JP2001068113A - Positive electrode active material for lithium battery, its manufacturing method, and lithium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high discharging capacity, high stability and a wide operating temperature range by specifying the amount of lithium in a transition metal main layer in a layer structure of a composite oxide containing Li, Ni, Co, M, and O in a specified rate and having the layer structure. SOLUTION: This positive electrode active material for a lithium battery is a composite oxide having layer structure, represented by the composition formula: LiXNi1-Y-QCoQMYOZ. In the formula, 0<=X<=1.1, 0<Y+Q<0.5, 0<Y<0.5, 0<Q<0.5, 1.8<=Z<=2.2, and M is an element such as silicon, titanium, or the like. A rate of lithium in the transition metal main layer in the structure is 0.5% or more but 15% or less. Ni, Co, and element M contained mainly in the transition metal main layer in the structure are hardly mixed with lithium contained in the lithium main layer, change to randomly arranged rock-salt structure is retarded, and heat generation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode active material for a lithium battery and a method for producing the same, and a lithium battery using the same. More specifically, the present invention relates to a lithium battery having a large discharge capacity, excellent safety, and a wide operating temperature range. It is related to the technology to be provided.

[0002]

2. Description of the Related Art A non-aqueous electrolyte battery using an alkali metal such as lithium or a compound thereof as a negative electrode active material is disclosed in
The large discharge capacity and charge / discharge reversibility are both achieved by the insertion or intercalation reaction of the negative electrode metal ions into the positive electrode active material. Conventionally, sulfides such as titanium disulfide have been proposed for these positive electrode active materials, but these have the drawback that the voltage is as low as about 2 V and the discharge energy is small. To solve this problem, the positive electrode active indicating the 4V-grade voltage substance Li _X Ni _1-Y M _Y
O _Z (0 ≦ X ≦ 1.1, 0 ≦ Y ≦ 0.5, 1.8 ≦ Z ≦
2.2, element M is an element other than nickel). This makes it possible to realize a large capacity, but at the same time, a compound having a high oxidation state is accommodated in the battery due to lithium elimination, which may cause a problem in the safety of the whole battery. Was.

[0003] That is, the battery generates heat when the environmental temperature is high or the battery is short-circuited under high voltage, particularly when the battery is fully charged, and in extreme cases, smoke or ignition occurs. There was a safety problem that was seen. If the amount of lithium released during charging is too large,
In particular, when the operating temperature is high, the positive electrode cannot maintain the original crystal structure, the subsequent discharge capacity decreases, and the operating temperature range is limited.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned current problems, and provides a positive electrode active material for a lithium battery having a large discharge capacity, excellent safety, and a wide operating temperature range, and a method for producing the same. And a lithium battery using the same.

[0005]

Means for Solving the Problems In order to achieve the above object, the positive electrode active material for a lithium battery according to the present invention is a double oxide having a layer structure given by the following composition formula. Wherein the lithium occupancy of the transition metal main layer is 0.5% or more and 15% or less.

[0006] formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0 <Y + Q <0.5,0 <Y <0.
5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2, M is silicon,
One or more elements including any of titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, lead)

[0007] Further, the positive electrode active material for a lithium battery is characterized in that the element M particularly contains titanium.

Further, in the method for producing a cathode active material for a lithium battery according to the present invention, the atomic ratio of Li / (Ni + Co + M)> 1
After mixing a lithium compound, a nickel compound, a cobalt compound, and a compound of the element M and heat treating the mixture so as to obtain a lithium compound other than Li _x Ni _{1 -YQ} Co _Q M _Y O _Z , It is characterized by producing a positive electrode active material for a lithium battery.

The lithium battery of the present invention has a positive electrode containing the positive electrode active material for a lithium battery, particularly a positive electrode containing the positive electrode active material for a lithium battery manufactured by the method for producing the positive electrode active material for a lithium battery. A negative electrode containing a lithium compound or a substance capable of reversibly inserting and removing lithium ions, wherein the lithium ions have a substance capable of performing migration for performing an electrochemical reaction with the positive electrode and the negative electrode as an electrolyte substance. And

The present invention will be described in more detail. The inventor has conducted a keen search for a lithium battery positive electrode active material having a large discharge capacity and excellent safety and a method for manufacturing the same, and a lithium battery using the same, and as a result, the positive electrode active material for a lithium battery and a method for manufacturing the same, and It was confirmed that a lithium battery using the same can produce and realize a positive electrode active material for a lithium battery and a lithium battery having a higher discharge capacity, higher safety and a wider operating temperature range than before, and completed the present invention based on that recognition. .

