JPH10144315A - Active material for positive electrode of nonaqueous electrolyte secondary battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide active material for a positive electrode by which discharge capacity and coulomb efficiency can be enhanced and its manufacturing method. SOLUTION: Lithium and cobalt double oxide powder containing boron and magnesium, which complies with a condition of x=0.97-1.005, y=0.01-0.04, z=0.01-0.05 in a formula of Li×Co2 -x-y-zByMgzO2 , and lithium cobalt double oxide powder containing boron, which compiles with a condition of x=0.97-1.005, y=0.01-0.12 in a formula of LixCo2 -x-yByO2 , are synthesized, and the powder synthesized with a specific surface of 0.2-1.1m<2> /g and an average article diameter of 4.0-16μm is used as active material for a positive electrode. A proper method to produce the active material for the positive electrode is that lithium compound, cobalt compound boron compound and magnesium compound are wet ground and blended and after adjusting an average article diameter to not more than 0.1μm it is baked for 6-20 hours at the temperature of 800-950 deg.C in air stream containing oxygen.

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 non-aqueous electrolyte secondary battery using lithium metal, a lithium alloy or carbon as a negative electrode and a method for producing the same. It relates to improvement of characteristics (maintaining high capacity).

[0002]

2. Description of the Related Art In recent years, with the spread of portable devices such as portable telephones and notebook personal computers, development of secondary batteries having a high energy density, small size, light weight and high capacity has been strongly desired. As such a device, there is a lithium ion secondary battery using a lithium metal, a lithium alloy, or carbon for a negative electrode, and research and development have been actively conducted.

[0003] Lithium-cobalt double oxide (LiCoO)
₂ ) Lithium-ion secondary battery using positive electrode active material is 4
Since a high V-class voltage can be obtained, it is expected as a secondary battery having a high energy density, and its practical use is progressing.

[0004] However, a secondary battery using a lithium-cobalt double oxide as a positive electrode active material has low Coulomb efficiency (discharge capacity / charge capacity), discharge capacity (utilization rate of positive electrode active material), and cycle characteristics ( (Maintenance of high capacity) was insufficient.

[0005] The low coulomb efficiency is due to electrode characteristics. Factors include surface properties such as specific surface area and wettability of the active material that affect electrode reactivity at the interface between the positive electrode active material and the electrolyte, and particle shape and particle size that affect the packing density of the active material. The problem of distribution can be cited.

[0006] The reason for the low utilization rate of the positive electrode active material is as follows.
An unreacted cobalt oxide which is difficult to charge and discharge can be included. In order to prevent this problem, Li
A method is adopted in which the / Co ratio is set to 1 or more to perform synthesis.

However, for example, see Japanese Patent Application Laid-Open No. 3-27256.
No. 4 discloses that when synthesis is performed using an excess Li raw material, the lithium-cobalt double oxide crystal is oriented in the [104] plane, so that the development of the [003] plane that contributes to intercalation of lithium ions is suppressed. It has been pointed out that this reduces the lithium ion storage / release performance.

As a result of the development of the lithium-cobalt composite oxide, the addition of boric acid lowers the viscosity of the molten lithium salt at the time of calcination, and the crystal grains of the obtained lithium-cobalt double oxide are increased. And it was found that the crystallinity was improved.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery which can improve the discharge capacity and Coulomb efficiency of a secondary battery using a lithium cobalt double oxide as a raw material. And a method for manufacturing the same.

[0010]

Means for Solving the Problems In the course of research on the positive electrode active material, the present inventors have found that the particle size can be controlled by adding boron to a lithium-cobalt double oxide, and the addition of boron together with magnesium results in a conductive property. Rate can be improved.

That is, the present invention relates to the formula LixCo ₂ -x-y-
x = 0.97~1.005 in zByMgzO _2, y = 0.
A powder of a lithium-cobalt double oxide containing boron and magnesium having a specific surface area of 0.2 to 1.1 m ² / g having a specific surface area of 0.2 to 1.1 m ² / g having a mean surface area of 0.01 to 0.04 and z = 0.01 to 0.05 is obtained. The powder having a particle size of 4.0 to 16 μm is used as a positive electrode active material.

Also, in the formula LixCo ₂ -x-yByO ₂
A powder of a lithium-cobalt double oxide containing boron in which x = 0.97 to 1.005 and y = 0.01 to 0.12 is synthesized, and has a specific surface area of 0.2 to 1.1 m ² / g. The powder having an average particle diameter of 4.0 to 16 μm is used as a positive electrode active material.

