JPH09259879A - Manufacture of positive electrode active material for lithium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for positive electrode material to realize a lithium battery of a large discharge capacity. SOLUTION: This substance is double oxide expressed by a composition formula of LiXNi1- YMYOZ (0<=X<=1.1, 0<=Y<=0.5, 1.8<=Z<=2.2, M is an element of a transition metal, IIIB group, IVB group, or VB group). In a manufacturing method for this substance, lithium compound, nickel compound, and compound of the element M are mixed to provide an atomic ratio of Li/(Ni+M)>1, and after heat treatment to this mix, lithium compound other than LiXNi1- YMYOZ is cleaned to be eliminated by use of water or solution in which lithium compound is dissolved, where total lithium ion concentration in cleaning liquid is 0.01mol/liter or more, with the cleaning liquid set in such a way that lithium compound other than LiXNi1- YMYOZ in the cleaning liquid is completely dissolved without saturating at a cleaning temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a positive electrode active material for a lithium battery, and more particularly to a method for producing a positive electrode active material for a lithium secondary battery which can be charged and discharged, and particularly provides a battery having a large discharge capacity. The present invention relates to a method for producing a positive electrode active material.

[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 difluride have been proposed for these positive electrode active materials, but they have a drawback that the voltage is as low as about 2 V and the discharge energy is small.

In order to solve this problem, a positive electrode material Li _X Ni _1-Y M _Y O _Z (M is a transition metal, I
IIB group, IVB group, VB group element, 0 ≦ X ≦
1.1, 0 ≦ Y ≦ 0.5) has been developed. Since lithium deficiency is generated during the heat treatment to cause a defect in the structure of these compounds, and the discharge capacity is likely to be reduced, a method of synthesizing a compound having a small number of structural defects is Li / (Ni +
A method may be mentioned in which a lithium compound, a nickel compound and a compound of the element M are mixed so that M)> 1, and the mixture is heat treated.

[0004] However, in this case, since _{Li X Ni 1-Y M Y} O in addition to the _{Z Li X Ni 1-Y M Y} O lithium compound other than _Z are formed as by-products, in order to remove it, Li _X Ni _1-Y M _Y O _Z and Li _X Ni _1-Y M _Y O _Z obtained by heat treatment
A method of washing and removing a mixture of lithium compounds other than the above with water having a high solubility for lithium compounds can be mentioned. However, according to the conventional manufacturing method by washing with water, Li _X N
Not only lithium compounds other than i _1-Y M _Y O _Z , but also the lithium of the target Li _X Ni _1-Y M _Y O _Z is also flushed out, so the X value is far below 1 and usable lithium. There is a problem that the battery having a sufficient discharge capacity cannot be realized due to a decrease in the amount or a defect in the structure.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a positive electrode active material for a lithium battery, which solves the above-mentioned problems of the present situation and realizes a lithium battery having a large discharge capacity.

[0006]

In order to achieve the above object, in the method for producing a positive electrode active material for a lithium battery according to the present invention, 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,
In the method for producing a positive electrode active material for a lithium battery, which is a complex oxide given by IIIB group, IVB group, and VB group elements), a lithium compound and a nickel compound are provided so that Li / (Ni + M)> 1 in atomic ratio. And a compound of the element M are mixed, and the mixture is heat treated, and then Li _X Ni _1-Y M
_When cleaning or removing a lithium compound other than _Y O _Z with water or an aqueous solution in which the lithium compound is dissolved,
The cleaning liquid has a total lithium ion concentration of 0.01 mol / liter, preferably 1 mol / liter or more, and a cleaning liquid at a temperature at which a lithium compound other than Li _X Ni _{1 -Y} M _Y O _Z performs cleaning. It is characterized in that the cleaning solution is adjusted so that it can be completely dissolved without being saturated.

The composition formula Li thus obtained is
_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, IIIB group, IV
A positive electrode active material includes a complex oxide given by a group B or VB group element), and lithium or a material capable of absorbing and releasing lithium is used as a negative electrode active material, and lithium ions are used as the positive electrode active material and the negative electrode active material. A lithium battery having a large discharge capacity can be constructed by using an electrolyte substance as a substance that can move for an electrochemical reaction.

The present invention will be described in more detail.