[0011] A positive active material of the present invention, the composition formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0
<Y + Q <0.5, 0 <Y <0.5, 0 <Q <0.5,
1.8 ≦ Z ≦ 2.2, M is silicon, titanium, vanadium,
Chromium, manganese, iron, germanium, zirconium,
Niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum,
(At least one element including any of lead).

In the above composition formula, X satisfies 0 ≦ X ≦ 1.1, which indicates a range that varies depending on charging and discharging of the lithium battery. Also, as described later in detail, 0 <Y + Q <0.
5, 0 <Y <0.5 and 0 <Q <0.5, where Y is preferably Y ≦ 0.3, and more preferably Y ≦ 0.1. Further, Q is preferably Q ≦ 0.3, more preferably Q ≦ 0.2. Z satisfies 1.8 ≦ Z ≦ 2.2, which indicates a range that varies depending on the values of Y and Q and the synthesis conditions.

The positive electrode active material for a lithium battery according to the present invention has a ratio of a redox couple based on Li _x NiO _Z of 5%.
It exceeds 0% (that is, Y + Q <0.5), and the lithium occupancy in the transition metal main layer is 0.5% or more and 15% or less as described in detail later. This has the advantage that a positive electrode active material for a lithium battery and a lithium battery having a large discharge capacity can be manufactured and realized. The lithium occupancy in the transition metal main layer is preferably 10% or less,
More preferably, it is 5% or less.

When the redox couple based on Li _x NiO _Z is 50% or less, or when the lithium occupancy in the transition metal main layer exceeds 15%, a sufficient discharge capacity cannot be obtained.

Further, in terms of atomic ratio, Li / (Ni + Co + M)>
The lithium was removed _{Li X Ni 1-YQ Co Q} M Y O Z other than lithium compound after heat treatment of the mixture by mixing a lithium compound and a nickel compound and a cobalt compound and a compound of the element M to be 1 By using the method for producing a positive electrode active material for a lithium battery of the present invention for producing a positive electrode active material for a battery, the nickel mixing ratio in the lithium main layer can be suppressed to about 5% or less, and the discharge capacity is large. It is preferable for forming a battery.

The use of the positive electrode active material for a lithium battery according to the present invention has an advantage that a lithium battery excellent in safety can be realized. The reason is not completely clear at present, but the following can be considered.

[0017] That composition formula _{Li X Ni 1-YQ Co Q} M Y O
_Z (0 ≦ X ≦ 1.1, 0 <Y + Q <0.5, 0 <Y <
0.5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2, M is silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, At least one element selected from the group consisting of tellurium, hafnium, tungsten, iridium, platinum, and lead), the lithium occupancy of the transition metal main layer in the layer structure is less than 0.5%. In some cases, when the voltage is high, especially when fully charged,
Nickel, cobalt, element M, and lithium in the lithium-based layer mainly in the transition metal-based layer in the structure are free when the environmental temperature rises or the battery causes an internal short circuit. Batteries generate heat and, in extreme cases, emit smoke or fire, due to mixing and change to a rock salt structure in which nickel, cobalt, element M and lithium are randomly arranged. When the lithium occupation ratio in the layer is 0.5% or more, it is difficult for nickel, cobalt, and the element M mainly in the transition metal main layer in the structure to freely mix with lithium in the lithium main layer. It is considered that a change to a rock salt structure in which nickel, cobalt, element M and lithium are randomly arranged is suppressed.

The lithium occupancy in the transition metal main layer may be 0.5% or more, and there is no particular upper limit from the viewpoint of safety. However, if it is too high, the discharge capacity is reduced. It is necessary to be 15% or less as shown in the invention. As described above, it is preferably at most 10%, more preferably at most 5%.

In order to make the lithium occupation ratio in the transition metal main layer 0.5% or more, silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium,
Tin, tellurium, hafnium, tungsten, iridium,
It is necessary to contain at least one kind of element M containing either platinum or lead.

The element M easily takes a +4 valence state, and forms a compound such as Li _R MO _{2 + R / 2} (R is a positive number), which is a compound containing lithium and oxygen, and forms Li _X Ni _{1 -Q} Co. _This is considered to be because solid solution with _Q O _Z can increase the lithium occupancy in the transition metal main layer. As the element M, titanium, manganese, iron, zirconium, molybdenum, silicon, germanium, tin, and lead are particularly preferable from the viewpoint of relatively abundant resources. Further, as the element M, titanium, vanadium, chromium, manganese, iron, and germanium are preferable from the viewpoint that the ionic radius is close to that of nickel + trivalent and the solid solution is easy, and titanium, manganese, Iron is particularly preferred.

In particular, titanium is obtained when M = Ti in the above-mentioned Li _R MO _{2 + R / 2} (R is a positive number), and R _1/3 of Li _1/3
TiO _13/6 (that is, Li ₂ Ti ₆ O ₁₃ ), R = 1/2 L
i _1/2 TiO _9/4 (that is, Li ₂ Ti ₄ O ₉ ), R = ２
Li _2/3 TiO _7/3 (that is, Li ₂ Ti ₃ O ₇ ), R = 1
2/17 Li _12/17 TiO _40/12 (ie Li ₁₂ Ti ₁₇
O ₄₀ ), R _4/5 Li _4/5 TiO _12/5 (that is, Li ₄
It is possible to easily synthesize a lithium titanate compound such as Ti ₅ O ₁₂ ) and Li ₂ TiO _{3 with} R = 2, and Li _X N
It is particularly preferable as the element M because it is easily dissolved in i _{1 -Q} Co _Q O _Z and the lithium titanate compound is stable around the synthesis temperature of Li _X Ni _{1 -Q} Co _Q O _Z.

On the other hand, when the content of the element M is high, the discharge capacity decreases, so that Y corresponding to the substitution amount of the element M becomes Y
<0.5, preferably Y ≦ 0.3,
Most preferably, Y ≦ 0.1. Further, by using the positive electrode active material for a lithium battery of the present invention, there is an advantage that a lithium battery and a positive electrode active material for a lithium battery having a wide operating temperature range can be manufactured and realized.

The reason is not completely clear at present, but the following can be considered. That composition formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0
<Y + Q <0.5, 0 <Y <0.5, 0 <Q <0.5,
1.8 ≦ Z ≦ 2.2, M is silicon, titanium, vanadium,
Chromium, manganese, iron, germanium, zirconium,
Niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum,
In the complex oxide given by one or more elements containing any of lead, Q corresponding to the substitution amount of cobalt is 0 <
By being Q, the amount of lithium desorbed during charging can be suppressed, and even when the operating temperature is high, the positive electrode can maintain the original crystal structure, the discharge capacity does not decrease, and the operating temperature range becomes wider. Conceivable. In order to construct a battery having a large discharge capacity, it is necessary that Q <0.5, preferably Q ≦ 0.3, most preferably Q ≦ 0.
2.

Also, in terms of atomic ratio, Li / (Ni + Co + M)>
The lithium was removed _{Li X Ni 1-YQ Co Q} M Y O Z other than lithium compound after heat treatment of the mixture by mixing a lithium compound and a nickel compound and a cobalt compound and a compound of the element M to be 1 By producing the positive electrode active material for a battery, excess lithium can be put into the reaction system to increase or adjust the lithium occupancy in the transition metal main layer.

The effect obtained when Li / (Ni + Co + M)> 4 is equivalent to Li / (Ni + Co + M) = 4.
When i / (Ni + Co + M)> 4, Li _X Ni _1-YQ C
o Since only the amount of the lithium compound to be removed other than _{Q MY} O _Z increases, 1 <Li / (N
(i + Co + M) ≦ 4. Li / (Ni + Co +
M) ≦ 1, when the lithium occupation ratio in the transition metal main layer is often less than 0.5%, 1 <
It is effective to set Li / (Ni + Co + M).

In order to form a battery cathode using the cathode active material obtained by the present production method, a mixture of the above-mentioned double oxide powder and a binder powder such as polytetrafluoroethylene is coated on a support such as stainless steel. Crimping, or
A conductive powder such as acetylene black is mixed to impart conductivity to the mixture powder, and a binder powder such as polytetrafluoroethylene is further added as necessary, and the mixture is placed in a metal container. Alternatively, it is formed by means such as compression molding on a support such as stainless steel, or dispersing in a solvent such as an organic solvent to form a slurry and applying the slurry on a metal substrate.

In the battery using the positive electrode active material obtained by the present manufacturing method, when lithium is used as the negative electrode active material, it is formed into a sheet in the same manner as a general lithium battery, and the sheet is made of nickel, stainless steel or the like. A negative electrode is formed by pressure bonding to a conductor net. As the negative electrode active material, a lithium alloy such as a lithium-aluminum alloy can be used in addition to lithium. Further, a negative electrode for a rocking chair battery (lithium ion battery) such as carbon can be used, and lithium ions supplied from the positive electrode by a charging reaction are electrochemically inserted,
A carbon-lithium negative electrode or the like can also be used. The battery can be used as a secondary battery by repeating charging and discharging.

In a battery using the positive electrode active material obtained by this production method, as an electrolytic solution, for example, dimethoxyethane, diethoxyethane, 2-methyltetrahydrofuran, ethylene carbonate, propylene carbonate,
Methyl formate, dimethyl sulfoxide, acetonitrile, butyrolactone, dimethylformamide, dimethyl carbonate, diethyl carbonate, sulfolane,
LiAsF in an organic solvent such as ethyl methyl carbonate
₆ , LiBF ₄ , LiPF ₆ , LiAlCl ₄ , LiClO
A nonaqueous electrolyte solvent in which a Lewis acid such as ₄ is dissolved, a solid electrolyte, a polymer electrolyte, a polymer electrolyte carrying the organic solvent, and the like can be used.

As for other elements such as a structural material such as a separator and a battery case, various conventionally known materials can be used, and there is no particular limitation.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, the production and measurement of the battery were performed in a dry box under an argon atmosphere.

[0031]

EXAMPLE 1 FIG. 1 is a cross-sectional view of a coin-type battery which is a specific example of a battery using a positive electrode active material obtained by a method for producing a positive electrode active material for a lithium battery according to the present invention. Reference numeral 2 denotes a gasket, 3 denotes a positive electrode case, 4 denotes a negative electrode, 5 denotes a separator, and 6 denotes a positive electrode mixture pellet.

As the positive electrode active material, a sample a produced as follows was used. First, lithium hydroxide-hydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and rutile type titanium oxide were prepared by atomic ratio of Li: Ni: Co: Ti = 20: 8:
The mixture was mixed at a ratio of 1: 1 and heat-treated in the air at 500 ° C. for 6 hours and subsequently at 700 ° C. in the air for 24 hours, whereby LiNi _0.8 Co _0.1 Ti _0.1 O ₂ was mixed with other lithium compounds. A mixture was obtained. The mixture is then added to 25
The mixture was washed with water at ℃, and a lithium compound other than LiNi _0.8 Co _0.1 Ti _0.1 O ₂ was dissolved in the aqueous solution and removed by filtration to obtain LiNi _0.8 Co _0.1 Ti _0.1 O ₂ . X
The ray _{diffraction, LiNi 0.8 Co 0.1 Ti 0. 1} O 2 has a layered structure, lithium occupancy in the transition metal-based layer is 4.
It turned out to be 3%. This sample is designated as a.

After vacuum drying this positive electrode active material sample a,
After pulverized to a powder, mixed with a conductive agent (acetylene black) and a binder (polytetrafluoroethylene),
Roll forming, positive electrode mixture pellet 6 (0.5 mm thick,
(Diameter 15 mm).

