for the sample container 33 shown in FIG.
Housed inside. Closing the first valve 37 _1, No. 2, opens the third valve 37 _2, 37 _3, and operating the vacuum pump 35 exhausts the air in the pipe 32 and the branch pipe 34, the pressure accumulator 38 and the sample container 33 did. After closing the second and third valves 37 ₂ and 37 ₃ , the first valve 37 ₁ is opened to supply hydrogen from the hydrogen cylinder 31 and supply the hydrogen to the pipe 32.
And branch pipe 34, pressure accumulator 38 and sample container 33
Was replaced with hydrogen. Subsequently, closing the first valve 37 ₁ was calculated amount of hydrogen was introduced from the pressure in the system indicated by the pressure gauge 36 at this time. Subsequently, the second opening the valve 37 _2, hydrogen was supplied into the sample container 3, and monitor the temperature at the thermocouple 40. Thereafter, the computer 41 and the temperature controller 42 controlled the temperature in the sample container 33 to increase at a constant rate, and the temperature was scanned using the heater 39 receiving the control signal. At this time, the pressure change in the container 33 was detected by the pressure gauge 36 and recorded by the recorder 43.

As described above, a fixed amount of hydrogen was introduced into the sample container 33 at a temperature of 80 ° C., and the amount of hydrogen occluded in each hydrogen storage alloy up to 5 hours after the start of the introduction was measured. The hydrogen storage rate was measured by detecting the change in the internal pressure and calculating the hydrogen storage amount per hour (H / M · h ⁻¹ ). The results are shown in Tables 49 and 50 below.

Tables 49 and 50 below show the composition of each hydrogen storage alloy, the intensity (I ₁ ) of the strongest peak appearing in the range of 2θ = 8 to 13 ° in the X-ray diffraction pattern using CuKα ray, also shown the intensity of the strongest line peak of (I ₂₎ and the intensity ratio of (I ₁ / I _2).

<Evaluation of Secondary Battery with Negative Electrode Containing Hydrogen Storage Alloy> The powder obtained by pulverizing each of the above hydrogen storage alloys to 75 μm or less and electrolytic copper powder were mixed at a weight ratio of 1: 1.
1 g of this mixture was pressed for 5 minutes at a pressure of 10,000 kg using a tableting machine (inner diameter 10 mm) to produce pellets. The pellets were sandwiched between nickel nets, the periphery was spot-welded, and nickel lead wires were spot-welded to produce 24 kinds of alloy electrodes (negative electrodes).

Each of the negative electrodes was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and subjected to a charge / discharge cycle test at a temperature of 25 ° C.
The maximum discharge capacity was measured. The charge and discharge conditions were as follows: after charging for 10 hours at a current of 100 mA per 1 g of hydrogen storage alloy, resting for 10 minutes, and then charging at 20 mA per 1 g of hydrogen storage alloy.
The discharge cycle was repeated until the current reached −0.5 V with respect to the mercury oxide electrode. The maximum discharge capacity during such a charge / discharge cycle was examined. In addition, the cycle life was measured. The results are shown in Tables 49 and 50 below.

[0549]

[Table 49]

[0550]

[Table 50]

As is clear from Tables 49 and 50, the intensity (I ₁ ) of the strongest peak expressed by the general formula (16) and appearing in the range of 2θ = 8 to 13 ° and the strongest line peak of all peaks And the intensity ratio (I ₁ / I ₂ ) to the intensity (I ₂ ) of the sample is 0.
It can be seen that the hydrogen storage alloys of Examples 271 to 288 having a value of less than 15 have better hydrogen storage properties than the hydrogen storage alloys of Comparative Examples 67 to 72. In addition, it can be seen that substitution with a dissimilar metal exhibits more excellent hydrogen storage characteristics.

Also, the batteries of Examples 271 to 288 provided with the negative electrode containing the above-mentioned hydrogen storage alloy have significantly higher discharge capacities and better charge / discharge characteristics than the batteries of Comparative Examples 67 to 72. Recognize.

