JP2001048547A - Spinel-type lithium-manganese multiple oxide, its production and use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new lithium-manganese multiple oxide excellent in both cycle characteristics and preservability at high temperatures and high in dis charge capacity per volume as well when used as the anode active substance of lithium ion batteries, and to provide a lithium ion secondary battery using such a new lithium-manganese multiple oxide as anode active substance. SOLUTION: This new spinel-type lithium-manganese multiple oxide is represented by the formula Li(x+y)Mn(2-y-p-q)M1pM2qO(4-a)Fa (1.0<=x<1.2, 0<y<=0.2, 1.0<x+y<=1.2, 0<p<=1.0, 0.0005<=q<=0.1, 0<=a<=1.0; M1 is at least one metal atom selected from Ni, Co, Mg, Fe, Al and Cr; M2 is at least one element selected from those whose oxides are <=800 deg.C in melting point, respectively), being pref. 0.1-2.0 m2/g in specific surface area. The other objective lithium ion secondary battery is such as to have the anode containing the above new spinel-type lithium-manganese multiple oxide as anode active substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lithium-manganese composite oxide having a spinel structure, which is useful as a positive electrode active material for a lithium ion secondary battery, and a method for producing the same. The present invention also relates to a lithium ion secondary battery using the lithium-manganese composite oxide as a positive electrode active material.

[0002]

BACKGROUND OF THE INVENTION As a positive electrode active material constituting a positive electrode of a lithium ion battery, lithium cobaltate, lithium nickelate, lithium manganate and the like have been developed, including some practical applications. Among them, lithium cobalt oxide has a problem that the raw material cobalt is expensive and the effective charge amount is only about 50% of the theoretical amount. Lithium nickelate has the characteristics that it is inexpensive and has an effective storage capacity of about 1.4 times that of lithium cobaltate, but has some problems in safety. Lithium manganate, on the other hand, has a slightly lower effective storage capacity than lithium cobalt oxide, but it is used as a positive electrode active material for lithium ion batteries because manganese as a raw material is inexpensive and has the same safety as lithium cobalt oxide. Expected.

However, in a conventional lithium ion battery using lithium manganate as a positive electrode active material, when charge and discharge are repeated, the discharge capacity gradually decreases, that is, the so-called cycle characteristics are inferior to lithium cobalt oxide. There was a problem. This is considered to be because the manganese in the positive electrode active material is dissolved in the electrolytic solution, and furthermore, the discharge capacity is gradually reduced due to the generation of distortion of the lithium manganate crystal due to repeated charge and discharge.

Various lithium-manganese composite oxides have been proposed to solve the above-mentioned problems when using lithium manganate as a positive electrode active material. For example, a part of manganese of lithium manganate is changed to Al, Ni,
Lithium-manganese composite oxides that have been substituted with metal elements such as Co, Fe, Cr, Ta, V, Ti, and Mg have been proposed (JP-A-2-220358, JP-A-4-141).
954, JP-A-6-187993 and JP-A-9-147867). Further, a lithium-manganese composite oxide in which a part of manganese is replaced with boron has also been proposed (see Japanese Patent Application Laid-Open Nos. 4-237970, 8-79215, 8-195200).

However, a conventional lithium-manganese composite oxide in which a part of these manganese is substituted by a different element has a poor high-temperature cycle characteristic or a high-temperature cycle characteristic is not always satisfactory. It was not enough for practical use. Further, these positive electrode active materials are processed into fine particles, blended in a positive electrode mixture, and used for forming a positive electrode. By the way, as much as possible of the positive electrode active material is filled in a battery of a fixed volume, so that the capacity of the battery can be improved. Although desirable, the amount of the positive electrode active material that can be mixed in the mixture is also limited.

Therefore, if a fine particulate positive electrode active material having a high packing density is used, the weight of the positive electrode active material filled per unit volume increases, and a battery having a large charge / discharge capacity can be obtained. That is, a positive electrode active material having a large discharge capacity per volume (discharge capacity per weight x packing density) at the same time as a discharge capacity per weight is preferable. However, the conventional lithium manganate fine particles have a smaller packing density than lithium cobalt oxide having the same particle size, and the positive electrode active material using such lithium manganate has a low discharge capacity per volume and a low cobalt oxide. 50 of lithium
There is also a problem that it is only about 60%.