Next, a metal lithium negative electrode 4 placed under pressure on a stainless steel sealing plate 1 is inserted into a concave portion of a polypropylene gasket 2, and a polypropylene microporous separator 5 is placed on the negative electrode 4. After arranging the positive electrode mixture pellets 6 in this order, injecting and impregnating an appropriate amount of a 1 N solution of LiPF ₆ dissolved in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate as an electrolytic solution,
A coin-type battery having a thickness of 2 mm and a diameter of 23 mm was produced by covering and swaging a stainless steel positive electrode case 3.

The battery prepared as described above, using the sample a as the positive electrode active material, was charged to 4.3 V at a current density of 0.5 mA / cm ² at 25 ° C., and then discharged to 3.0 V. The discharge capacity is shown in the table. Large discharge capacity,
It has the advantage that it can be used as a high energy density battery.

The battery was charged to 4.3 V at a current density of 0.1 mA / cm ² , the battery was disassembled as it was, and a positive electrode mixture pellet containing a positive electrode active material was taken out.
When the endothermic heat generated when heated to 00 degrees was observed using a scanning differential thermal analysis, there was no exothermic heat, and only the endothermic heat was observed. Therefore, a battery using this sample a as a positive electrode active material does not generate heat at a high temperature when fully charged, and can realize a highly safe battery.

A battery using sample a as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery in a wide temperature range.

[0038]

Example 2 In Example 2, a lithium battery was fabricated in the same manner as in Example 1, except that the positive electrode active material sample b obtained by the following manufacturing method was used. First, lithium hydroxide-hydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and rutile-type titanium oxide are mixed in an atomic ratio of Li: Ni: C.
o: Ti = 20: 7: 2: 1, and mixed in air at 500 ° C. for 6 hours, followed by 24 hours at 700 ° C. in air.
LiNi _0.7 Co _0.2 Ti
A mixture of _0.1 O ₂ and other lithium compounds was obtained.

Next, the mixture was washed with water at 25 ° C.
By dissolving a lithium compound other than i _0.7 Co _0.2 Ti _0.1 O ₂ in an aqueous solution and removing by filtration, LiN
to obtain a _{i 0. 7 Co 0.2 Ti 0.1 O} 2. By X-ray diffraction, Li
It has been found that Ni _0.7 Co _0.2 Ti _0.1 O ₂ has a layer structure, and the lithium occupancy in the transition metal main layer is 2.3%. This sample is designated as b.

A battery using the thus prepared sample b as a positive electrode active material was charged to 4.3 V at a current density of 0.5 mA / cm ² at 25 ° C., and then discharged to 3.0 V. The discharge capacity is shown in the table. Large discharge capacity,
It has the advantage that it can be used as a high energy density battery. The battery was charged at a current density of 0.1 mA / cm ² ,
The battery was charged to 4.3 V, the battery was dismantled as it was, the positive electrode mixture pellet containing the positive electrode active material was taken out, and the heat absorption and heat generation when heated to 300 ° C. was observed using scanning differential thermal analysis. No heat absorption was observed. Therefore, a battery using this sample b as a positive electrode active material does not generate heat at a high temperature when fully charged, and can realize a highly safe battery.

A battery using sample b as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery in a wide temperature range.

[0042]

Embodiment 3 In Embodiment 3, the following manufacturing method is used.
Example 1 was the same as Example 1 except that the obtained positive electrode active material sample c was used.
Thus, a lithium battery was produced. First lithium hydroxide
-Hydrate, nickel nitrate hexahydrate and cobalt nitrate hexahydrate
Product and rutile-type titanium oxide in atomic ratio Li: Ni: C
o: Ti = 20: 8: 1: 1
For 6 hours at 500 ° C in air, followed by 24 hours at 800 ° C in air.
Heat treatment for LiNi_0.8Co_0.1Ti
_0.1O_TwoAnd other lithium compounds.
The mixture is then washed with water at 25 ° C._0.8Co_0.1
Ti_0.1O_TwoDissolve other lithium compounds in the aqueous solution,
By removal by filtration, LiNi _0.8Co_0.1
Ti_0.1O_TwoI got By X-ray diffraction, LiNi_0.8Co
_0.1Ti_0.1O_TwoHas a layered structure, and the transition metal
The lithium occupancy was found to be 2.0%. This
Let the sample of c be c.

A battery using the thus prepared sample c as a positive electrode active material was charged to 4.3 V at a current density of 0.5 mA / cm ² at 25 ° C., and then discharged to 3.0 V. The discharge capacity is shown in the table. Large discharge capacity,
It has the advantage that it can be used as a high energy density battery.

This battery was charged to 4.3 V at a current density of 0.1 mA / cm ² , the battery was disassembled as it was, and a positive electrode mixture pellet containing a positive electrode active material was taken out.
When the endothermic heat generated when heated to 00 degrees was observed using a scanning differential thermal analysis, there was no exothermic heat, and only the endothermic heat was observed. Therefore, a battery using this sample c as a positive electrode active material does not generate heat at a high temperature when fully charged, and can realize a highly safe battery.

A battery using sample c as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery in a wide temperature range.

[0046]

Embodiment 4 In Embodiment 4, the following manufacturing method is used.
Same as Example 1 except that the obtained positive electrode active material sample d was used.
Thus, a lithium battery was produced. First lithium hydroxide
-Hydrate, nickel nitrate hexahydrate and cobalt nitrate hexahydrate
Product and rutile-type titanium oxide in atomic ratio Li: Ni: C
o: Ti = 40: 17: 2: 1, and mixed.
6 hours at 500 ° C in air, followed by 2 hours at 700 ° C in air
By heat treatment for 4 hours, LiNi_0.85Co_0.10T
i_0.05O_TwoAnd a mixture of other lithium compounds
Was. The mixture is then washed with water at 25 ° C._0.85C
o_0.10Ti_0.05O _TwoOther lithium compounds in aqueous solution
By melting and removing by filtration, LiNi
_0.85Co_0.10Ti_0.05O_TwoI got By X-ray diffraction, L
iNi_0.85Co_0.10Ti_0.05O_TwoHas a layer structure and transitions
The lithium occupancy in the metal main layer is 0.5%.
It turned out. This sample is referred to as d.

A battery using the thus prepared sample d as the positive electrode active material was charged at 25 ° C. at a current density of 0.5 mA / cm ² to 4.3 V, and then discharged to 3.0 V. The discharge capacity is shown in the table. Large discharge capacity,
It has the advantage that it can be used as a high energy density battery.

The battery was charged to 4.3 V at a current density of 0.1 mA / cm ² , the battery was disassembled as it was, and a positive electrode mixture pellet containing a positive electrode active material was taken out.
When the endothermic heat generated by heating to 00 degrees was observed using a scanning differential thermal analysis, a weak endothermic was observed. Therefore, a battery using this sample d as the positive electrode active material has a low possibility of generating heat at a high temperature when fully charged, and can realize a highly safe battery.

A battery using the sample d as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery in a wide temperature range.

In Examples 1 to 4, specific X, Y, Q,
Specific examples of the positive electrode active material for a lithium battery, which is a double oxide given by the composition formula Li _x Ni _1-YQ Co _Q M _Y O _Z having M, specific examples of the production method thereof, and specific examples of the battery using the same Has been shown, but in general, the composition formula Li _X Ni _{1 -YQ} C
o _Q M _Y O _Z (0 ≦ X ≦ 1.1, 0 <Y + Q <0.5, 0
<Y <0.5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2,
M is silicon, titanium, vanadium, chromium, manganese,
Iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, one or more elements including any of lead),
A positive electrode active material for a lithium battery, wherein a lithium occupation ratio in a transition metal main layer in the layer structure is 0.5% or more and 15% or less, and particularly, the element M contains titanium. , And especially Li / (Ni
+ M)> 1 and comprising as said by removing the _{Li X Ni 1-YQ Co Q} M Y O Z other than lithium compound after heat treatment of the mixture by mixing a lithium compound and a nickel compound and a compound of an element M It is characterized by producing a positive electrode active material for a lithium battery, comprising a positive electrode containing the positive electrode active material for a lithium battery produced by the method for producing a positive electrode active material for a lithium battery, particularly the positive electrode active material for a lithium battery. A lithium metal or lithium compound or a negative electrode containing a substance capable of reversibly inserting and removing lithium ions, and having a substance capable of performing movement for performing an electrochemical reaction with the positive electrode and the negative electrode as a lithium ion substance as an electrolyte substance In the case of a lithium battery, it goes without saying that a similar effect is produced.