(Examples 289 to 295 and Comparative Examples 73 to
77) In consideration of the yield so that each element finally has the composition ratio shown in Table 51, the mother alloys LaNi ₅ and LaN
i ₂ , MgNi ₂ , LaNi ₃ Co ₂ , LaNi ₄ M (M =
(Cr, Mn, Cu, Fe, Zn, Sn, Si, P, B)
Was weighed and melted in a high-frequency melting furnace in an argon atmosphere to prepare an alloy ingot. Each of the obtained ingots was heat-treated at 950 ° C. for 5 hours to obtain a hydrogen storage alloy ingot having a composition shown in Table 51 below.

In order to clarify the crystal structure of the obtained hydrogen storage alloy, a sample was prepared by cutting the hydrogen storage alloy ingot in an arbitrary direction and a sample was prepared by cutting the hydrogen storage alloy ingot perpendicularly to the cut surface. 10 samples were arbitrarily selected for each sample, and an electron diffraction image and a lattice image were measured by a TEM.

[0555] As a result, hydrogen absorbing alloys of Examples 289 to 295 are the AB ₅ subcell is C, the A ₂ B ₄ subcells in a pattern (the n 1) n [LCLCC] upon the L represented by AB ₅ subcell and a ₂ B ₄ subcell was confirmed to contain the crystalline phase consisting of stacked unit cells. A ₂ B for the number of AB ₅ subcells in the unit cell
The ratio X (L / C) of the number of _four subcells was 0.67.

FIG. 5 shows that La ₁₀ Mg ₄ Ni of Example 289
16 shows a micrograph of a lattice image observed at the most measurement points in the hydrogen storage alloy having a composition represented by ₄₆ . FIG. 6 is a characteristic diagram for explaining a lattice image of the micrograph of FIG. As apparent from the illustration of FIG. 6, white portions in the photograph of Figure 5 C, i.e. shows the AB ₅ subcells, the black portion denotes L, i.e. the A ₂ B ₄ subcells. From FIG. 5, the hydrogen storage alloy of Example 289 is the same as that of [LCLCC] described above.
It can be seen that it includes a crystal phase composed of unit cells having a lamination pattern represented by.

On the other hand, the hydrogen storage alloys of Comparative Examples 73 to 77 do not have the same crystal phase as that described in Examples 289 to 295 from the results of the observation of the electron diffraction image and the lattice image by the TEM described above. It was confirmed. Further, the hydrogen storage alloys of Comparative Examples 73 and 74 each contained a crystal phase composed of unit cells in which AB ₅ and A ₂ B ₄ subcells were stacked in a pattern represented by [LC]. The ratio X (L / C) of the number of A ₂ B ₄ subcells to the number of AB ₅ subcells in the unit cell was 1.0. Comparative Example 75
The hydrogen storage alloy of A has a pattern represented by [LCC]
B ₅ subcell and A ₂ B ₄ subcell contained the crystalline phase consisting of stacked unit cells. The ratio X of the number of A ₂ B ₄ subcells to the number of AB ₅ subcells in the unit cell
(L / C) was 0.5. In Table 51, Example 289 was added.
295 and the ratio X (L / C) of the number of A ₂ B ₄ subcells to the number of AB ₅ subcells in the unit cells of the alloys of Comparative Examples 73 to 75.

Further, with respect to the hydrogen storage alloys of Examples 289 to 295, the measurement points at which the unit cell having the laminated pattern represented by n [LCLCC] (n is 1) were counted, and the measurement points of the lattice image were measured. The measurement rate of the unit cell was calculated from the number of measurement points where the unit cell was observed when the total number (20 places) was set to 1, and the result was shown in Table 51 below.
It is described together.

<Evaluation of hydrogen storage rate> Each of the above-mentioned hydrogen storage alloys was used for the sample container 33 shown in FIG. 3 (atmospheric temperature 25 ° C.).
Housed inside. Closing the first valve 37 _1, No. 2, opens the third valve 37 _2, 37 _3, and operating the vacuum pump 35 exhausts the air in the pipe 32 and the branch pipe 34, the pressure accumulator 38 and the sample container 33 did. After closing the second and third valves 37 ₂ and 37 ₃ , the first valve 37 ₁ is opened to supply hydrogen from the hydrogen cylinder 31 and supply the hydrogen to the pipe 32.
And branch pipe 34, pressure accumulator 38 and sample container 33
Was replaced with hydrogen. Subsequently, closing the first valve 37 ₁ was calculated amount of hydrogen was introduced from the pressure in the system indicated by the pressure gauge 36 at this time. Subsequently, the second opening the valve 37 _2, hydrogen was supplied into the sample container 3, and monitor the temperature at the thermocouple 40. Thereafter, the computer 41 and the temperature controller 42 controlled the temperature in the sample container 33 to increase at a constant rate, and the temperature was scanned using the heater 39 receiving the control signal. At this time, the pressure change in the container 33 was detected by the pressure gauge 36 and recorded by the recorder 43.