A suitable method for preparing the cathode active material of the present invention is to convert a lithium compound, a cobalt compound, a boron compound and a magnesium compound into a compound of the formula LixCo ₂ -x-y-zBy.
X = 0.97 to 1.005, y = 0.0 in MgzO ₂
After wet-pulverizing and mixing so as to be 1 to 0.04 and z = 0.01 to 0.05, and adjusting the average particle diameter to 1.0 μm or less, in an air stream containing oxygen, the temperature is 800 to 950 ° C. At 6
It is characterized by firing for up to 20 hours.

Further, a lithium compound, a cobalt compound and a boron compound are represented by the formula LixCo ₂ -x-yByO ₂
After wet pulverization and mixing so that x = 0.97 to 1.005 and y = 0.01 to 0.12, the average particle diameter is adjusted to 1.0 µm or less, and then the temperature is reduced in a stream containing oxygen. 800-95
Bake at 0 ° C for 6 to 20 hours.

Alternatively, a lithium compound, a cobalt compound and a boron compound are mixed with a Li / Co molar ratio of 0.95.
~ 1.0, the wet pulverization and mixing so that the B / Co molar ratio is 0.01 ~ 0.12, and the average particle diameter of the raw material powder is 1.0
μm or less, the temperature is 750 ° C.
Bake at 950 ° C. for 10 to 20 hours.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As a raw material cobalt compound,
For example, cobalt hydroxide, cobalt carbonate, and cobalt oxide can be used. As the lithium compound, lithium carbonate, lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, or a mixture thereof can be used. Further, as the boron compound, boric anhydride, boric acid and the like can be used. As the magnesium compound, basic magnesium carbonate and magnesium hydroxide can be used.

The above raw materials are prepared by mixing Li / Co in a molar ratio of 0.9.
5 to 1.0, B / Co is mixed to 0.01 to 0.12,
A positive electrode active material with good crystallinity can be obtained by pulverizing in a wet manner and then firing to synthesize. The addition amount of boron which is a feature of the production method of the present invention, x = 0.95 to the composition formula LixCo ₂ -xByO ₂ of lithium cobalt complex oxide
1.0, y = 0.01 to 0.12. More preferably, the value of y is 0.015 or more and 0.09 or less.
If it is less than 0.01, there is no effect of addition and an active material having good crystallinity cannot be obtained. If it exceeds 0.12, the impurity phase (Li ₃ B
Since O ₃ ) is generated, the crystallinity is degraded, and at the same time, the conductivity is also lowered. A decrease in the conductivity of the active material is not preferable because a large amount of an auxiliary agent is required.

Further, the above raw material is represented by the formula LixCo ₂ -xy-zBy
X = 0.97 to 1.005, y = 0.0 in MgzO ₂
1 to 0.04, z = 0.01 to 0.05, mixed and wet pulverized, and then fired to obtain a positive electrode active material with good crystallinity and high conductivity. it can.

In order to obtain a positive electrode active material having a uniform composition,
It is effective to carry out the pulverization and mixing in a wet manner, and it is important to adjust the average particle diameter to 1.0 μm or less.

As a wet pulverization / mixing method, an apparatus such as a ball mill or a bead mill can be used. As a solvent, pure water is preferable, but an alcohol such as ethanol can be used without any problem.

The content of lithium is x = 0.97 to 1.00.
If the ratio is less than 0.97, the reactivity during firing decreases, and a uniform positive electrode active material cannot be obtained. For this reason, the capacity retention of the secondary battery incorporating the positive electrode active material decreases.
On the other hand, if the value exceeds 1.005, excess lithium remains on the particle surface, and moisture absorption and reaction with carbon dioxide in the air are likely to occur, with the result that the positive electrode active material is deactivated.

The content of boron is preferably y = 0.01 to 0.04. If it is less than 0.01, the crystallinity is not sufficiently improved by adding boron. If it exceeds 0.04, magnesium to be added at the same time precipitates, the crystallinity decreases, and the discharge capacity of the secondary battery incorporating the positive electrode active material decreases.

The content of magnesium is z = 0.01-0.
05 is good. If it is less than 0.01, the effect of improving the conductivity is insufficient. If it exceeds 0.05, a different phase is precipitated, and the crystallinity is lowered.