[0007]

An object of the present invention is to solve the above-mentioned problems of the conventional lithium-manganese composite oxide, and when used as a positive electrode active material of a lithium ion battery, the cycle characteristics and storage at high temperatures are improved. Provided is a novel lithium-manganese composite oxide having excellent dischargeability and a high discharge capacity per volume, a method for producing the same, and a lithium-ion secondary battery using such a novel lithium-manganese composite oxide as a positive electrode active material The purpose is to do.

[0008]

SUMMARY OF THE INVENTION The spinel-type lithium-manganese composite oxide according to the present invention is represented by the following general formula. _{Li (x + y) Mn (} 2-ypq) M1 p M2 q O (4-a) F a ( wherein, 1.0 ≦ x <1.2, 0 <y ≦ 0.2, 1.0 <x +
y ≦ 1.2, 0 <p ≦ 1.0, 0.0005 ≦ q ≦ 0.1, 0 ≦ a
≦ 1.0, M1: at least one metal selected from Ni, Co, Mg, Fe, Al, and Cr; M2: at least one element selected from elements having an oxide melting point of 800 ° C. or less) The specific surface area of the spinel-type lithium-manganese composite oxide is preferably in the range of 0.1 to 2.0 m ² / g.

The method for producing a spinel-type lithium-manganese composite oxide according to the present invention comprises: (i) a lithium compound;
Manganese compounds, (iii) Ni, Co, Mg, Fe, Al, Cr
A compound of at least one metal (M1) selected from
v) at least one compound selected from the elements (M2) having an oxide melting point of 800 ° C. or lower, and (v) a fluorine compound, wherein the atomic ratio of Li: Mn: M ₁ : M ₂ : F is (x + y) : (2-
ypq): p: q: a (where 1.0 ≦ x <1.2, 0
<Y ≦ 0.2, 1.0 <x + y ≦ 1.2, 0 <p ≦ 1.0, 0.0005 ≦
(q ≦ 0.1, 0 ≦ a ≦ 1.0) to prepare a water suspension, and drying the water suspension, followed by firing at a temperature of 650 to 900 ° C.

[0010] The lithium ion secondary battery according to the present invention comprises:
A positive electrode including the spinel-type lithium-manganese composite oxide as a positive electrode active material is provided.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The spinel-type lithium-manganese composite oxide according to the present invention is represented by the following general formula. _{Li (x + y) Mn (} 2-ypq) M1 p M2 q O (4-a) F a ( wherein, 1.0 ≦ x <1.2, 0 <y ≦ 0.2, 1.0 <x +
y ≦ 1.20 <p ≦ 1.0, 0.0005 ≦ q ≦ 0.1, 0 ≦ a ≦
1.0, M1: at least one metal selected from Ni, Co, Mg, Fe, Al, and Cr; M2: at least one element selected from elements having an oxide melting point of 800 ° C. or less. Such a lithium-manganese composite oxide has a spinel structure, and further has a structure in which part of the manganese atoms in the crystal structure is replaced by metal M1 and element M2, and part of the manganese atoms is further replaced by lithium atoms. It is estimated that it has.

The substitution amount of the metal M1 is 0 <p ≦ 1, preferably 0.02 ≦ P ≦ 0 in the general formula.
2 range. Within such a range, when used as a positive electrode active material, a constant discharge capacity can be secured and high-temperature cycle characteristics can be maintained. In addition, when the substitution amount of the metal M1 is increased, the high-temperature cycle characteristics of the battery when used as the positive electrode active material are improved, but the discharge capacity of the battery may be reduced.

As the element M2 whose melting point of the oxide is 800 ° C. or less, specifically, B (B ₂ O ₃ ; melting point: 460 ° C.), P
(P ₂ O ₅ ; melting point 420 ° C.), Pb (PbO; melting point 290)
_{℃), Sb (Sb 2 O} 3; mp _{655 ℃), V (V 2} O 5;
Melting point 680 ° C.). Among these, a particularly preferred element is B or V. These elements M2
Is considered to constitute a structure in which a part of Mn is substituted in the finally obtained lithium-manganese composite oxide.