As described above, a fixed amount of hydrogen was introduced into the sample container 33 at a temperature of 60 ° C., and the amount of hydrogen occluded in each hydrogen storage alloy up to 5 hours after the start of introduction was measured. The hydrogen storage rate was measured by detecting the change in the internal pressure and calculating the hydrogen storage amount per hour (H / M · h ⁻¹ ). The results are shown in Table 52 below.

Examples 289 to 295 and Comparative Example 7
After crushing the hydrogen storage alloys No. 3 to No. 77 and sieving the particles to a particle diameter of 75 μm or less, an electrode was produced according to the procedure described below. First, each alloy powder and electrolytic copper powder were mixed at a weight ratio of 1: 1.
mm) for 3 minutes at a pressure of 5 tons to produce pellets. An alloy electrode (negative electrode) was produced by sandwiching the pellets with a nickel wire net, spot-welding the periphery and press-welding, and spot-welding a nickel lead wire.

The obtained negative electrode was immersed in an 8 N aqueous potassium hydroxide solution together with a sintered nickel electrode as a counter electrode, and a charge / discharge test was performed. The charge / discharge test was conducted at 20 ° C. at 100 mA / g of hydrogen storage alloy.
And then cooled to 0 ° C., −18 ° C. or −23 ° C. during a 5-hour rest, and then charged at −100 with respect to the mercury oxide electrode at a current of 100 mA per 1 g of the hydrogen storage alloy. The discharge was performed until the voltage reached 0.6V. Each temperature when the discharge capacity at 0 ° C is 1 (-
18 ° C., −23 ° C.) at −18 ° C. and −
The capacity reduction rate at 23 ° C. was defined as
It is described together.

[0563]

[Table 51]

[0564]

[Table 52]

As is apparent from Tables 51 and 52, the hydrogen storage alloys of Examples 289 to 295 have a higher hydrogen storage rate than the secondary batteries of Comparative Examples 73 to 77.
In addition, the secondary batteries of Examples 289 to 295 were manufactured in Comparative Example 73.
It can be seen that the rate of decrease in capacity at low temperatures is smaller than that of the secondary batteries of Nos. To 77.

[0566]

As described above in detail, according to the hydrogen storage alloy of the present invention, while maintaining a high hydrogen storage capacity, the hydrogen storage alloy has a higher release characteristic than conventional Mg-based hydrogen storage alloys and rare earth-based hydrogen storage alloys. A remarkable effect such as remarkable improvement can be obtained. Therefore, the hydrogen storage alloy of the present invention can be used in various application fields in which other alloy systems have been used so far, such as storage and transport of hydrogen, storage and transport of heat, thermo-mechanical energy conversion, separation and purification of hydrogen, and hydrogen isotope. It has remarkable effects such as the separation of the body, the battery using hydrogen as an active material, the catalyst in synthetic chemistry, the temperature sensor, and the like, and the development of a new field of utilizing a hydrogen storage alloy can be achieved.

According to the secondary battery of the present invention,
A remarkable effect is achieved, such as a high capacity and a long life.

According to the present invention, the A site is changed to AB ₃
A hydrogen storage alloy that has a large hydrogen storage capacity in a composition containing a larger amount than the composition and has improved hydrogen storage and desorption characteristics that has improved the problem that hydrogen stability is too high and hydrogen is hardly released. In addition, a secondary battery having a negative electrode containing the hydrogen storage alloy, a high capacity, excellent charge / discharge cycle characteristics, low cost and light weight can be provided.