As a result of earnest search for a method for producing a positive electrode material for a lithium battery having a large discharge capacity, the inventor has found that 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, III
In a method for producing a positive electrode active material for a lithium battery, which is a complex oxide provided by a group B, IVB, or VB group), a lithium compound and a nickel compound are provided so that Li / (Ni + M)> 1 in atomic ratio. And a compound of the element M are mixed, and the mixture is heat-treated, and then a lithium compound other than Li _X Ni _{1 -Y} M _Y O _Z is washed and removed using water or an aqueous solution in which the lithium compound is dissolved as a washing liquid,
The total lithium ion concentration in the cleaning liquid is 0.01 mol / liter or more, preferably 1 mol / liter or more, and at a temperature at which a lithium compound other than Li _X Ni _{1 -Y} M _Y O _Z in the cleaning liquid performs cleaning. By adjusting the cleaning liquid so that it can be completely dissolved without being saturated in the cleaning liquid, it was confirmed that it is possible to produce a positive electrode active material for a lithium battery that can constitute a lithium battery having a larger discharge capacity than before,
With this recognition, the present invention has been completed.

The reason why the method for producing a positive electrode active material for a lithium battery of the present invention can form a battery having a larger discharge capacity than the conventional method for producing a positive electrode active material is not completely clear at present. The following can be considered. That is, 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, an element belonging to the IIIB group, the IVB group, and the VB group)
In the synthesis of, the lithium compound, the nickel compound, and the compound of the element M are mixed so that the atomic ratio of Li / (Ni + M)> 1 is satisfied in order to compensate for the lithium deficiency that tends to occur during the heat treatment, and the mixture is heat-treated, _X Ni _1-Y M
_When the lithium compound other than _Y O _Z is washed and removed with water having a high solubility for the lithium compound, not only the lithium compound other than Li _X Ni _1-Y M _Y O _Z but also the target Li _X Ni _1-Y
Lithium of M _Y O _Z is flowed out, the X value is much less than 1, and a battery with sufficient discharge capacity cannot be realized because Li _X Ni _1-Y M _Y O _Z is converted to water. It is thought that this is because it has the property of acting as a base. That is, it is considered that water acts as an acid, and the lithium of Li _X Ni _1-Y M _Y O _Z is lost by the following acid-base equilibrium.

Li _X Ni _1-Y M _Y O _Z + Q (H ₂ O) = Li _XQ H _Q Ni _1-Y M _Y O _Z + Q (LiOH) (A)

Here, Q is a number satisfying 0≤Q≤X. It is considered that the reaction such as the equation (A) occurs according to the equilibrium constant determined by the temperature. However, when the lithium ion concentration in this cleaning solution is 0.01 mol / liter or more, the equilibrium reaction of the above formula (A) hardly proceeds to the right side, and the target Li _X Ni _1-Y M _Y O _Z It is considered that a battery having a sufficient discharge capacity can be realized because the X value does not greatly fall below 1 because lithium is not discharged.

Further, particularly when the lithium ion concentration in the cleaning liquid is 1 mol / liter or more, the equilibrium reaction of the above formula (A) proceeds almost completely to the left side, so that the X value becomes extremely close to 1. It is considered that a battery having a particularly large discharge capacity can be realized. When the amount of lithium ions contained in the cleaning liquid is less than 0.01 mol / liter, the equilibrium reaction of the above formula (A) easily proceeds to the right side, and the target lithium Li _X Ni _1-Y M _Y O _Z Therefore, it is considered that the X value is much lower than 1 and a battery having a sufficient discharge capacity cannot be realized.

Also, at the cleaning temperature, Li _X in the cleaning liquid
If lithium compounds other than Ni _{1 -Y} M _Y O _Z are saturated or cannot be dissolved in the cleaning solution at the cleaning temperature, the lithium compounds other than Li _X Ni _1-Y M _Y O _Z are completely dissolved. The lithium compound other than Li _X Ni _1-Y M _Y O _Z is not removed by the above, and the positive electrode contains a lithium compound, so that a battery having a sufficient discharge capacity cannot be realized, and a short circuit easily occurs. Not suitable as it causes problems.

Further, even when the equilibrium of the above formula (A) is tilted to the left side in advance by using an aqueous solution in which a lithium compound is dissolved in water as a cleaning liquid, the desired Li _X N
Since the lithium of i _1-Y M _Y O _Z is not flowed out, the X value does not greatly fall below 1, and a battery having a sufficient discharge capacity can be realized. However, in this case, L that is to be dissolved or washed away with the lithium compound before washing
Since both the lithium compounds other than i _X Ni _1-Y M _Y O _Z are contained in the cleaning liquid, it is necessary to allow both lithium compounds to be completely dissolved in the cleaning liquid at the cleaning temperature without being saturated. is there.