In another embodiment, the raw material is of the formula Li
x = 0.97 to 1.005 in xCo ₂ -x-yByO ₂ , y =
The positive electrode active material having good crystallinity can be obtained by mixing the mixture so as to be 0.01 to 0.12, pulverizing the mixture by a wet method, and baking the mixture. Although the conductivity is slightly inferior to the case where Mg is contained, the addition range of B for controlling particles (improving crystallinity) can be widened.

In order to obtain a positive electrode active material having a uniform composition,
It is effective to carry out the pulverization and mixing in a wet manner, and it is important to adjust the average particle diameter to 1.0 μm or less.

As the wet pulverizing and mixing method, an apparatus such as a ball mill or a bead mill can be used. As the solvent, pure water is preferable, but alcohol such as ethanol can be used without any problem.

The content of lithium is x = 0.97 to 1.00.
If the ratio is less than 0.97, the reactivity during firing decreases, and a uniform positive electrode active material cannot be obtained. For this reason, the capacity retention of the secondary battery incorporating the positive electrode active material decreases.
On the other hand, if the value exceeds 1.005, excess lithium remains on the particle surface, and moisture absorption and reaction with carbon dioxide in the air are likely to occur, with the result that the positive electrode active material is deactivated.

The boron content is preferably y = 0.01 to 0.12. If it is less than 0.01, the crystallinity is not sufficiently improved by adding boron. If it exceeds 0.12, Li ₃ BO ₃ which is an impurity phase is generated, and crystallinity is deteriorated, and at the same time, conductivity is also lowered. A decrease in the conductivity of the positive electrode active material is not preferable because a large amount of an auxiliary material is required.

Regardless of whether magnesium is added or not, the firing temperature is desirably 800 ° C. to 950 ° C. in any case. More preferably, it is 850 ° C or more and 950 ° C or less. When the sintering temperature is lower than 800 ° C., particularly lower than 750 ° C., the obtained positive electrode active material has poor crystallinity and poor electric characteristics, and therefore, the coulomb efficiency of the secondary battery incorporating the positive electrode active material decreases. Resulting in. Since the purpose of the present invention is to obtain a positive electrode active material having excellent crystallinity at lower temperatures,
Although the specification of the upper limit does not make much sense, if the firing temperature is 10
When the temperature exceeds 00 ° C., particularly 1050 ° C., the diffusion of Li intensifies during firing, so that it is difficult to obtain a uniform positive electrode active material, and the capacity retention of a secondary battery incorporating the positive electrode active material deteriorates.

Although there is no problem if the calcination time is long, it is preferably about 6 hours or more and 20 hours or less in view of industrial productivity. If the calcination time is short, the coulomb efficiency and capacity retention of the secondary battery incorporating the positive electrode active material are reduced due to the remaining unreacted substances and a decrease in crystallinity.

The atmosphere during firing may be an air stream containing oxygen, and may be an air stream.

By using the lithium-cobalt double oxide obtained by the present invention as a positive electrode active material, it becomes possible to obtain a secondary battery having a high utilization rate and a high Coulomb efficiency of the positive electrode active material and excellent cycle characteristics.

[0033]

【Example】

(Example 1) Lithium carbonate (Li ₂ CO ₃ : purity 99)
%), Cobalt oxide (Co ₃ O ₄ : Co content 73.3w)
t%), boric acid (H ₃ BO ₃ : purity 99.5%) and basic magnesium carbonate (MgO content: 41.8 wt%)
In the formula LixCo ₂ -xy-zByMgO ₂ , x = 1.0, y
= 0.04 and z = 0.03, respectively.
Using a ball mill container with a capacity of 400 cc, a diameter of 10 mm
75 YSZ (Yttria stabilized zirconia) balls
Using 0 g, 100 cc of distilled water was further added, and the mixture was ground and mixed for 15 hours at a rotation speed of 85 rpm.

The YSZ ball and the slurry are separated using a sieve, preliminarily dried at 80 ° C. for 2 hours, and then dried at 100 ° C.
For 1 hour. The average particle diameter of the obtained mixed powder was 0.65 by a Microtrac particle size distribution analyzer.
μm was confirmed. Using a magnesia setter, synthesis was performed by heating to 850 ° C. at an oxygen flow rate of 0.3 liter / min and a heating rate of 300 ° C./h, and holding for 20 hours.

The composition of the obtained positive electrode active material was determined by ICP analysis and is shown in Table 1.