[0051]

Comparative Example 1 In Comparative Example 1, a lithium battery was fabricated in the same manner as in Example 1, except that a positive electrode active material sample e obtained by the following manufacturing method was used. First, lithium hydroxide-hydrate and nickel nitrate hexahydrate are combined in an atomic ratio of Li: N.
i = 2: 1 and mixed in air at 500 ° C. for 6 hours.
The mixture was subjected to heat treatment at 700 ° C. for 24 hours in the air for 24 hours to obtain a mixture of LiNiO ₂ and other lithium compounds. Next, the mixture was washed with water at 25 ° C.
dissolving lithium compounds other than iNiO ₂ in an aqueous solution,
LiNiO ₂ was obtained by removing by filtration. X-ray diffraction revealed that LiNiO ₂ had a layered structure and the lithium occupancy in the transition metal main layer was 0.0%. This sample is referred to as e.

The sample e thus prepared was used as a positive electrode active material.
0.5 mA / cm ^TwoAt a current density of 4.
Charge to 3V, then discharge to 3.0V
The capacitance is shown in the table.

The battery was charged to 4.3 V at a current density of 0.1 mA / cm ² , the battery was disassembled as it was, a positive electrode mixture pellet containing a positive electrode active material was taken out, and this was heated to 300 ° C. Observation of heat absorption and heat generation at the time of the heat treatment revealed strong heat generation. Therefore, it was found that the battery using this sample e as the positive electrode active material was likely to generate heat at a high temperature when fully charged, and the safety of the battery was low. Compared with this battery, it can be seen that the battery having the positive electrode active material manufactured in Examples of the present invention has higher safety.

A battery using sample e as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It was found that the discharge capacity was small and the characteristics were degraded at 40 ° C. Compared with this battery, it can be seen that the battery having the positive electrode active material manufactured in the example of the present invention has a wider operating temperature range.

[0055]

Comparative Example 2 In Comparative Example 2, a lithium battery was produced in the same manner as in Example 1, except that a positive electrode active material sample f obtained by the following production method was used. First, lithium hydroxide-hydrate, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate are mixed at an atomic ratio of Li: Ni: Co = 20: 9: 1, and 500 ° C. in the atmosphere. By heating at 700 ° C. for 24 hours in the atmosphere for 6 hours, followed by LiN
A mixture of i _0.9 Co _0.1 O ₂ and other lithium compounds was obtained. The mixture is then washed with water at 25 ° C.
_By dissolving lithium compounds other than _0.9 Co _0.1 O ₂ in an aqueous solution and removing them by filtration, LiNi _0.9 C
o _0.1 O ₂ was obtained. By X-ray diffraction, LiNi _0.9 Co _0.1
Has a layer structure, and the lithium occupancy in the transition metal main layer was found to be 0.0%. This sample is designated as f.

The thus prepared sample f was used as a positive electrode active material.
0.5 mA / cm ^TwoAt a current density of 4.
Charge to 3V, then discharge to 3.0V
The capacitance is shown in the table.

The battery was charged to 4.3 V at a current density of 0.1 mA / cm ² , the battery was disassembled as it was, a positive electrode mixture pellet containing a positive electrode active material was taken out, and this was heated to 300 ° C. Observation of heat absorption and heat generation at the time of the heat treatment revealed strong heat generation. Therefore, it was found that the battery using this sample e as the positive electrode active material was likely to generate heat at a high temperature when fully charged, and the safety of the battery was low. Compared with this battery, it can be seen that the battery having the positive electrode active material manufactured in Examples of the present invention has higher safety.

[0058]

Comparative Example 3 In Comparative Example 3, a lithium battery was fabricated in the same manner as in Example 1, except that a sample g of the positive electrode active material obtained by the following manufacturing method was used. First, lithium hydroxide-hydrate, nickel nitrate hexahydrate, and rutile-type titanium oxide are mixed in an atomic ratio of Li: Ni: Ti = 20: 9: 1, and mixed at 500 ° C. in the atmosphere. Heat treatment at 700 ° C. for 24 hours in the air, followed by LiNi
A mixture of _0.9 Ti _0.1 O ₂ and another lithium compound was obtained. The mixture is then washed with water at 25 ° C.
_By dissolving lithium compounds other than _0.9 Ti _0.1 O ₂ in an aqueous solution and removing them by filtration, LiNi _0.9 T
i _0.1 O ₂ was obtained. By X-ray diffraction, LiNi _0.9 Co _0.1
Has a layer structure, and the lithium occupancy in the transition metal main layer was found to be 3.9%. Let this sample be g.

The sample g thus prepared was used as a positive electrode active material.
0.5 mA / cm ^TwoAt a current density of 4.
Charge to 3V, then discharge to 3.0V
The capacitance is shown in the table.

A battery using sample g as a positive electrode active material was
4.3 V at a current density of 0.5 mA / cm ² at 0 ° C.
Until the voltage reached 4.3 V, the current was cut off, and the battery was kept as it was for one week, and then 0.5 mA / cm ²
The discharge capacity at the time of discharging to 3.0 V at the current density shown in FIG. It was found that the discharge capacity was small and the characteristics were degraded at 40 ° C. Compared with this battery, it can be seen that the battery having the positive electrode active material manufactured in the example of the present invention has a wider operating temperature range.

Table

[0062]

As described above, according to the cathode active material for a lithium battery according to the present invention, the method for producing the same, and the lithium battery, a lithium battery having a large discharge capacity, excellent safety, and a wide operating temperature range is realized. It has the advantage that it can be used in various fields including the power supply of various portable electronic devices.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration example of a coin-type battery according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Gasket 3 Positive electrode case 4 Negative electrode 5 Separator 6 Positive electrode mixture pellet

Continued on the front page (72) Inventor Yoji Sakurai 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 5H003 AA02 AA10 BB05 BD00 5H029 AJ03 AJ12 AK03 AL06 AL12 AM03 AM04 AM07 AM11 AM16 BJ03

Claims (5)

[Claims] 1. A composite oxide having a layer structure represented by the following composition formula, wherein a lithium occupancy in a transition metal main layer in the layer structure is 0.5% or more and 15% or less. Positive electrode active material for lithium batteries. The composition formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0 <Y + Q <0.5,0 <Y <0.
5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2, M is silicon,
One or more elements including any of titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, lead) 2. The positive electrode active material for a lithium battery according to claim 1, wherein the element M includes titanium. 3. A positive electrode for a lithium battery, which is a double oxide having a layer structure given by the following composition formula, wherein the lithium occupancy in a transition metal main layer in the layer structure is 0.5% or more and 15% or less. A method for producing an active material, comprising mixing a lithium compound, a nickel compound, a cobalt compound, and a compound of the element M so that the atomic ratio is Li / (Ni + Co + M)> 1, heat treating the mixture, and then subjecting the mixture to Li _x Ni
_1-YQ Co _Q M _Y O method for producing a cathode active material for lithium battery and removing lithium compounds other than _Z. The composition formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0 <Y + Q <0.5,0 <Y <0.
5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2, M is silicon,
One or more elements including any of titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, lead) 4. A positive electrode for a lithium battery, which is a double oxide having a layer structure given by the following composition formula, wherein a lithium occupation ratio of a transition metal main layer in the layer structure is 0.5% or more and 15% or less. A positive electrode containing an active material, and a negative electrode containing a substance capable of reversibly inserting and removing lithium metal or a lithium compound or lithium ion, wherein lithium ions move to perform an electrochemical reaction with the positive electrode and the negative electrode. A lithium battery comprising a substance capable of performing the following as an electrolyte substance. The composition formula _{Li X Ni 1-YQ Co Q} M Y O Z (0 ≦ X ≦ 1.1,0 <Y + Q <0.5,0 <Y <0.
5, 0 <Q <0.5, 1.8 ≦ Z ≦ 2.2, M is silicon,
One or more elements including any of titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, lead) 5. The lithium battery according to claim 4, wherein the positive electrode active material for a lithium battery is manufactured by the method for manufacturing a positive electrode active material for a lithium battery according to claim 3.