The amount of M2 in the above general formula is 0.1.
0005 ≦ q ≦ 0.1, preferably 0.005 ≦ q ≦
It is desirably in the range of 0.05. If the element M2 is contained within the above range in the lithium-manganese composite oxide, the obtained lithium-manganese composite oxide has sufficiently grown crystals. When q is less than 0.0005, the effects of crystal growth and fine particle sintering cannot be expected, and when q exceeds 0.1, the discharge capacity of the battery when used as a positive electrode active material may decrease.

In the present invention, these elements M2 are added to promote the formation and growth of spinel crystals. That is, during the spinel crystal formation process, these elements M2 promote the generation and growth of the crystal by the oxide of the above element acting as a flux, and further, the fine particles (primary particles) in which the crystal particles (primary particles) are aggregated. Secondary particles). As a result, a very dense lithium-manganese composite oxide having a small specific surface area can be obtained.

That is, the spinel-type lithium-manganese composite oxide according to the present invention has a crystal particle (primary particle) having a particle size in the range of 0.1 to 5.0 μm, and an approximately sintered particle obtained by assembling the primary particle. consists secondary particles in the range of 2 to 30 m, a specific surface area, 0.1~2.0m ² / g, preferably from 0.2~0.8m ² / g, packing density, 1.
It is in the range of 5-2.5 g / ml.

The above-mentioned spinel-type lithium-manganese composite oxide fine particles have a higher packing density than conventional lithium-manganese composite oxides when filled in a container having a fixed volume. Therefore, when used as a positive electrode active material, the weight of the positive electrode active material that can be filled in a battery of a fixed volume increases, and the discharge capacity per volume can be increased as compared with a conventional positive electrode active material.

Further, when the crystal is sufficiently grown and is used as a positive electrode active material, the amount of Mn dissolved in the electrolytic solution when contacted with the electrolytic solution is smaller than that of the conventional lithium-manganese composite oxide. Since it is less at high temperatures, there is little decrease in discharge capacity due to repeated charging and discharging at high temperatures.
That is, the high-temperature cycle characteristics can be improved.

If the specific surface area is smaller than 0.1 m ² / g, the dissolution amount of Mn is reduced, but the contact between the positive electrode active material and the conductive agent and the contact with the electrolyte in the positive electrode may be insufficient. is there. On the other hand, if it is more than 2.0 m ² / g, the packing density becomes small, and the discharge capacity per volume may not be improved, or the cycle characteristics may not be improved due to the increase in the amount of dissolved Mn.

In the lithium-manganese composite oxide according to the present invention, Mn is partially replaced with Li. The theoretical value of Li in a lithium-manganese composite oxide having a spinel structure used as a positive electrode active material of a lithium ion battery is 1, but in the present invention, Li is included in excess of the theoretical value. By reducing the amount of Mn by an amount corresponding to part or all of the excess Li, a structure is obtained in which at least a part of Li is substituted with Mn. That is, in the above general formula, the total amount (x + y) of Li is 1.0 <
(X + y) ≦ 1.2, preferably 1.05 <(x + y)
It is desirable to be in the range of ≦ 1.15. Further, the Li amount (y) substituted with Mn is desirably in the range of 0 <y ≦ 0.2, preferably 0.05 <y ≦ 0.15. When the Li replacement amount (y) increases, the charge and discharge capacity of the battery slightly decreases, but the cycle characteristics improve. However, even if y is more than 0.2 (x + y is 1.2), the effect of improving the cycle characteristics is not seen. Also, L
When the total amount (x + y) becomes 1.0 or less, a hetero phase serving as an impurity is generated, and the charge / discharge performance of the battery is reduced.

In the spinel-type lithium-manganese composite oxide according to the present invention, the lithium-manganese composite oxide may further contain fluorine. This fluorine is presumed to have a structure in which a part of oxygen is substituted in the spinel structure. By using the positive electrode active material to which fluorine is added, the charge / discharge capacity of the lithium ion battery can be increased.

The lithium-manganese composite oxide of the present invention can be produced, for example, by mixing powders of a lithium compound, a manganese compound and compounds of the elements M1 and M2, and firing the mixture in an oxygen-containing gas atmosphere. it can. Particularly preferred is an aqueous suspension in which a lithium compound, a manganese compound, compounds of the elements M1, M2 and a fluorine compound are mixed at a predetermined ratio based on Japanese Patent Application Laid-Open No. Hei 10-172567 filed by the present applicant. Is prepared, dried, and then fired at 650 to 900 ° C.