The element M (M is a transition metal, IIIB group,
The elements belonging to the IVB group and the VB group) have a composition formula of Li _X Ni.
The complex oxide given by O _Z (0 ≦ X ≦ 1.1) can be added as a stabilizer, if necessary, and mainly for improving cycle characteristics and the like when used as a battery. Especially when the amount of lithium desorbed from the positive electrode active material during charging increases,
Since the cycle characteristics may deteriorate, the element M can be added for the purpose of limiting the amount of lithium desorbed from the positive electrode active material during charging. Therefore, many elements other than nickel are applicable since M plays an inactive role by reducing the amount of active nickel. Specific examples of M include scandium, titanium, vanadium, chromium, manganese,
Examples thereof include iron, cobalt, copper, yttrium, zirconium, molybdenum, silver, hafnium, tantalum, tungsten, boron, aluminum, gallium, indium, silicon, germanium, tin, lead, phosphorus, antimony and bismuth. Preferred are titanium, vanadium, manganese, cobalt, boron, and aluminum. Here, in order to secure the charge / discharge capacity based on the redox couple of nickel, Y corresponding to the substitution amount of the element M needs to satisfy 0 ≦ Y ≦ 0.5, and preferably 0 ≦ Y ≦ 0.2. Is.
When 0.5 <Y, there arises a problem that the charge / discharge capacity decreases.

To form a battery positive electrode using the positive electrode 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 placed on a support such as stainless steel. , Or by mixing a conductive powder such as acetylene black for imparting conductivity to such a mixture powder, and further adding a binder powder such as polytetrafluoroethylene to this, The mixture is placed in a metal container, pressure-molded on a support such as stainless steel, or dispersed in a solvent such as an organic solvent to form a slurry, which is applied onto 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 put on a sheet like that of a general lithium battery, and the sheet is made of nickel, stainless steel or the like. It is pressure-bonded to the conductor net of to form a negative electrode. 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.

In the battery using the positive electrode active material obtained by the present manufacturing method, as the 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 non-aqueous electrolyte solvent in which a Lewis acid such as ₄ is dissolved, or a solid electrolyte can be used.

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

[0021]

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 addition, in the examples, the production and measurement of the battery were performed in a dry box under an argon atmosphere.

[0022]

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

As the positive electrode active material, a sample a manufactured as follows was used. First, 2 mol of lithium hydroxide monohydrate and 1 mol of nickel nitrate hexahydrate (atomic ratio of Li / Ni = 2)
Were mixed and heat-treated at 700 ° C. for 10 hours in the atmosphere to obtain a mixture of LiNiO ₂ and a lithium compound other than LiNiO ₂ . X-ray diffraction revealed that lithium compounds other than LiNiO ₂ contained LiOH as a main component.

Next, 1 liter of water was added to this 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 a black gray solid sample. By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, the chemical composition formula of this sample was found to be Li _0.99 NiO _1.99 . This sample is designated as a. When the lithium ion concentration in this washing liquid was examined by atomic absorption spectrometry, it was 1 mol / liter. Further, when the washing liquid was concentrated by evaporation, it was found that at 25 ° C., the lithium compound was saturated when the solution amount reached 0.2 liters, and the lithium compound was precipitated when the solution was concentrated further. It was Therefore, it was found that the concentration of the lithium compound during the washing operation at 25 ° C. was less than the saturation concentration.

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, which was placed under pressure on a stainless steel sealing plate 1, was inserted into a recess of a polypropylene gasket 2, and a polypropylene microporous separator 5 was placed on the negative electrode 4. After arranging the positive electrode material mixture pellets 6 in this order and injecting an appropriate amount of a 1N solution of LiPF ₆ dissolved in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate as an electrolytic solution to impregnate it,
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 sample a thus prepared as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery.

Further, this battery was charged and discharged at a charge and discharge current density of 0.5 mA / cm ² under a voltage range regulation of 3.0 V to 4.3 V, and the discharge capacity at the first time and the discharge capacity at the 10th time. Is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

[0029]

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, 0.2 mol of lithium hydroxide monohydrate and 0.1 mol of nickel nitrate hexahydrate (atomic ratio of Li / Ni = 2) were mixed, and 700
LiNiO ₂ and L by heat treatment at ℃ for 10 hours
A mixture with a lithium compound other than iNiO ₂ was obtained. X
By line diffraction, lithium compounds other than LiNiO ₂
It was found that the main component was LiOH.