Further, according to the present invention, it is possible to provide a hydrogen storage alloy having an improved hydrogen storage rate near ordinary temperature as compared with a conventional magnesium-rare earth hydrogen storage alloy while maintaining a high hydrogen storage capacity. Therefore, the hydrogen storage alloy of the present invention is used in various application fields (storage and transport of hydrogen, storage and transport of heat, thermo-mechanical energy conversion, separation and purification of hydrogen, hydrogen isotope) in which other alloy systems have been used. Separation, a battery using hydrogen as an active material, a catalyst in synthetic chemistry, a temperature sensor, etc.) are further expanded, and further, a remarkable effect is exhibited such that a new field of utilizing a hydrogen storage alloy can be developed.

Further, the secondary battery according to the present invention has high capacity and excellent charge / discharge cycle characteristics by enabling application of the magnesium-containing hydrogen storage alloy to the charge / discharge reaction, which has been conventionally difficult. And so on.

[Brief description of the drawings]

FIG. 1 shows C in R3 in a hydrogen storage alloy according to the present invention.
FIG. 4 is a characteristic diagram showing a relationship between an e content and a Co amount (y).

FIG. 2 is a partially cutaway perspective view showing a cylindrical metal oxide / hydrogen secondary battery as an example of the secondary battery according to the present invention.

FIG. 3 is a schematic diagram showing a temperature scanning type hydrogen storage / release characteristic evaluation apparatus used in an embodiment of the present invention.

FIG. 4 is a micrograph showing a transmission electron microscope image of a main phase of the hydrogen storage alloy of Example 177.

FIG. 5 is a transmission electron micrograph showing a lattice image of the hydrogen storage alloy of Example 289.

FIG. 6 is a characteristic diagram for explaining the micrograph of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... container, 2 ... positive electrode, 4 ... negative electrode, 5 ... electrode group, 7 ... sealing plate, 31 ... hydrogen cylinder, 33 ... sample container, 35 ... vacuum pump, 36 ... pressure gauge, 39 ... heater, 41 ... computer, 42 ... temperature controller.

 ──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. 9-344266 (32) Priority date Heisei 9 (1997) November 28 (33) Priority claim country Japan (JP) (31) Priority Claim No. Hei 9-344436 (32) Priority date Hei 9 (1997) November 28 (33) Priority claiming country Japan (JP) (31) Priority claim number Patent application Hei 10-2994 (32) Priority Japan 10 (1998) March 9 (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-65349 (32) Priority day March 10 (1998) March 16 (33) ) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-70564 (32) Priority date Hei 10 (1998) March 19 (33) Priority claiming country Japan (JP) (72) Inventor Motoi Kanda 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Kawasaki Plant (72) Inventor Hideki Yoshida 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Kawasaki Plant (72) Inventor Fumiyuki Kawashima 1 at Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Research & Development Center (72) Inventor Takao Sawa Komukai, Sai-ku, Kawasaki-shi, Kanagawa No. 1, Toshiba-cho, Toshiba R & D Center (72) Inventor Takamichi Inaba 72, Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture In-house Toshiba Kawasaki Office (72) Inventor Shusuke Inada, Horikawa, Sai-ku, Kawasaki-shi, Kanagawa 72, Tochiba, Kawasaki, Toshiba Corporation (72) Inventor Hirotaka Hayashida 72, Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Hiroshi Kitayama 72, Horikawa-cho, Sakai-ku, Kawasaki, Kanagawa, Japan Address Toshiba Kawasaki Office (72) Inventor Shiro Takeno 8 Shinsugitacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Yokohama Office

Claims (27)

