JPH10321228A - Positive electrode active material for lithium battery, its manufacture, and lithium battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the discharge capacity and enhance the safety without generating a heat in the full charge of a battery by regulating the lithium occupying ratio in the transition metal main body layer of the layered structure of a positive electrode active material consisting of a composite oxide mainly composed of Li and Ni to a specified value or less. SOLUTION: A positive electrode active material has a composition of a complex oxide represented by the formula Lix Ni1-y My 0z . In the formula, (x), (y), and (z) represent 0$ x<=1.1, 0<=y<=0.5, and 1.8<=z<=2.2, respectively, and M represents a transition metal other than Ni or at least one element selected from elements belonging to the IVB, VB, VIB, and VIIB groups. The Li occupying ratio in the transition metal main body layer in the layefed structure of this composite oxide is limited to less than 0.5%. The element M is selected from silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum and lead.

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, and more particularly to a technique for providing a lithium battery having a large discharge capacity and excellent safety. Things.

[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 US Pat.
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, 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. That is, when the voltage is high, particularly when the battery is fully charged, when the environmental temperature becomes high or when the battery causes an internal short circuit, the battery generates heat, and in extreme cases, smoke or ignition is observed. There was a safety problem.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned current problems and has a large discharge capacity and excellent safety for a lithium battery, a method for producing the same, and a lithium battery using the same. Is to provide.

[0004]

A positive active material according to the present invention in order to achieve the Means for solving the problem] Such object is the composition formula _{Li X Ni 1-Y M Y} O Z (0 ≦ X ≦ 1.1,0 ≦ Y ≦ 0.
5, 1.8 ≦ Z ≦ 2.2, M is a transition metal other than nickel or one or more elements selected from the group consisting of elements belonging to the IVB, VB, VIB, and VIIB groups). The lithium occupancy of the transition metal main layer in the layer structure is 0.5% or more, and in particular, the element M is silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium. , Niobium, molybdenum, ruthenium, palladium,
Tin, tellurium, hafnium, tungsten, iridium,
It is characterized by platinum and lead.

[0005] In atomic ratio Li / (Ni + M)> 1 and so as lithium compound Li after heat treatment of the mixture by mixing a nickel compound and a compound of an element M _X Ni
It is characterized by producing a positive active material for the lithium battery by removing the _1-Y M _Y O _Z other than lithium compounds.

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 produced by the method for producing the positive electrode active material for a lithium battery. It is characterized by having a negative electrode containing a lithium compound and having, as an electrolyte material, a substance capable of performing movement for lithium ions to perform an electrochemical reaction with the positive electrode and the negative electrode.

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. It has been 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 which have a larger discharge capacity than the conventional one and are excellent in safety.

The reason why the method for producing a positive electrode active material for a lithium battery of the present invention can constitute a battery having a larger discharge capacity than the conventional method for producing a positive electrode active material is not completely clear at present, but for example, The following can be considered. That is, the composition formula Li _X Ni _1-Y M _Y O _Z (0 ≦
X ≦ 1.1, 0 ≦ Y ≦ 0.5, 1.8 ≦ Z ≦ 2.2, M
Represents a transition metal other than nickel or a group IVB or VB,
In a complex oxide given by one or more elements selected from the group VIB and the group VIIB), the lithium occupation ratio of the transition metal main layer in the layer structure is 0.5.
%, The nickel, element M, and lithium in the layer structure are free when the environmental temperature is high or the battery is short-circuited under high voltage, particularly when fully charged. Batteries generate heat due to mixing and change to a rock salt structure in which nickel, element M, and lithium are randomly arranged. In extreme cases, smoke or ignition is observed. Is nickel in the layer structure,
This is presumably because the element M and lithium are less likely to be freely mixed, and a change to a rock salt structure in which the element M and lithium are randomly arranged is suppressed.

The lithium occupation ratio in the transition metal main layer may be 0.5% or more, and there is no particular upper limit. However, if it is too high, the capacity characteristics may be reduced.
0% or less. A part of nickel is replaced with a transition metal other than nickel or a group IVB, VB, VIB, or VIIB.
Although it is not always necessary to substitute the element M belonging to the group, the lithium occupancy in the transition metal main layer can be easily increased to 0.5% or more. This is often because these elements M are compounds containing lithium and oxygen,
For example, it is considered that a compound such as Li _P MO _Q (where P and Q are positive numbers) is prepared and solid-dissolved with Li _X NiO _Z to increase the lithium occupancy in the transition metal main layer.

In particular, when the element M is silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum or lead, These become tetravalent cations and easily form a solid solution with Li _x NiO _Z, and can increase or stabilize the lithium occupancy in the transition metal main layer. Particularly, silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, molybdenum, tin, tungsten, and lead, which are relatively rich in resources, are preferable.

Also, a solid solution Li ₂ MO ₃ with stable lithium
From the viewpoint that is known, silicon, titanium, manganese, iron, germanium, zirconium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, iridium, platinum, lead are preferable, and titanium is considered in consideration of resource properties. , Manganese, iron, zirconium, molybdenum, silicon, germanium, tin and lead are particularly preferred. On the other hand, when the content of the element M is high, the capacity characteristics are deteriorated. Therefore, Y corresponding to the substitution amount of the element M is 0 ≦ Y ≦ 0.5.
Must be satisfied, and preferably 0 ≦ Y ≦ 0.3. When 0.5 <Y, there is a problem that the charge / discharge capacity is reduced.

[0012] In atomic ratio Li / (Ni + M)> 1 and so as lithium compound Li after heat treatment of the mixture by mixing a nickel compound and a compound of an element M _X Ni
_{By 1-Y} M _Y O _Z to remove lithium compounds other than to produce a positive active material for the lithium battery, excess lithium placed in the reaction system, and increasing the lithium occupancy in the transition metal-based layer And can be adjusted. L
The effect obtained when i / (Ni + M)> 4 is Li / (Ni +
M) = 4, and when Li / (Ni + M)> 4, the amount of lithium compound other than Li _x Ni _1-Y M _Y O _Z only increases, so from the economic viewpoint, 1 <Li / (Ni
+ M) ≦ 4. When Li / (Ni + M) ≦ 1, the lithium occupation ratio in the transition metal main layer is often less than 0.5%, and the capacitance characteristic is often low, so that 1 <Li / ( Ni + M) is preferred.

When the lithium compound, the nickel compound and the compound of the element M are mixed and the mixture is heat-treated so that the atomic ratio of Li / (Ni + M)> 1, the firing temperature is from 500 ° C. to 1000 ° C., preferably The firing is performed at 650 ° C. to 850 ° C. The atmosphere is preferably in the air or oxygen, and more preferably in the air from an economic viewpoint. Regarding the firing time, if it is short, Li _X N
Synthesis of i _1-Y M _Y O _Z may be incomplete, also optimum time there is longer and so release of oxygen may occur. Although it largely depends on the charged amount, it is desirable that the time is 1 hour or more and 100 hours or less.

At the stage when the firing is completed, Li _x N
i _1-Y M _Y if O _Z other than glue lithium compound is mixed frequently. Although this depends on the starting materials, most of them are formed by reaction of unreacted lithium with the atmosphere, such as lithium oxide, lithium hydroxide or lithium carbonate. These not only do not contribute to the battery reaction, but also dissolve in the electrolyte to adversely affect the battery characteristics. Therefore, it is desirable to remove them.

[0015] As a method for removal may take known methods used for separation and purification of the compounds, Li _X
It is necessary to reduce the effect on _{Ni 1-Y M Y O Z} .
As such a method, there is a washing method utilizing a difference in solubility. In other words, many of the unreacted lithium compounds generated here have a higher solubility in the solvent than Li _x Ni _1-Y M _Y O _Z , and the entire sample is dispersed in the solvent and stirred. the reaction of lithium compounds are dissolved, by a method such as filtration, only _{Li X Ni 1-Y M Y} O Z can be taken out as a solid. As the solvent, high solubility of the unreacted lithium _{compound, Li X Ni 1-Y M} Y O Z things low solubility is desirable, water, organic solvents, including alcohols, acids, alkaline and the like. Water is particularly desirable from an economic viewpoint.

In order to form a battery positive electrode using the positive electrode active material obtained by the present manufacturing 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 this manufacturing method, when lithium is used as the negative electrode active material, it is formed on a sheet similarly to that of 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, or a solid electrolyte 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.

[0020]

EXAMPLES Hereinafter, the method for producing the positive electrode active material for a lithium battery of the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, preparation and measurement of the battery were performed in a dry box under an argon atmosphere.

[0021]

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, 2 mol of lithium hydroxide monohydrate, 0.9 mol of nickel nitrate hexahydrate and 0.1 mol of manganese nitrate hexahydrate (at an atomic ratio of Li: Ni: Mn = 20: 9:
1, Li / (Ni + Mn) = 2) and mix in air.
LiNi _0.9 by heat treatment at 00 ° C. for 10 hours.
A mixture of Mn _0.1 O ₂ and another lithium compound was obtained. Next, 1 liter of water was added to the mixture at 25 ° C. to wash the mixture, a lithium compound other than LiNi _0.9 Mn _0.1 O ₂ was dissolved in the aqueous solution, and the mixture was removed by filtration to remove LiNi _0.9 Mn _0.1 O ₂ . Obtained. X-ray diffraction revealed that LiNi _0.9 Mn _0.1 O ₂ had a layered structure, and the lithium occupancy in the transition metal main layer was 1.0%. 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 negative electrode 4 made of metallic lithium and placed under pressure on a sealing plate 1 made of stainless steel is inserted into a concave portion of a gasket 2 made of polypropylene, 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.

A battery using the thus prepared sample a as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V is shown in the table. It has the advantage that it has a large discharge capacity and 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.
Observation of heat absorption and heating upon heating to 00 degrees revealed no heat generation and only heat absorption. Therefore, even when the battery is fully charged, no heat is generated, and it is clear that a highly safe battery can be realized.

[0027]

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, 2 mol of lithium hydroxide monohydrate, 0.8 mol of nickel nitrate hexahydrate and 0.2 mol of manganese nitrate hexahydrate (atomic ratio of Li: Ni:
Mn = 10: 4: 1, Li / (Ni + Mn) = 2) were mixed and heat-treated at 700 ° C. in the air for 10 hours to obtain a mixture of LiNi _0.8 Mn _0.2 O ₂ and other lithium compounds. Was. Next, 1 liter of water was added to the mixture at 25 ° C. to wash the mixture, and LiNi _0.8 Mn _0.2
Dissolved O ₂ than the lithium compound in an aqueous solution, are removed by filtration, to obtain a LiNi _{0. 8} Mn _0.2 O _2. X-ray diffraction revealed that LiNi _0.9 Mn _0.1 O ₂ had a layer structure, and the lithium occupancy in the transition metal main layer was 6.2%. This sample is designated as b.

A battery using the thus prepared sample b as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V is shown in the table. It has the advantage that it has a large discharge capacity and 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, a positive electrode mixture pellet containing a positive electrode active material was taken out, and this was heated to 300 ° C. Observation of endothermic and exothermic results showed that there was no exotherm, but only endothermic. Therefore, even when the battery is fully charged, no heat is generated, and it is clear that a highly safe battery can be realized.

[0030]

Example 3 In Example 3, a lithium battery was produced in the same manner as in Example 1, except that the sample c of the positive electrode active material obtained by the following manufacturing method was used. First, 2 mol of lithium hydroxide monohydrate, 0.9 mol of nickel nitrate hexahydrate and 0.1 mol of manganese nitrate hexahydrate (at an atomic ratio of Li: Ni:
Ti = 20: 9: 1, Li / (Ni + Mn) = 2) were mixed and heat-treated at 700 ° C. in the air for 10 hours to obtain a mixture of LiNi _0.9 Ti _0.1 O ₂ and other lithium compounds. Was. Next, 1 liter of water was added to the mixture at 25 ° C. to wash the mixture, and LiNi _0.9 Ti _0.1
Dissolved O ₂ than the lithium compound in an aqueous solution, are removed by filtration, to obtain a LiNi _{0. 9} Ti _0.1 O _2. X-ray diffraction revealed that LiNi _0.9 Ti _0.1 O ₂ had a layer structure, and the lithium occupation ratio in the transition metal main layer was 3.9%. This sample is designated as c.

A battery using the thus prepared sample c as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V is shown in the table. It has the advantage that it has a large discharge capacity and 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, a positive electrode mixture pellet containing a positive electrode active material was taken out, and this was heated to 300 ° C. Observation of endothermic and exothermic results showed that there was no exotherm, but only endothermic. Therefore, even when the battery is fully charged, no heat is generated, and it is clear that a highly safe battery can be realized.

[0033]

Example 4 In Example 3, a lithium battery was manufactured in the same manner as in Example 1, except that a sample d of a positive electrode active material obtained by the following manufacturing method was used. First, 1 mol of lithium hydroxide monohydrate, 0.9 mol of nickel nitrate hexahydrate and 0.1 mol of manganese nitrate hexahydrate (at an atomic ratio of Li: Ni:
Ti = 10: 9: 1, Li / (Ni + Mn) = 1) were mixed and heat-treated at 700 ° C. in the air for 10 hours to obtain a mixture of LiNi _0.9 Mn _0.1 O ₂ and other lithium compounds. Was. Next, 1 liter of water was added to the mixture at 25 ° C. to wash the mixture, and LiNi _0.9 Mn _0.1
Dissolved O ₂ than the lithium compound in an aqueous solution, are removed by filtration, to obtain a LiNi _{0. 9} Mn _0.1 O _2. X-ray diffraction revealed that LiNi _0.9 Mn _0.1 O ₂ had a layer structure, and the lithium occupation ratio in the transition metal main layer was 0.5%. This sample is referred to as d.

A battery using the thus prepared sample d as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V is shown in the table. Example 1 has an advantage that it has a large discharge capacity and can be used as a high energy density battery.
It was found that the discharge capacity was slightly smaller than those of the batteries of Nos. 1 to 3.

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 endothermic and exothermic results showed that there was no exotherm, but only endothermic. Therefore, even when the battery is fully charged, no heat is generated, and it is clear that a highly safe battery can be realized.

In Examples 1 to 5, the composition formula Li _X Ni _{1 -Y} M _Y O _Z having specific X, Y and M (0 ≦ X ≦ 1.1, 0
≦ Y ≦ 0.5, 1.8 ≦ Z ≦ 2.2, M is a transition metal other than nickel or a group IVB, VB, VIB, VI
One or more kinds of elements) lithium battery positive electrode active material is a composite oxide given by the manufacturing method thereof selected from the elements belonging to Group IB, and is shown a specific example of the battery using the same, composition formula Li _X Ni _1-Y M _Y O _Z (0 ≦ X ≦ 1.
1, 0 ≦ Y ≦ 0.5, 1.8 ≦ Z ≦ 2.2, where M is a transition metal, an element belonging to the group IVB, VB, VIB, or VIIB), which is a double oxide provided for a lithium battery. Even in other cases of the positive electrode active material and the method for producing the same, and batteries using the same, the lithium occupancy of the transition metal-based layer in the layer structure is characterized by being 0.5% or more, particularly The element M is silicon, titanium, vanadium, chromium, manganese, iron, germanium, zirconium, niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum, lead, and especially Li in atomic ratio. / (Ni + M)> 1 and comprising as a mixture of compounds of the lithium compound and the nickel compound and the element M Li after heat treatment of the mixture _X Ni
_1-Y M _Y O if by removing the lithium compound other than _Z is characterized by producing a positive active material for the lithium battery, it is needless to say that produces a similar effect.

[0037]

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, 1 mol of lithium hydroxide monohydrate and 1.0 mol of nickel nitrate hexahydrate (atomic ratio: Li: Ni = 2: 1, Li / Ni = 2) were mixed at 700 ° C. in the atmosphere. By subjecting the mixture to heat treatment for an hour, a mixture of LiNiO ₂ and another lithium compound was obtained. Next, 1 liter of water was added to the mixture at 25 ° C. to wash the mixture, and a lithium compound other than LiNiO ₂ was dissolved in an aqueous solution and removed by filtration to obtain LiNiO ₂ . By X-ray diffraction, LiNi
O ₂ has a layer structure, and the lithium occupancy in the transition metal main layer was found to be 0.0%. This sample is e
And

A battery using the thus prepared sample e as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V 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 is likely to generate heat 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.

[0040]

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, 2 mol of lithium hydroxide monohydrate, 0.9 mol of nickel nitrate hexahydrate and 0.1 mol of cobalt nitrate hexahydrate (atomic ratio of Li: Ni:
Co = 2: 0.9: 0.1, Li / (Ni + Co) =
2) were mixed, by heat treatment for 10 hours at 700 ° C. in air to obtain a mixture of LiNi _{0. 9} Co _0.1 O ₂ and other lithium compounds. Then add 25
The mixture was washed by adding 1 liter of water
_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
O ₂ has a layer structure, and the lithium occupancy in the transition metal main layer was found to be 0.0%. This sample is called f
And

A battery using the thus prepared sample f as a positive electrode active material was prepared at a current density of 0.5 mA / cm ² .
The discharge capacity when charged to 3V and then discharged to 3.0V 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 is likely to generate heat 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.

[0043]

[0044]

As described above, according to the present invention,
A lithium battery having a large discharge capacity and excellent safety can be realized, and has an advantage that it can be used in various fields including a power source 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

Claims (5)

[Claims] A composition formula Li _x Ni _1-Y M _Y O _Z (0 ≦ X ≦ 1.
1, 0 ≦ Y ≦ 0.5, 1.8 ≦ Z ≦ 2.2, M is a transition metal other than nickel or a group IVB, group VB, VIB
, A complex oxide given by one or more elements selected from elements belonging to Group VIIB and Group VIIB), wherein the lithium occupancy of the transition metal main layer in the layer structure is 0.5% or more. Positive electrode active material for lithium batteries. 2. The method according to claim 1, wherein said element M is silicon, titanium, vanadium,
Chromium, manganese, iron, germanium, zirconium,
Niobium, molybdenum, ruthenium, palladium, tin, tellurium, hafnium, tungsten, iridium, platinum,
The positive electrode active material for a lithium battery according to claim 1, wherein the positive electrode active material is lead. 3. A mixture of a lithium compound, a nickel compound, and a compound of an element M so that the atomic ratio of Li / (Ni + M)> 1 is obtained, and the mixture is heat-treated, and then Li _X Ni _{1 -Y} M
_Y O by removing the _Z other than lithium compounds, method for producing a cathode active material for a lithium battery, characterized in that to produce the _{Li X Ni 1-Y M Y} O Z of Claim 1 Claim 2 wherein. 4. A positive electrode comprising the positive electrode active material for a lithium battery according to claim 1, further comprising a negative electrode comprising lithium metal or a lithium compound, wherein lithium ions undergo an electrochemical reaction with the positive electrode and the negative electrode. A lithium battery comprising, as an electrolyte substance, a substance capable of transferring ions. 5. The positive electrode active material for a lithium battery according to claim 3, wherein
The lithium battery according to claim 4, which is manufactured by the method for manufacturing a positive electrode active material for a lithium battery according to (1).