Next, 10 liters of water at 25 ° C. was added to this mixture to wash the mixture, and a lithium compound other than LiNiO ₂ was dissolved in an aqueous solution and removed by filtration to obtain a black gray solid sample. By examining the lithium content of this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, it was found that the chemical composition formula of this sample was Li _0.97 NiO _1.97 . This sample is designated as b. When the lithium ion concentration in this washing solution was examined by atomic absorption spectrometry, it was 0.01 mol / liter. Further, when this washing solution was concentrated by evaporation, the solution amount was 0.
At 02 liters, the lithium compound saturates,
It was found that the lithium compound was precipitated when the solution was concentrated further. Therefore, it was found that the concentration of the lithium compound during the washing operation at 25 ° C. was less than the saturation concentration.

A battery using the sample b thus prepared as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery.

Further, this battery was charged and discharged at a charge and discharge current density of 0.5 mA / cm ² under a voltage range regulation of 3.0 V to 4.3 V, and the discharge capacity at the first time and the discharge capacity at the 10th time. Is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

[0033]

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 cobalt nitrate hexahydrate (atomic ratio of Li / (Ni + C
o) = 2) and heat treated in air at 700 ° C. for 10 hours to obtain LiNi _0.9 Co _0.1 O ₂ and LiNi
A mixture with a lithium compound other than _0.9 Co _0.1 O ₂ was obtained. X-ray diffraction revealed that lithium compounds other than LiNi _0.9 Co _0.1 O ₂ contained LiOH as a main component.

Next, 1 liter of water was added to this mixture at 25 ° C. to wash the mixture, and a lithium compound other than LiNi _0.9 Co _0.1 O ₂ was dissolved in an aqueous solution and removed by filtration to obtain a black gray solid sample. Got By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel and cobalt contents by optical emission spectroscopy, the chemical composition formula of this sample was Li _0.99 Ni.
It was found to be _0.9 Co _0.1 O ₂ . This sample is designated as c. When the lithium ion concentration in this washing liquid was examined by atomic absorption spectrometry, it was 1 mol / liter. When the washing solution was concentrated by evaporation,
It was found that at 0 ° C., the lithium compound was saturated when the solution volume reached 0.2 liters, and the lithium compound was precipitated when the solution was concentrated further. Therefore, 25
It was found that the concentration of the lithium compound during the washing and removal operation at ℃ was less than the saturation concentration.

A battery using the sample c thus prepared as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery.

Further, this battery was charged and discharged at a charge / discharge current density of 0.5 mA / cm ² in a voltage range regulation of 3.0 V to 4.3 V, and the first discharge capacity and the 10th discharge capacity. Is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

[0037]

Example 4 In Example 4, a lithium battery was manufactured in the same manner as in Example 1 except that the sample d of the positive electrode active material obtained by the following manufacturing method was used. First, 2 mol of lithium hydroxide monohydrate and 1 mol of nickel nitrate hexahydrate (atomic ratio of Li / Ni = 2) were mixed, and the mixture was mixed in air at 700 ° C. for 10 minutes.
LiNiO ₂ and LiNiO ₂ by heat treatment for a time
A mixture with other lithium compounds was obtained. X-ray diffraction revealed that lithium compounds other than LiNiO ₂ contained LiOH as a main component. Then add 50 to this mixture.
C., wash the mixture with the addition of 0.25 liters of water, L
Dissolve a lithium compound other than iNiO ₂ in an aqueous solution,
A black gray solid sample was obtained by removal by filtration. By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, the chemical composition formula of this sample was Li _1.00 NiO.
It turned out to be _2.00 . This sample is referred to as d. When the lithium ion concentration in this washing solution was examined by atomic absorption spectrometry, it was 4 mol / liter. Further, when the washing solution was concentrated by evaporation, it was found that at 50 ° C., the lithium compound was saturated when the solution amount reached 0.20 liters, and the lithium compound was precipitated when the solution was concentrated further. It was Therefore, it was found that the concentration of the lithium compound during the washing operation at 50 ° C. was less than the saturation concentration.