Hereinafter, the manufacturing method according to the present invention will be specifically described. First, an aqueous suspension in which a manganese compound, a substituting element M1 compound and a fluorine compound are dispersed in water or a part of which is dissolved (hereinafter referred to as an aqueous suspension A) is prepared. As the manganese compound, a manganese oxide such as electrolytic manganese dioxide or chemically synthesized manganese dioxide, or a manganese compound which is thermally decomposed to manganese dioxide such as manganese hydroxide, manganese carbonate, or manganese nitrate is used. It is preferable that such a manganese compound is previously adjusted to have an average particle diameter of 10 μm or less, preferably 0.1 to 5 μm by means such as grinding.

The element M1 (Ni, Co, Mg, Fe, Al, Cr)
Examples of the compound include one or more metals selected from the group consisting of carbonates such as basic nickel carbonate and basic cobalt carbonate, and oxides such as alumina and magnesia. The average particle diameter of these compounds is preferably adjusted to 10 μm or less, preferably 0.1 to 5 μm, similarly to the manganese compound.

The particle size adjustment may be performed separately for each of the above compounds, or may be performed after all of the above compounds are mixed. If the average particle size of the solids in the aqueous suspension is adjusted to such a range, the solids in the suspension are not subjected to solid-liquid separation, and are subjected to the next drying step in a uniform state. be able to. As a result, a dry powder in which each compound is mixed very uniformly is obtained. Then, if this dried material is fired, the solid phase reaction with manganese, lithium, and the substitution element easily proceeds, and it is possible to obtain a higher-purity composite oxide than a fired product of a conventional mixture of solid powders. it can. In the case where elemental fluorine is added, for example, ammonium fluoride, hydrofluoric acid, lithium fluoride, and the like are mixed into the above-mentioned aqueous suspension A.

In the aqueous suspension A prepared as described above, a compound of the element M2 whose melting point of the lithium compound and the oxide is 800 ° C. or less is mixed. Examples of the lithium compound include water-soluble lithium compounds such as lithium hydroxide, lithium carbonate, and lithium nitrate. Examples of the compound of M2 include an acid containing the element M2, a water-soluble salt, and the like. Specifically, a water-soluble boron compound such as boric acid and borax;
Water-soluble vanadium compounds such as ammonium metavanadate are exemplified.

The compound of the element M2 whose melting point of the above-mentioned lithium compound and oxide is 800 ° C. or less may be directly mixed with the prepared water suspension A. It may be mixed with the liquid A. Lithium compound, manganese compound, element M prepared as described above
1. An aqueous suspension containing a compound of M2 and a fluorine compound at a predetermined ratio (hereinafter referred to as an aqueous suspension B) has a solid content concentration of 5 to 30% by weight by adding new water or the like. It is desirable to adjust to.

The aqueous suspension B prepared by the above method is then subjected to a drying operation. The drying method is not particularly limited, and examples thereof include a method using a spray drier, a band drier, a shelf type drier and the like. In particular, if a spray dryer is used, spherical lithium / manganese composite oxide fine particles can be obtained. At this time, the drying temperature of the hot air for drying of the spray dryer is about 2
Preferably, the temperature ranges from 90 to 310C and the outlet temperature ranges from about 110 to 120C.

The dried fine particles are then fired in an oxygen-containing gas atmosphere at a temperature in the range of 650 to 900 ° C. By this firing operation, lithium with spinel structure
As the manganese composite oxide is generated and the crystal growth proceeds, sintering of the fine particles (secondary particles) in which the crystal particles are aggregated is promoted, and the above-described lithium-manganese composite oxide is obtained.

The calcination is carried out in a usual calcination furnace such as a tunnel furnace, a muffle furnace and a rotary kiln in an oxygen-containing gas such as air. The specific surface area of the lithium-manganese composite oxide of the present invention decreases as the firing temperature is increased or the amount of the compound of the element M2 acting as a flux increases. In the present invention, the element M2
By appropriately selecting the sintering temperature in accordance with the added amount of, a lithium-manganese composite oxide having a specific surface area of 0.1 to 2.0 m ² / g can be obtained.