The conductivity σ shown in Table 2 was determined as follows.
As a binder, 2% by weight of polyflon (F-201) manufactured by Daikin Industries, Ltd. was added to the positive electrode active material, mixed with a mortar, and then subjected to hydrostatic pressing at a pressure of ² t / cm ² at about 5 ×. It was molded into a 5 × 35 mm rectangular parallelepiped. The contact was coated with an In-Ga liquid alloy, the resistance R was determined by a direct current four-terminal method, and calculated by the equation (1).

Σ = (1 / R) (L / S) (1) where S is the cross-sectional area of the sample, and L is the distance between the voltage measuring terminals.

BE by nitrogen adsorption of the obtained positive electrode active material
The specific surface area determined by the T method is 0.62 m ² / g,
The average particle size determined by Microtrack is 10.1μ
m. Table 2 shows the results.

[0039]

[Table 1]

[0040]

[Table 2]

Further, according to the following procedure, the obtained positive electrode active material was incorporated into a secondary battery, and the charge / discharge capacity was measured. 120 mg of positive electrode active material, 22 mg of acetylene black and 8 mg of polytetrafluoroethylene resin (PTFE)
Were mixed, press-molded to a diameter of 11 mm at a pressure of 200 MPa, and dried in a vacuum dryer at 120 ° C. for 12 hours to obtain a positive electrode.

FIG. 1 is a partially cutaway perspective view of a secondary battery incorporating a positive electrode active material according to an embodiment of the present invention.

The positive electrode 5 was assembled into a 2032 type coin battery (also called a button type battery) in a glove box in an Ar atmosphere. The negative electrode 2 has a diameter of 17 mm and a thickness of 1 m
m of lithium metal and 1 mol of LiPF
Ethylene carbonate (EC) with ₆ as supporting salt and 1,
An equal volume mixed solution of 2 dimethoxyethane (DME) was used. As the separator 3, a polyethylene porous film having a thickness of 25 μm was used. Although the electrolytic solution is not shown in the figure, the electrolytic solution exists in a void inside the coin battery. The coin battery is 1
Leave it for about 0 hours, and after the OCV becomes stable,
A charge / discharge test was performed at a cutoff of 4.3 to 3.0 V at mA / cm ² . Table 3 shows the measurement results of the discharge capacity, Coulomb efficiency, and the 100th capacity retention rate at the 1, 50, and 100 times.

[0044]

[Table 3]

Example 2 Lithium carbonate, cobalt oxide, boric acid and basic magnesium carbonate were converted to a compound of the formula LixC
x = 0.98, y = 0.0 in o ₂ -xy-zByMgO ₂
The positive electrode active material was synthesized in the same manner as in Example 1 except that the weighing was performed at 870 ° C. at 15, and z = 0.01. The composition of the analysis result is shown in Table 1, the conductivity σ, the specific surface area and the average particle size are shown in Table 2, and the discharge capacity of the coin battery incorporating the cathode material in the same manner as in Example 1;
Table 3 shows the measurement results of the Coulomb efficiency and the 100th capacity retention ratio.

Example 3 Lithium carbonate, cobalt oxide, boric acid and basic magnesium carbonate were converted to a compound of the formula LixC
x = 1.0 and y = 0.0 in o ₂ -xy-zByMgO ₂
The positive electrode active material was synthesized in the same manner as in Example 1 except that the sintering temperature was set to 920 ° C. and z = 0.05. Table 1 shows the composition of the analysis results,
, Specific surface area, and average particle size are shown in Table 2. Table 3 shows the measurement results of the discharge capacity, the Coulomb efficiency, and the 100th capacity retention rate of the coin battery incorporating the cathode material in the same manner as in Example 1. .

Example 4 Lithium carbonate, cobalt oxide, and boric acid were converted to a compound of the formula LixCo ₂ -x-yByO _{2 where} x =
1.0 and y = 0.08, respectively, and the cathode active material was synthesized in the same manner as in Example 1. Table 1 shows the composition of the analysis results, and Table 2 shows the conductivity σ, specific surface area, and average particle size.
Table 3 shows the measurement results of the discharge capacity, the Coulomb efficiency, and the 100th capacity retention rate of the coin battery incorporating the cathode material in the same manner as in Example 1.

(Comparative Example 1) Lithium carbonate, cobalt oxide and basic magnesium carbonate were converted to the formula LixCo ₂ -x-zMg
A positive electrode active material was synthesized by weighing each of zO _{2 so} that x = 1.0 and z = 0.08, setting the firing temperature to 1000 ° C., and using the other conditions as in Example 1. Table 1 shows the composition of the analysis results, and Table 2 shows the conductivity σ, specific surface area, and average particle size.
Table 3 shows the measurement results of the discharge capacity, the Coulomb efficiency, and the 100th capacity retention rate of the coin battery incorporating the cathode material in the same manner as in Example 1.

Comparative Example 2 Lithium carbonate, cobalt oxide, boric acid and basic magnesium carbonate were converted to a compound of the formula LixC
x = 0.96, y = 0.0 in o ₂ -xy-zByMgO ₂
5, weighed each so that z = 0.03, and
A positive electrode active material was synthesized in the same manner as described above. The composition of the analysis result is shown in Table 1, the electrical conductivity σ, the specific surface area and the average particle diameter are shown in Table 2, and the discharge capacity, Coulomb efficiency and 100 of the coin battery incorporating the positive electrode active material in the same manner as in Example 1 are shown. Table 3 shows the results of the second measurement of the capacity retention ratio.

As is clear from Table 3, when the lithium-cobalt double oxide containing boron and magnesium according to the present invention was used as a positive electrode active material of a secondary battery (Examples 1 to 3).
3), Coulomb efficiency of charge / discharge (discharge capacity / charge capacity),
Both the capacity retention ratio (100th discharge capacity / first discharge capacity) show characteristics superior to the secondary battery using the positive electrode active material of the comparative example.

Further, when the lithium-cobalt double oxide containing boron according to the present invention was used as the positive electrode active material of the secondary battery (Example 4), it was superior to the secondary battery using the positive electrode active material of the comparative example. It shows the characteristic of having a capacity retention ratio.

Although the secondary battery in this embodiment is a button battery using lithium metal as a negative electrode, the use of the positive electrode active material of the present invention is not limited to this.
The present invention can also be used for a secondary battery in which carbon such as carbon fiber or graphite capable of reversibly intercalating Li by a battery reaction is used as a negative electrode.

(Examples 5 to 8 and Comparative Examples 3 and 4) Table 4
As shown in the figure, lithium carbonate (Li ₂ Co ₃ : purity 99)
%), Cobalt oxide (Co ₃ O ₄ : Co content 73 wt%)
%), Boric acid (H ₃ BO _3: Take weighing 99.5%) and pure water 90cc, respectively, using a ball mill container having a capacity of 400 cc, using 750g of YSZ (yttria-stabilized zirconia) balls having a diameter of 10 mm, rotating Speed 85
The mixture was ground and mixed at 15 rpm for 15 hours.

The YSZ ball and the slurry are separated using a sieve, preliminarily dried at 80 ° C. for 3 hours, and then dried at 120 ° C.
For 1 hour. The obtained mixed powder was analyzed by a Microtrac particle size distribution analyzer to have an average particle diameter of 0.65 μm.
m. Using a magnesium setter, the synthesis was performed by heating to 900 ° C. at a heating rate of 300 ° C./h at an oxygen flow rate of 0.3 liter / min and holding for 15 hours.

Table 4 shows the composition of the positive electrode active material obtained,
Shows the blending amount of raw materials.

[0056]

[Table 4]

As a result of XRD measurement, Comparative Example 4 (y = 0.14
Precipitation of Li ₃ BO ₃ was observed in the positive electrode active material of 7).

About 3 g of the positive electrode active material is ground using a mortar,
Polytetrafluoroethylene resin (Daikin Industries, Ltd.)
(F-201) was added at 2 wt% and mixed, and then formed into a rectangular parallelepiped (about 30 × 5 × 5 mm) by a hydrostatic press with a load of 2 tons. The conductivity was measured by a DC four-terminal method. Table 5 shows the conductivity of the obtained positive electrode active material.

[0059]

[Table 5]

As shown in Table 5, it is found that the conductivity decreases as the amount of boron added increases.

A secondary battery was assembled using the obtained positive electrode active material, and the charge / discharge capacity was measured. A positive electrode was prepared by mixing 120 mg of the positive electrode active material, 22 mg of acetylene black, and 8 mg of polytetrafluoroethylene resin (PTFE), and press-molding to a diameter of 11 mm at a pressure of 200 MPa. The produced positive electrode was dried in a vacuum dryer at 120 ° C. overnight, and assembled into a 2032 type coin battery in a glove box under an argon atmosphere. For the negative electrode, lithium metal having a diameter of 17 mm and a thickness of 1 mm was used, and as the electrolytic solution, a mixed solution of equivalent amounts of ethylene carbonate (EC) and diethyl carbonate (PC) using 1 mol of LiPF ₆ as a supporting salt was used. As the separator, a polyethylene porous film having a thickness of 25 μm was used. The coin battery was left for about 10 hours, and after the OCV was stabilized, the cutoff was 4.3 at a current density of 1.0 mA / cm ^2.
The charge and discharge test was performed 100 times at 3.0 V. Table 6 shows the results.

[0062]

[Table 6]

As shown in Examples 5 to 8, it can be seen that the secondary batteries using the positive electrode active material according to the present invention are excellent in both Coulomb efficiency and capacity retention.

(Examples 9 and 10 and Comparative Example 5) 93.3 g of lithium carbonate (Li ₂ Co ₃ ) and cobalt carbonate (Co
₃ O ₄ ) 203.48 g, boric acid (H ₃ BO ₃ ) 4.37 g
Are weighed, and 360 cc of pure water is added thereto.
3650g of YSZ ball of 0mm, capacity 2000
In a cc ball mill container, pulverization and mixing were performed at a rotation speed of 67 rpm for 15 hours.

The YSZ ball mill and the slurry were separated by using a sieve, and were preliminarily dried at 80 ° C. for 3 hours.
Drying was performed at 0 ° C. for 1 hour. The resulting mixed powder was analyzed by a Microtrac particle size distribution analyzer, using an average particle diameter of 0.6 μm.
m.

About 90 g of the mixed powder was heated using a magnesium setter at an oxygen flow rate of 0.3 L / min at a heating rate of 300 ° C./h to the firing temperature shown in Table 7, and held for 10 hours. Synthesis was performed.

At this time, the composition is Li _1.0 Co _1.003 B _0.028
It becomes O ₂ . A charge / discharge test was performed in the same manner as in Example 5.
Table 7 shows the results.

[0068]

[Table 7]

As shown in Table 7, when the positive electrode active material according to the present invention is used in a lithium secondary battery, a secondary battery having high charge / discharge coulomb efficiency and high capacity retention rate can be obtained.

[0070]

The positive electrode active material according to the present invention can be used as a positive electrode active material for a non-aqueous electrolyte secondary battery to improve the discharge capacity (utilization rate of the positive electrode active material) and the Coulomb efficiency of the secondary battery. It is possible to produce a secondary battery having an excellent capacity retention ratio.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view of a 2032 type coin battery used in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode can 2 Lithium metal pellet 3 Separator 4 Gasket 5 Positive electrode pellet 6 Positive electrode can

Claims (5)

[Claims] 1. A powder of a lithium-cobalt double oxide containing boron and magnesium, having a specific surface area of 0.2 to 1.
1 m ² / g, the average particle size is 4.0 to 16 μm, and in the formula Li x Co ₂ -x-y-zByMgO ₂
x = 0.97 to 1.005, y = 0.01 to 0.04, z =
A positive electrode active material for a non-aqueous electrolyte secondary battery, which is 0.01 to 0.05. 2. A lithium compound, a cobalt compound, a boron compound and a magnesium compound having the formula LixCo ₂ -x
X = from .97 to 1.005 in -y-zByMgzO _2, y
= 0.01-0.04, pulverized and mixed in a wet manner so that z = 0.01-0.05, and adjusted to an average particle size of 1.0 μm or less. 800-95
The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the method is calcined at 0 ° C. for 6 to 20 hours. 3. A powder of a lithium-cobalt double oxide containing boron, having a specific surface area of 0.2 to 2.0 m ² / g, an average particle diameter of 4.0 to 16 μm, and a formula L
x = 0.97 to 1.00 in ixCo ₂ −x−yByO ₂
5. A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein y is 0.01 to 0.12. 4. A lithium compound, a cobalt compound and a boron compound having the formula LixCo ₂ -x-yByO _{2 where} x =
0.97 to 1.005, y = 0.01 to 0.12, wet pulverization and mixing to adjust the average particle diameter to 1.0 μm or less, and then, in an oxygen-containing air flow, at a temperature of 800 ~ 95
4. The sintering at 0 DEG C. for 6 to 20 hours.
3. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to item 1. 5. A lithium compound, a cobalt compound and a boron compound having a Li / Co molar ratio of 0.95 to 1.0.
The mixture was wet-pulverized and mixed at a B / Co molar ratio of 0.01 to 0.12 to adjust the average particle diameter to 1.0 μm or less.
A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, characterized by firing for 20 hours.