A battery using the thus prepared sample d as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. It has the advantage that it has a large discharge capacity and can be used as a high energy density battery.

Further, this battery was charged and discharged at a charge and discharge current density of 0.5 mA / cm ² under a voltage range regulation of 3.0 V to 4.3 V, and the first discharge capacity and the 10th discharge capacity. Is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

[0040]

Example 5 In Example 5, a lithium battery was manufactured in the same manner as in Example 1 except that the positive electrode active material sample e obtained by the following manufacturing method was used. First, 0.02 mol of lithium hydroxide monohydrate and 0.01 mol of nickel nitrate hexahydrate
Molar mixture (atomic ratio of Li / Ni = 2) was mixed,
By heat treating at 00 ° C. for 10 hours, LiNiO ₂
And a lithium compound other than LiNiO ₂ was obtained. X-ray diffraction revealed that lithium compounds other than LiNiO ₂ contained LiOH as a main component.

Next, 10 mol of lithium hydroxide monohydrate and 10 liters of water at 25 ° C. are added to this mixture to wash the mixture, and lithium compounds other than LiNiO ₂ are dissolved in an aqueous solution and removed by filtration. A black gray solid sample was obtained. By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, the chemical analysis value of this sample was Li.
It was found to be _0.99 NiO _1.99 . This sample is referred to as e. When the lithium ion concentration in this washing liquid was examined by atomic absorption spectrometry, it was 1 mol / liter. When the washing solution was concentrated by evaporation,
At ° C, it was found that the lithium compound was saturated when the solution amount became 2 liters, and the lithium compound was precipitated when the solution was concentrated further. Therefore, it was found that the concentration of the lithium compound during the washing operation at 25 ° C. was less than the saturation concentration.

Sample d thus prepared was used as a positive electrode active material.
Quality battery, 0.5mA / cm ^TwoWith the current density of
When charging to 4.3V and then discharging to 3.0V
The discharge capacity is shown in the table. Large discharge capacity and high energy
It has the advantage that it can be used as a density battery.

Further, this battery was charged and discharged at a charge / discharge current density of 0.5 mA / cm ² within a voltage range regulation of 3.0 V to 4.3 V, and the first discharge capacity and the 10th discharge capacity. Is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

In Examples 1 to 5, the composition formula Li _X Ni _1-Y M _Y O _Z (0 ≦ X ≦ 1.1, 0) having specific X, Y and M was used.
≦ Y ≦ 0.5, 1.8 ≦ Z ≦ 2.2, M is a transition metal, I
A specific production example of the positive electrode active material for a lithium battery, which is a complex oxide given by the IIB group, the IVB group, and the VB group) is shown. 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, a compound belonging to IIIB group, IVB group, and VB group), which is a complex oxide provided by a positive electrode active material for a lithium battery.
A lithium compound, a nickel compound, and a compound of the element M are mixed so that i / (Ni + M)> 1, and the mixture is heat-treated, and then a lithium compound other than Li _X Ni _1-Y M _Y O _{Z is} added to water or a lithium compound. In the case of removing by washing with an aqueous solution in which is dissolved, the total lithium ion concentration in the washing liquid is 0.01 mol / liter, preferably 1 mol / liter or more, and Li _X Ni _1-Y M _Y O in the washing liquid is _Z
Needless to say, when the cleaning liquid is prepared so that the other lithium compounds are not saturated in the cleaning liquid at the cleaning temperature and can be completely dissolved in the cleaning liquid, the same effect is produced.

[0045]

Comparative Example 1 In Comparative Example 1, the following manufacturing method is used.
The same as in Example 1 except that the obtained positive electrode active material sample f was used.
Thus, a lithium battery was produced. First lithium hydroxide
Monohydrate 0.02 mol and nickel nitrate hexahydrate 0.01
Molar mixture (atomic ratio of Li / Ni = 2) was mixed,
By heat treatment at 00 ° C. for 10 hours, LiNiO 2 _Two
And LiNiO_TwoTo obtain a mixture with a lithium compound other than
Was. By X-ray diffraction, LiNiO_TwoOther than lithium compounds
It was found that the product had LiOH as a main component.

Next, 10 liters of water at 25 ° C. was added to this mixture to wash the mixture, and a lithium compound other than LiNiO ₂ was dissolved in an aqueous solution and removed by filtration to obtain a black gray solid sample. By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, it was found that the chemical analysis value of this sample was Li _0.93 NiO _1.93 . Let this sample be f. When the lithium ion concentration in this cleaning liquid was examined by atomic absorption spectrometry, it was 0.001.
Mol / l.