Further, if calcination is carried out at a temperature within the above range, sintering of fine particles (secondary particles) in which crystal particles are aggregated proceeds, and dense fine particles having a higher packing density than the secondary particles obtained by a conventional method are obtained. Can be

[0032]

In the lithium-manganese composite oxide according to the present invention, a part of Mn is replaced by a metal element selected from Ni, Co, Mg, Fe, Al and Cr, and this is used as a positive electrode active material. The used lithium ion battery is excellent in high temperature characteristics such as high temperature storage stability and high temperature cycle characteristics.

Further, the melting point of the oxide such as B is 800 ° C.
Since the following elements are added, the crystals grow sufficiently, and the fine particles, which are aggregates of the crystal particles, are sufficiently sintered, so that the specific surface area is small and the packing density of the fine particles is large. Accordingly, a lithium ion battery using this as a positive electrode active material has excellent discharge capacity per volume, and at the same time, Ni,
It is more improved than the substitution with only metal elements such as Co, Mg, Fe, Al and Cr.

Further, since part of Mn is replaced with Li, a lithium ion battery using this as a positive electrode active material has improved high-temperature cycle characteristics. Furthermore, when the lithium-manganese composite oxide according to the present invention is obtained by replacing a part of oxygen with fluorine as a positive electrode active material,
The charge / discharge capacity of the lithium ion battery can be improved.

[0035]

EXAMPLES Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[0036]

EXAMPLE 1 Electrolytic manganese dioxide powder (γ-MnO ₂ , purity 92%) and cobalt carbonate powder (CoCO ₃ , purity 93)
%) In a wet crusher at a ratio of Mn: Co = 90: 10 (atomic ratio) and crushed to an average particle size of 0.5 μm. Add Li: Co: Mn: B = 1.1: 0.
189: 1.701: 0.0095 (atomic ratio), an aqueous solution of lithium hydroxide and an aqueous solution of boric acid are added.
A slurry having a solid content of 20% by weight was prepared.

This slurry was dried with a spray drier. The condition of the spray dryer is hot air inlet temperature 30
0 to 310 ° C and outlet temperature of 110 to 150 ° C. Next, the dried powder was calcined at 850 ° C. for 6 hours under air flow to obtain Li _1.1 Co _0.189 Mn _1.701 B _0.0095 O ₄ (x =
1.0, y = 0.1).
Fine particles of a manganese composite oxide were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the fine particles. In addition, the measuring method is as follows. Average particle size: Laser diffraction scattering type particle size distribution measuring device (LA-700, manufactured by Horiba Ltd.) Specific surface area: Automatic surface area measuring device (Multisoap-12, manufactured by Yuasa Ionics Inc.) Collect 25g,
After tapping on a wooden table for 3 minutes, the volume (V) was measured and determined by the following equation.

Packing density (g / ml) = 25 / V

[0040]

EXAMPLE 2 The atomic ratio of lithium, cobalt, manganese and boron is Li: Co: Mn: B = 1.1: 0.09.
Except that the raw materials were blended so as to be 5: 1.796: 0.0095, Li _1.1 was obtained under the same synthesis conditions as in Example 1.
Co _0.095 Mn _1.796 B _0.0095 O ₄ (x = 1.0, y = 0.
Fine particles of the crystalline lithium / manganese composite oxide comprising 1) were prepared.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0042]

Embodiment 3 The atomic ratio of lithium, cobalt, manganese and boron is Li: Co: Mn: B = 1.1: 0.01.
Except that the raw materials were blended so as to be 9: 1.872: 0.0095, Li _1.1 Co was used under the same synthesis conditions as in Example 1.
_0.019 Mn _1.872 B _0.0095 O ₄ (x = 1.0, y = 0.1)
Fine particles of a crystalline lithium-manganese composite oxide were prepared.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0044]

Embodiment 4 The atomic ratio of lithium, cobalt, manganese and boron is Li: Co: Mn: B = 1.1: 0.09.
2: 1.751: except that blended raw material to be 0.057, the synthesis conditions as in Example 1, Li _1.1 Co
_0.092 Mn _1.751 B _0.057 O ₄ (x = 1.0, y = 0.1)
Fine particles of a crystalline lithium-manganese composite oxide were prepared.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0046]