[Claims] An alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (1), or a hydrogen storage alloy containing a crushed product of the alloy ingot. . (Mg _1-ab R1 _a M1 _b ) Ni _z (1) where R1 is at least one element selected from rare earth elements including Y, and M1 is an element having a higher electronegativity than Mg (provided that R1 is , Cr, Mn, Fe,
At least one element selected from the group consisting of Co, Cu, Zn and Ni), a, b and z are each 0.1 ≦ a ≦
0.8, 0 <b ≦ 0.9, 1−ab> 0, 3 ≦ z ≦
Defined as 3.8. 2. A hydrogen storage alloy produced by a casting method or a sintering method and having a composition represented by the following general formula (2) or a pulverized product of the alloy ingot: . Mg _1-a R1 _a (Ni _1-x M2 _x ) _z (2) where R1 is at least one element selected from rare earth elements including Y, and M2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, a, x
And z are respectively 0.1 ≦ a ≦ 0.8 and 0 <x ≦ 0.
9, 3 ≦ z ≦ 3.8. 3. A hydrogen storage alloy produced by a casting method or a sintering method and containing a pulverized product of an alloy ingot having a composition represented by the following general formula (3): . Mg _{1 -ab} R _{1 a} M _{1 b} (Ni _{1 -x} M 2 _x ) _z (3) where R 1 is at least one element selected from rare earth elements including Y, and M 2 is Cr, Mn, Fe, Co, C
at least one element selected from u and Zn, M1 is an element having a higher electronegativity than Mg (provided that the R1
, A, b, x, and z are at least 0.1 ≦ a ≦ 0.8, 0 <b ≦ 0.9, 1-a -B>
0, 0 <x ≦ 0.9 and 3 ≦ z ≦ 3.8. 4. The method according to claim 1, wherein M1 is Al, Ta, V, Nb, G
a, In, Ge, Pb, Mo, Sn, Si, Re, A
g, B, C, P, Ir, Rh, Ru, Os, Pt, A
4. The hydrogen storage alloy according to claim 1, wherein the hydrogen storage alloy is at least one element selected from u, Se, and S. 5. 5. An alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (4), or a hydrogen storage alloy containing a crushed product of the alloy ingot. . Mg _1-a R1 _a (Ni _1-x M3 _x ) _z (4) where R1 is at least one element selected from rare earth elements including Y, and M3 is Co, Mn, Fe, Al, G
a, at least one element selected from Zn, Sn, Cu, Si and B, wherein a, x and z are each 0.6
It is defined as 5 ≦ a ≦ 0.8, 0 <x ≦ 0.6, and 3 ≦ z ≦ 3.8. 6. A hydrogen storage alloy produced by a casting method or a sintering method and having a composition represented by the following general formula (5) or containing a crushed product of the alloy ingot. . Mg _{1 -ab} R _{1 a} T 1 _b (Ni _{1 -x} M 3 _x ) _z (5) wherein R 1 is at least one element selected from rare earth elements including Y, and T 1 is selected from Ca, Ti, Zr and Hf. At least one element, M3 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si and B are at least one element selected from the group consisting of a, b, x, and z of 0.65 ≦ a <0.8 and 0 <b ≦ 0, respectively. .3,
0.65 <(a + b) ≦ 0.8, 0 <x ≦ 0.6, 3 ≦
It is defined as z ≦ 3.8. 7. A hydrogen storage alloy produced by a casting method or a sintering method and containing a pulverized product of an alloy ingot having a composition represented by the following general formula (6) or a crushed product of the alloy ingot. . _{Mg a R1 1-a (Ni} 1-xy Co x M4 y) z (6) however, R1, at least one element selected from rare earth elements including Y, M4 is Mn, Fe, V, Cr, N
b, at least one element selected from Al, Ga, Zn, Sn, Cu, Si, P and B, wherein a, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0 <x ≦ 0.
5, 0 ≦ y ≦ 0.2, 3 ≦ z ≦ 3.8. 8. An alloy ingot produced by a casting method or a sintering method and having a composition represented by the following general formula (7), or a hydrogen storage alloy containing a crushed product of the alloy ingot. . _{Mg a R1 1-ab T2 b} (Ni 1-xy Co x M4 y) z (7) wherein at least one element R1 is selected from rare earth elements including Y, T2 is selected from Ca, Ti and Zr At least one element, M4 is Mn, Fe, V, C
r, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B are at least one element selected from the group consisting of a,
b, x, y and z are respectively 0.2 ≦ a ≦ 0.35, 0
<B ≦ 0.3, 0 <x ≦ 0.5, 0 ≦ y ≦ 0.2, 3 ≦
It is defined as z ≦ 3.8. 9. A hydrogen storage alloy produced by a casting method or a sintering method and having a composition represented by the following general formula (8) or a pulverized product of the alloy ingot: . Mg _a (La _1−b R1 _b ) _1−a Ni _z (8) where R1 is at least one element selected from rare earth elements including Y, and a, b and z are not La but a 0.2 ≦ a ≦ 0.35, 0.01 ≦ b <
0.5, 3 ≦ z ≦ 3.8. 10. It is produced by a casting method or a sintering method,
A hydrogen storage alloy comprising an alloy ingot having a composition represented by the following general formula (9) or a crushed product of the alloy ingot. Mg _a (La _1−b R1 _b ) _1−a (Ni _1−x M3 _x ) _z (9) where R1 is at least one element selected from rare earth elements including Y, and is not La. , M3 is C
o, Mn, Fe, Al, Ga, Zn, Sn, Cu, Si
And at least one element selected from B and a,
b, x and z are 0.2 ≦ a ≦ 0.35 and 0.0, respectively.
1 ≦ b <0.5, 0.1 ≦ x ≦ 0.6, 3 ≦ z ≦ 3.8
Is defined as 11. The hydrogen storage alloy according to claim 9, wherein the alloy ingot has a Vickers hardness of less than 700 Hv (kgf / mm ² ). 12. A hydrogen storage alloy comprising an alloy having a composition represented by the following general formula (10). Mg _a R 2 _1-ab T1 _b (Ni _1-x M 3 _x ) _z (10) where R 2 is at least two elements selected from rare earth elements including Y, and the Ce content of R 2 is 20 wt. %
T1 is at least one element selected from Ca, Ti, Zr and Hf, and M3 is Mn, Fe, C
at least one element selected from the group consisting of o, Al, Ga, Zn, Sn, Cu, Si and B, a, b, x and z
Are respectively 0 <a ≦ 0.5, 0 ≦ b ≦ 0.3, 0 ≦ x
≦ 0.9 and 3 ≦ z <4. 13. The hydrogen storage alloy according to claim 12, wherein one of the rare earth elements constituting the R2 is La, and the La content of the R2 exceeds 70% by weight. 14. A hydrogen storage alloy comprising an alloy having a composition represented by the following general formula (11). Mg _a R 3 _1-ab T1 _b (Ni _1-xy M5 _x Co _y ) _z (11) where R3 is at least two elements selected from rare earth elements containing Y, and the Ce content of R3 is When m is less than m wt%, m is represented by m = 125y + 20 (y is the amount of Co in the formula (11)), and T1 is at least one element selected from Ca, Ti, Zr and Hf; M5
Is at least one element selected from Mn, Fe, Al, Ga, Zn, Sn, Cu, Si and B;
b, x, y and z are respectively 0 <a ≦ 0.5, 0 ≦ b
≦ 0.3, 0 ≦ x ≦ 0.9, 0 <y ≦ 0.4, x + y ≦
0.9, 3 ≦ z <4. 15. A composition represented by the following general formula (12), wherein a and z in the general formula (12) are z = −6.
× a + δ (δ is 5−0.2 ≦ δ ≦ 5 + 0.2)
And a plane defect in the main phase is 1%.
A hydrogen storage alloy comprising 20 or less alloys per 00 nm. _{Mg a R1 1-ab T1 b} (Ni 1-x M6 x) z (12) however, R1, at least one element selected from rare earth elements including Y, T1 is selected Ca, Ti, from Zr and Hf At least one element, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8. 16. The hydrogen storage alloy according to claim 15, wherein the number of plane defects in the main phase is 10 or less per 100 nm. 17. A composition represented by the following general formula (13), wherein a and z in the general formula (13) are z = −6.
× a + δ (δ is 5−0.2 ≦ δ ≦ 5 + 0.2)
A hydrogen storage alloy comprising an alloy containing, as a main phase, a phase satisfying the following condition, and containing more than 70% by volume of crystal grains having 20 or less plane defects per 100 nm. _{Mg a R1 1-ab T1 b} (Ni 1-x M6 x) z (13) however, R1, at least one element selected from rare earth elements including Y, T1 is selected Ca, Ti, from Zr and Hf At least one element, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8. 18. A plane defect in the crystal grain is 100 nm.