A battery using the thus-prepared sample e as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. As 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 large discharge capacity.

[0048]

Comparative Example 2 In Comparative Example 2, a lithium battery was produced in the same manner as in Example 1 except that Sample g of the positive electrode active material obtained by the following manufacturing method was used. First, 2 mol of lithium hydroxide monohydrate and 1 mol of nickel nitrate hexahydrate (atomic ratio of Li / Ni = 2) were mixed, and the mixture was mixed in air at 700 ° C. for 10 minutes.
LiNiO ₂ and LiNiO ₂ by heat treatment for a time
A mixture with other lithium compounds was obtained. X-ray diffraction revealed that lithium compounds other than LiNiO ₂ contained LiOH as a main component.

Next, 1 liter of water was added to this 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, and the obtained black gray solid sample was further added once again. At 25 ° C., 1 liter of water was added for washing, and the washing liquid was removed by filtration to obtain a black gray solid sample. By examining the lithium content in this solid sample by atomic absorption spectrometry and the nickel content by optical emission spectroscopy, it was found that the chemical analysis value of this sample was Li _0.93 NiO _1.93 . Let this sample be g. When the lithium ion concentration in the second cleaning liquid was examined by atomic-grade optical analysis,
It was 0.001 mol / liter.

A battery using the thus prepared sample f as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
The table shows the discharge capacities when the battery was charged to 4.3V and then discharged to 3.0V. As 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 large discharge capacity.

[0051]

Comparative Example 3 In Comparative Example 3, a lithium battery was manufactured in the same manner as in Example 1 except that the positive electrode active material sample h obtained by the following manufacturing method was used. First, 2 mol of lithium hydroxide monohydrate and 1 mol of nickel nitrate hexahydrate (atomic ratio of Li / Ni = 2) were mixed, and the mixture was mixed in air at 700 ° C. for 10 minutes.
LiNiO ₂ and LiNiO ₂ by heat treatment for a time
A mixture with other lithium compounds was obtained. X-ray diffraction revealed that lithium compounds other than LiNiO ₂ contained LiOH as a main component.

Next, 10 liters of water at 25 ° C. was added to this mixture to wash the mixture. However, the lithium compounds other than LiNiO ₂ could not be completely dissolved in the aqueous solution, and the lithium compound during the washing and removal work at 25 ° C. It was found that the concentration exceeded the saturation concentration. The solution was filtered and the solid obtained was a mixture sample of LiNiO ₂ and a lithium compound other than LiNiO ₂ . By X-ray diffraction, LiNiO
It was found that lithium compounds other than ₂ have LiOH as a main component. This sample is designated as h.

A battery using the thus prepared sample g as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
When the battery was charged to 4.3 V, a short circuit occurred, and subsequent charging / discharging was impossible. As 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 large discharge capacity.

[0054]

[0055]

As described above, according to the present invention,
A positive electrode active material for a lithium battery, which realizes a lithium battery having a large discharge capacity, can be manufactured, and it has an advantage that it can be used in various fields including a power source for various portable electronic devices.

[Brief description of drawings]

FIG. 1 is an abandoned diagram showing a configuration example of a coin 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 Front Page (72) Inventor Junichi Yamaki 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation

Claims (2)

[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, an element belonging to the IIIB group, the IVB group, and the VB group) and is a positive electrode active material for a lithium battery. In the method for producing a substance, a lithium compound, a nickel compound, and a compound of the element M are mixed so that the atomic ratio is Li / (Ni + M)> 1, and the mixture is heat-treated, and then Li _X N
When a lithium compound other than i _{1 -Y} M _Y O _Z is washed and removed using water or an aqueous solution in which the lithium compound is dissolved as a washing liquid, the total lithium ion concentration in the washing liquid is 0.01 mol / liter or more, And Li _X Ni _1-Y in the cleaning liquid
A method for producing a positive electrode active material for a lithium battery, characterized in that the cleaning liquid is adjusted so that a lithium compound other than M _Y O _Z can be completely dissolved in the cleaning liquid at a cleaning temperature without being saturated. 2. The method for producing a positive electrode active material for a lithium battery according to claim 1, wherein the concentration of lithium ions in the cleaning liquid is 1 mol / liter or more.