Embodiment 5 γ-Al ₂ O as an aluminum compound
₃ (purity: 95%) using lithium, aluminum,
The atomic ratio of manganese and boron is expressed as Li: Al: Mn: B =
Under the same synthesis conditions as in Example 1 except that the raw materials were blended so as to be 1.1: 0.095: 1.796: 0.0095, Li _1.1 Al _0.095 Mn _1.796 B _0.0095 O ₄ (x = 1 .
(0, y = 0.1) to obtain fine particles of a crystalline lithium-manganese composite oxide.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0048]

Example 6 Using magnesium oxide (MgO, purity: 99.8%) as a magnesium compound, lithium,
The atomic ratio of magnesium, manganese and boron is Li:
Mg: Mn: B = 1.1: 0.047: 1.843: 0.
Example 1 except that the raw materials were blended so as to be 0095.
In the same synthesis conditions _{as, Li 1.1 Mg 0.047 Mn 1.843 B} 0.00 95
Fine particles of a crystalline lithium / manganese composite oxide composed of O ₄ (x = 1.0, y = 0.1) were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0050]

Embodiment 7 Nickel hydroxide (N
i (OH) ₂ , purity: 100%). The atomic ratio of lithium, nickel, manganese and boron is Li: Ni: M
n: B = 1.1: 0.095: 1.796: 0.009
5, Li _1.1 Ni _0.095 Mn _1.796 B _0.0095 O under the same synthesis conditions as in Example 1, except that the raw materials were blended.
₄ (x = 1.0, y = 0.1) to obtain fine particles of crystalline lithium / manganese composite oxide.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0052]

Embodiment 8 Chromic anhydride (Cr) was used as a chromium compound.
O ₃ , purity: 99.8%), lithium, chromium,
When the atomic ratio of manganese and boron is Li: Cr: Mn: B =
Under the same synthesis conditions as in Example 1 except that the raw materials were blended so as to be 1.1: 0.095: 1.796: 0.0095, Li _1.1 Cr _0.095 Mn _1.796 B _0.0095 O ₄ (x = 1 .
(0, y = 0.1) to obtain fine particles of a crystalline lithium-manganese composite oxide.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0054]

Embodiment 9 Iron oxide (Fe ₂ O ₃ , purity: 9) was used as an iron compound.
8%), the atomic ratio of lithium, iron, manganese and boron is Li: Fe: Mn: B = 1.1: 0.047:
1.83: Li _1.1 Fe _0.047 under the same synthesis conditions as in Example 1 except that the raw materials were blended so as to be 0.0095.
_Fine particles of a crystalline lithium-manganese composite oxide composed of Mn _1.843 B _0.0095 O ₄ (x = 1.0, y = 0.1) were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0056]

Example 10 Electrolytic manganese dioxide powder (γ-MnO ₂ ,
Purity 92%) and nickel hydroxide powder (Ni (OH) ₂ , purity 100%) were charged into a wet mill at a ratio of Mn: Ni = 95: 5 (atomic ratio) and milled to an average particle size of 0.5 μm. did.
To this mixture slurry, Li: Ni: Mn: B: F = 1.
1: 0.095: 1.796: 0.0095: 0.09
An aqueous solution of lithium hydroxide, an aqueous solution of boric acid and an aqueous solution of ammonium fluoride were added so as to have an atomic ratio of 5 to prepare a slurry having a solid content of 20% by weight.

This slurry was dried with a spray drier under the same conditions as in Example 1. Then, the dried powder is calcined at 850 ° C. for 6 hours under air flow to obtain Li _1.1 Ni.
_0.095 Mn _1.796 B _0.0095 O _3.905 F _0.095 (x = 1.0,
y = 0.1) to obtain fine particles of crystalline lithium / manganese composite oxide. Table 1 shows the average particle size, specific surface area, and packing density of the obtained fine particles.

[0058]

Embodiment 11 Lithium, nickel, manganese, boron and the like
And the atomic ratio of fluorine and Li: Ni: Mn: B: F = 1.
1: 0.095: 1.796: 0.0095: 0.19
Synthesis conditions similar to Example 10 except that
And Li_1.1Ni_0.095Mn_1.796B _0.0095O_3.81F_0.19(X
= 1.0, y = 0.1)
Fine particles of the gun complex oxide were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0060]

Comparative Example 1 Li _1.1 Co _0.095 Mn _1.805 O ₄ (x = _{1.10) under} the same synthesis conditions as in Example 1 except that boron was not added and the amounts of lithium and cobalt were the same as in Example 2.
(0, y = 0.1) to obtain fine particles of a crystalline lithium-manganese composite oxide. Average particle size of the obtained fine particles,
Table 1 shows the specific surface area and packing density.

[0061]

Comparative Example 2 The synthesis conditions were the same as in Example 1 except that the atomic ratio of lithium, manganese and boron was set to Li: Mn: B = 1.1: 1.89: 0.0095.
Li _1.1 Mn _1.89 B without substitution elements other than Li and B
_Fine particles of crystalline lithium / manganese composite oxide composed of _0.0095 O ₄ (x = 1.0, y = 0.1) were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0063]

[Comparative Example 3] The Li was the theoretical amount, except that the same substitution of Co and B as in Example 2, the synthesis conditions as in Example _{1, Li 1.0 Co 0.10 Mn 1.89} B 0.0095 O 4 (x = 1.
(0, y = 0) to obtain fine particles of a crystalline lithium-manganese composite oxide. Table 1 shows the average particle size, specific surface area, and packing density of the obtained fine particles.

[0064]

Comparative Example 4 The powders of electrolytic manganese dioxide, cobalt carbonate, lithium hydroxide and boric acid used in Example 1 were obtained by adding Li: Co: Mn: B = 1.1: 0.095: 1.7.
It was collected in a mortar so that the ratio became 96: 0.0095 (atomic ratio), crushed, and then mixed. Next, the mixture was calcined at 850 ° C. for 6 hours under flowing air to _obtain Li _1.1 Co _0.095 Mn.
_Fine particles of crystalline lithium / manganese composite oxide composed of _1.796 B _0.0095 O ₄ (x = 1.0, y = 0.1) were obtained.

Table 1 shows the average particle size, specific surface area and packing density of the obtained fine particles.

[0066]

[Table 1]

[0067]

Example 12 A test lithium ion battery was prepared using the positive electrode containing the crystalline lithium / manganese composite oxide obtained in Examples 1 to 11 as a positive electrode active material, and the battery performance was evaluated. First, fine particles of each crystalline lithium-manganese composite oxide, acetylene black as a conductive material, and polytetrafluoroethylene powder as a binder are mixed at a weight ratio of 75: 20: 5, and kneaded in a mortar. A mixture for a positive electrode was prepared. This mixture was formed into a sheet having a thickness of 0.1 mm with a spreading roller, and then punched out to a diameter of 16 mm.
Vacuum drying was performed at 10 ° C. to prepare a test positive electrode.

These positive electrodes and a metallic lithium foil (thickness: 0.
2 μm) was laminated on a coin-type battery case via a separator (trade name: Celgard), and 1: 1 in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 1.
A test battery was prepared by injecting an electrolytic solution in which mol / l of LiPF ₆ was dissolved. The above batteries were subjected to a discharge capacity, a high-temperature cycle characteristic, and a high-temperature deterioration test. (1) Discharge capacity Current density of 0.5 mA / cm ² at constant current, charge potential 4.3
The discharge capacity per unit weight was first measured under the conditions of potential regulation up to 3.0 V, and the discharge capacity per unit volume was calculated by the following equation.

Discharge capacity per volume = discharge capacity per weight × packing density (2) High temperature cycle characteristics A test battery was placed in a thermostat at 60 ° C., and a charge / discharge test was performed 30 times under the same conditions as above. The high-temperature cycle characteristics were evaluated based on the capacity retention rate of the following equation. Capacity retention rate (%) = (Discharge capacity per weight for the first time / 3)
(0th discharge capacity per weight) x 100 (3) High temperature deterioration test (evaluation of high temperature storage property) Performance degradation of positive electrode active material after immersion in high temperature electrolyte for a certain period of time, using recovery rate of discharge capacity as index evaluated.

First, a positive electrode active material sample was dried at 110 ° C. for 3 hours, and about 10 g of the sample was collected in a 50 ml-capacity stainless steel container with a lid. This was transferred into an argon gas circulation glove box having a dew point of about -70 ° C., and 1 part by volume of a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 1.
10 ml of an organic solvent in which mol / l of LiPF ₆ was dissolved was added.
After the container was closed, it was taken out of the glove box, transferred to a thermostat set at 85 ° C., and kept for 7 days. Next, the container was taken out and cooled to room temperature. Then, the sample in the container and the organic solvent were separated by filtration and dried at 110 ° C. for 3 hours.

Using the thus treated positive electrode active material,
A test positive electrode and a test battery similar to the above were prepared. Perform the charge and discharge test of these test electrodes under the above conditions,
The recovery rate was calculated by the following equation. A: Discharge capacity of battery using untreated cathode active material B: Discharge capacity of battery using untreated cathode active material Recovery rate (%) = (A / B) × 100 (The discharge capacity is 2 Table 2 shows the results of the discharge capacity, high-temperature cycle characteristics, and recovery rate obtained above.

[0072]

Comparative Example 5 The crystalline lithium obtained in Comparative Examples 1 to 4
Using a positive electrode containing a manganese composite oxide as a positive electrode active material, a test lithium ion battery was prepared in the same manner as in Example 12, and the battery performance was evaluated. Table 2 shows the results.

[0073]

[Table 2]

The following can be seen from the above Examples and Comparative Examples. (1) Comparing Example 2 and Comparative Example 1 having the same composition except for the presence or absence of boron, Example 2 has a smaller specific surface area,
High packing density. Therefore, both the capacity retention rate and the recovery rate are superior to Comparative Example 1. (2) Compared to Example 1 and Comparative Example 2 having the same composition except for the presence or absence of the substituted metal M1, Example 1 is superior in both the capacity retention rate and the recovery rate. (3) When the theoretical amount of lithium is (1.0) as in Comparative Example 3, the capacity retention ratio is inferior to each of the examples in which lithium is at least 1.0 and Mn is substituted. (4) As in Examples 10 and 11, when fluorine is added to Example 7, the discharge capacity is improved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 4/58 H01M 4/58 10/40 10/40 Z (72) Inventor Shigeo Nishiwaki Niitsu, Niigata 1-26 Ichitaki Honmachi, JGC Chemicals Development Research Laboratory (72) Inventor Masayuki Hoshina 1-26, Takitani Honmachi, Niitsu City, Niigata Prefecture JGC Chemicals Corporation R & D Laboratory F-term (reference) AE05 4G048 AA04 AA05 AB05 AC06 AD04 AD06 AE05 AE06 5H003 AA07 BA01 BA03 BB05 BC06 BD00 BD01 BD05 5H014 AA02 BB01 BB06 HH00 HH08 5H029 AJ14 AK03 AL12 AM03 AM07 BJ03 CJ02 CJ08 HJ02 HJ07

Claims (4)

[Claims] 1. A spinel-type lithium / manganese composite oxide represented by the following general formula. _{Li (x + y) Mn (} 2-ypq) M1 p M2 q O (4-a) F a ( wherein, 1.0 ≦ x <1.2, 0 <y ≦ 0.2, 1.0 <x +
y ≦ 1.2, 0 <p ≦ 1.0, 0.0005 ≦ q ≦ 0.1, 0 ≦ a
≦ 1.0, M1: at least one metal selected from Ni, Co, Mg, Fe, Al, and Cr; M2: at least one element selected from elements having an oxide melting point of 800 ° C. or less) 2. The spinel-type lithium-manganese composite oxide according to claim 1, wherein the specific surface area is in the range of 0.1 to 2.0 m ² / g. 3. A compound of at least one metal (M1) selected from (i) a lithium compound, (ii) a manganese compound, (iii) Ni, Co, Mg, Fe, Al and Cr, and (iv) an oxide. At least one compound selected from the elements (M2) having a melting point of 800 ° C. or less, and (v) a fluorine compound, wherein the atomic ratio of Li: Mn: M1: M2: F is (x + y) :( 2-
ypq): p: q: a (where 1.0 ≦ x <1.2, 0
<Y ≦ 0.2, 1.0 <x + y ≦ 1.2, 0 <p ≦ 1.0, 0.0005 ≦
(q ≦ 0.1, 0 ≦ a ≦ 1.0) to prepare a water suspension, and after drying the water suspension, calcination at a temperature of 650 to 900 ° C. A method for producing a lithium-manganese composite oxide. 4. A lithium ion secondary battery having a positive electrode containing the spinel-type lithium-manganese composite oxide according to claim 1 as a positive electrode active material.