18. The hydrogen storage alloy according to claim 17, wherein the number of the hydrogen storage alloys is 10 or less. 19. It has a composition represented by the following general formula (14), wherein a and z in the general formula (14) are z = −6.
× a + δ (δ is 5−0.2 ≦ δ ≦ 5 + 0.2)
Characterized by containing an alloy in which a phase satisfying the following condition is a main phase, a crystal phase having a CaCu ₅ type crystal structure is 20% by volume or less, and a crystal phase having a MgCu ₂ type crystal structure is 10% by volume or less. Hydrogen storage alloy. _{Mg a R1 1-ab T1 b} (Ni 1-x M6 x) z (14) however, R1, at least one element selected from rare earth elements including Y, T1 is selected Ca, Ti, from Zr and Hf At least one element, M6 is Co, Mn,
Fe, Al, Ga, Zn, Sn, Cu, Si, B, N
b, W, Mo, V, Cr, Ta, P, and S are at least one element selected from the group consisting of a, b, x, and z, each of 0.2 ≦ a ≦ 0.35 and 0 ≦ b ≦ 0. 0.3, 0 <x ≦
0.6, 3 ≦ z ≦ 3.8. 20. The R1 is composed of two or more kinds of rare earth elements including Ce, and the content of Ce in the R1 is 20% by weight.
18. The method of claim 15, 17 or 1
9. The hydrogen storage alloy according to any one of 9 above. 21. A compound represented by the following general formula (15), wherein the main phase is Ce ₂ Ni ₇ type, CeNi ₃ type, Gd ₂ Co ₇ type,
A hydrogen storage alloy comprising an alloy that is at least one phase selected from phases having any of the PuNi ₃ type crystal structures or a similar crystal structure. R1 _1-ab Mg _a T2 _b (Ni _1-x M7 _x ) _z (15) where R1 is at least one element selected from rare earth elements including yttrium, and T2 is selected from Ca, Ti, Zr. At least one element, M7 is Co, Mn,
Fe, V, Cr, Nb, Al, Ga, Zn, Sn, C
at least one element selected from u, Si, P, and B, and a, b, x, and z are each 0 <a ≦ 0.6, 0 ≦
It is defined as b ≦ 0.5, 0 ≦ x ≦ 0.9, 2.5 ≦ z <4.5. 22. A compound represented by the following general formula (16),
2θ = 8- in X-ray diffraction pattern using uKα ray
The intensity ratio (I ₁ ) between the intensity of the strongest peak (I ₁ ) appearing in the range of 13 ° and the intensity of the strongest peak (I ₂ ) of all the peaks.
/ I ₂ ) containing an alloy having a value of less than 0.15. R4 _1-ab Mg _a M8 _b (Ni _1-x M9 _x ) _z (16) where R4 is a rare earth element containing yttrium and C
at least one element selected from a, M8 is an element having a higher electronegativity than Mg (except for R4, Ni and M9), and M9 is Co, Mn, Fe, V, Cr, Nb, A
1, at least one element selected from Ga, Zn, Sn, Cu, Si, P, and B, where a, b, x, and z are respectively 0 <a ≦ 0.6, 0 ≦ b ≦ 0.5, 0 ≦ x ≦ 0.
9, 2.5 ≦ z <4.5. 23. A ₂ B ₄ subcell and AB ₅ a laminated structure of the subcell (where, A is the heat of formation ΔH hydride for 1 mole of hydrogen at 25 ℃ (kJ / mol) is 2
One or more elements smaller than 0 kJ / mol, B represents one or more elements having a heat of formation ΔH (kJ / mol) of 20 kJ / mol or more), and the A ₂ B ₄ subcell with respect to the AB ₅ subcell number Number ratio X is 0.5 <X <1
A hydrogen storage alloy comprising a crystal phase consisting of a unit cell. 24. The hydrogen storage alloy according to claim 23, wherein said A ₂ B ₄ subcell has a Loves structure, and said AB ₅ subcell is of a CaCu ₅ type. 25. The unit cell comprises n [LCLC
C] (where, L is A ₂ B ₄ subcell, C is AB ₅ subcell, n represents an integer) hydrogen claims 23 to 24 any one of claims characterized by having a layered structure represented by Storage alloy. 26. A wherein at least one element selected from the group consisting of rare earth elements including Y and Mg, and B is N
27. The method according to claim 23, wherein i is included.
The hydrogen storage alloy according to the item. 27. A secondary battery comprising a negative electrode containing the hydrogen storage alloy according to claim 1. Description: