JP2002037629A - Lithium content cobalt compounded oxide and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve overcharging resistance which is a disadvantage of a conventional lithium cobalate (LiCoO2) when used as a lithium ion secondary cell and also to make it possible to improve cell capacity. SOLUTION: This lithium content cobalt compounded oxide is represented by the following formula: LiaMbNicCo(1-b-c)O2 (Wherein, M is represented by at least one kind of element selected from Ti, Ga, Zr, Cr, Al, Cu, Zn, and a, b, c, are each represented by 1.00 <=a<=1.03, 0.0003<=b<=0.015, 0<=c<=0.3). In this lithium content cobalt compounded oxide, a lithium compound is mixed with a cobalt compound with the mole ratio of lithium/cobalt within the range of 1.03-1.25 and this mixture is mixed with at least one kind of element selected from Ti, Ga, Zr, Cr, Al, Cu, Zn, and is heat-treated within the range of 800-1050<=, and thereafter the mole ratio of lithium/cobalt is made to show<=1.00<=1.03.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a lithium-containing cobalt composite oxide for a lithium ion secondary battery and a method for producing the same.

[0002] In recent years, lithium ion secondary batteries using lithium cobalt oxide as the active material for the positive electrode have been used as power sources for various electronic devices. In order to reduce the size and weight of electronic devices, they are extremely useful as power supplies for these electronic devices. There is a demand for higher capacity and longer life as batteries. The present invention relates to a lithium-containing cobalt composite oxide and a method for producing the same.

[PRIOR ART] Lithium cobaltate (Li)
CoO ₂ ) is widely used as a positive electrode active material of a lithium ion secondary battery, but at a charge voltage of 4.2 V or more as a lithium ion secondary battery in combination with a negative electrode using a carbonaceous material as an active material, Repeated charging / discharging causes the capacity to drop significantly, the gas pressure in the battery to rise with the decomposition of the electrolyte, causing liquid leakage or opening the safety valve. A strict voltage control electronic circuit is required, and there has been a difficulty in making the power supply of an electronic device expensive.

[0004] The present invention is to improve the overcharge resistance as a lithium ion secondary battery, which is a disadvantage of conventional lithium cobalt oxide (LiCoO ₂ ), and to improve the battery capacity. An object of the present invention is to provide a lithium-containing cobalt composite oxide capable of improving safety, improving capacity, and extending service life by improving overcharge resistance, and establishing a manufacturing method thereof.

[Means for Solving the Problems] As a result of various studies on the above-mentioned problems, the present inventors have found that a small amount of a compound of a specific metal species is used in lithium cobalt oxide to form a conventional lithium cobalt oxide. (LiCo
By improving the overcharge resistance as a lithium ion secondary battery, which is a drawback of O ₂ ), and improving the battery capacity, it is possible to improve the safety, increase the capacity, and increase the length by improving the overcharge resistance. The present inventors have found a lithium-containing cobalt composite oxide having a prolonged life and a method for producing the same, and have completed the present invention.

[Embodiment of the Invention] The present invention will be specifically described below. That is, the present invention provides _a compound of the general formula: Li _a M _{b
Ni c Co (1-b-} c) O 2 ( where M is, Ti, G
a, Zr, Cr, Al, Cu, Zn represents at least one selected from the group, a, b, and c each represent 1.00
≦ a ≦ 1.03, 0.0003 ≦ b ≦ 0.015, 0 ≦
represents a number of c ≦ 0.30. ) Is a lithium-containing cobalt composite oxide, wherein lithium carbonate,
At least one lithium compound selected from lithium hydroxide and lithium acetate and at least one cobalt compound selected from tricobalt tetroxide, cobalt hydroxide and cobalt carbonate have a molar ratio of lithium / cobalt of 1.03.
~ 1.25 and mixed in advance in a temperature range of 900 ° C ~ 1050 ° C, and then pulverized.
A mixture of at least one selected from the group consisting of acetates, nitrates, sulfates, carbonates, hydroxides and oxides of Al, Ti, Ga, Zr, Cu and Zn is mixed and heated at a temperature in the range of 800C to 1050C. After the treatment, excess lithium is extracted and removed with distilled water, deionized water, or the like so that the molar ratio of lithium / cobalt is 1.00 or more and 1.03, and the temperature is set to 100 ° C. to 100 ° C.
A method for producing a lithium-containing cobalt composite oxide, which comprises heating to 150 ° C. or further to 800 ° C. to 900 ° C. and drying by heating.

[0007] The lithium-containing cobalt composite oxide of the present invention is prepared in advance by using Li having a median particle diameter of 6 to 20 µm.
_{1 + x} CoO ₂ (where x is 0.03 ≦ x ≦ 0.25
Represents the number of ), Ti, Ga, Zr, C
r, Al, Cu, a mixture of at least one selected from the group consisting of acetate, nitrate, sulfate, carbonate, hydroxide, and oxide of Zn, and heat-treated in a range of 800 ° C to 1000 ° C, Remove excess lithium with distilled water, deionized water, etc.
Extraction and removal so that the molar ratio with cobalt becomes 1.00 or more and 1.03, followed by drying by heating, the presence of the metal near the particle surface layer allows the conventional pure Li
A behavior different from that of CoO ₂ can be exhibited.

[0008] Cobalt atoms are substituted by the above-mentioned foreign metal except nickel in the range of 1.5 mol% or less of 1 atom. If it exceeds 1.5 mol%, the discharge capacity is remarkably reduced, which is not preferable. If the molar ratio of lithium / cobalt is less than 1.00, the discharge capacity is low, and the cycle life becomes poor when charging and discharging are repeated. Also 1.
If it exceeds 03, when it is stored for a long time under normal humidity and temperature environment as a positive electrode, alkali corrosion occurs on the aluminum foil,
In addition, the current efficiency during charging is lowered, which is not preferable.
In addition, when the above-mentioned foreign metal compound is added during the production of lithium cobaltate in advance, particle diameter enlargement is suppressed, and preferable enlarged particles are not obtained.Thus, an object excellent in overcharge resistance, which is the object of the present invention, is obtained. hard. In the conventional cobalt lithium oxide, when charging is repeated at a voltage of 4.20 V or more with respect to the lithium metal electrode, the discharge capacity is significantly reduced,
Cycle life is shortened, and as a lithium ion secondary battery using a carbonaceous material for the negative electrode, gas is generated by decomposition of the electrolyte, the pressure inside the battery can rises, and a safety valve for releasing pressure and a rupture disk are released. However, it is necessary to use an expensive electronic circuit incorporating a strict charge voltage monitoring and control mechanism, and the disadvantage is that the power supply cost is high in spite of the positive electrode active material that can reduce the weight and size of the battery.
According to the present invention, a stable discharge capacity can be maintained even when charging is repeatedly performed at a voltage of 4.30 V with respect to a lithium metal electrode, and a stable discharge capacity can be obtained only by charging at 4.20 V or less. With lithium cobaltate, a high capacity that cannot be attained can be exhibited. However, the above-mentioned different metals other than nickel are added within a range that does not impair the characteristics of the positive electrode of the present invention. That is, for Cu and Zn, respectively.
Even if 05 mol% or more is replaced with a cobalt atom, gas is more likely to be generated by charging at 4.3 V than unadded cobalt lithium oxide, so that it is limited to less than 0.05 mol%. In the case of Ga, Zr, Cr, and Al, the difference between Cu and Zn is less than 0.05 mol% in the range of 1.5 mol% or less of cobalt atoms in one.
Ordinary tricobalt tetroxide contains only 0.030 mol% or less of the above-mentioned foreign metal with respect to cobalt, and forms acetate, nitrate, sulfate, carbonate, hydroxide and oxide of the metal. By adding the above-mentioned metal remaining in the recovered metal cobalt in a trace amount to the cobalt as at least one type of cobalt compound selected from tricobalt tetroxide, cobalt hydroxide, and cobalt carbonate, the content is kept below the above range for cobalt. Manufactured. The molar ratio of lithium / cobalt was mixed in the range of 1.03 to 1.25, and 900 ° C to 10 ° C.
When the heat treatment is performed in advance in the range of 50 ° C., an excess amount of the metal inhibits an increase in the particle size to be generated, so that the total amount of the metal species exceeds the above range to avoid mixing of the metal species as an impurity. There is a need.

The positive electrode using the lithium-containing cobalt composite oxide of the present invention is a lithium-containing cobalt composite oxide 8
8 to 96% by weight, 3 to 6% by weight of a conductive auxiliary such as graphite powder and acetylene black, and polyvinylidene fluoride (P
VDF), terpolymer of propylene, vinylidene fluoride and tetrafluoroethylene, terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, terpolymer of ethylene, propylene and ethylidene norbornene (EPDM), carboxy-modified styrene-butadiene copolymer, carboxy-modified hydrogenated styrene-butadiene copolymer, carboxymethylcellulose, modified carboxy-modified polyacrylate, carboxy-modified polymethacrylate, ethylene-tetrafluoroethylene copolymer An organic solvent dispersion or an aqueous dispersion comprising 1 to 6% by weight of a binder such as polytetrafluoroethylene (PTFE) or the like is used for degreased aluminum foil (thickness 10 to 20 μm) or laser, punch, electrolytic corrosion, and acid treatment. Yo The apertures aluminum, coating and drying, is obtained by a high density by pressing (pressurization) if necessary.

The negative electrode for the positive electrode of the present invention may be made of lithium metal foil, lithium alloy foil, granular or polygonal natural graphite, fibrous, spherical, particulate, or polygonal artificial graphite, or coke of at least one of the above graphites. At least one carbonaceous material selected from the group consisting of carbonaceous materials obtained from multi-layered carbonaceous materials, coke, and organic polymer materials coated with carbonaceous materials using benzene, toluene, benzpyrene, acenaphthene, etc. 88 to 98% by weight With polyvinylidene fluoride (PVDF), terpolymer of propylene, vinylidene fluoride and tetrafluoroethylene, terpolymer of ethylene, propylene and ethylidene norbornene (EPDM), carboxy-modified styrene butadiene copolymer, Carboxy-modified hydrogenated styrene butadiene copolymer, An organic solvent dispersion or an aqueous dispersion comprising 2 to 6% by weight of a binder such as cellulose, modified carboxy-modified polyacrylate, carboxy-modified polymethacrylate, etc., is prepared and degreased rolled copper foil, electrolytic copper foil ( 7-16 μm) or laser,
It is coated and dried on copper that has been opened by punching, electrolytic corrosion, acid treatment, and sintering of copper fine powder, and if necessary, pressed (pressurized) to obtain a high density. The median particle diameter of the carbonaceous material is in the range of 5 to 30 μm, and is preferable in terms of enhancing the safety and the capacity of the battery.
It is in the range of 30 μm. Further, as long as the safety of the battery is not impaired, tin, silicon, boron and the like can be contained in the carbonaceous material.

The electrolyte used in the present invention contains, as an aprotic organic solvent, for example, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate,
Carbonates such as ethylidene carbonate, lactones such as γ-butyrolactone and ε-caprolactone, esters such as methyl formate, ethyl formate, methyl acetate and ethyl acetate, 1,2-dimethoxymethane and 1,2-diethoxy A mixture of one or more of ethers such as methane, 1,2-diethoxyethane and diglyme, nitriles such as acetonitrile and propionitrile, and heterocyclic compounds containing sulfur and / or nitrogen. Can be used. As the electrolyte, LiPF ₆ , LiB
F ₄ , (CF ₃ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) ₂
Any one of lithium salts such as CLi or a mixture of two or more thereof can be used.

The separator used in the present invention includes a polyethylene microporous membrane, a polypropylene microporous membrane, a polyvinylidene fluoride microporous membrane, a partially crosslinked polyacrylonitrile, a crosslinked polyacrylic ester, and a propylene-fluoride supported on ultrafine cellulose fiber paper. A microporous membrane of vinylidene fluoride-tetrafluoroethylene terpolymer can be used.

The positive electrode using the lithium-containing cobalt composite oxide of the present invention and the above-mentioned negative electrode face each other with the above-mentioned separator interposed therebetween, spirally wound, placed in a cylindrical can, injected with the electrolytic solution, and sealed. Alternatively, the separator is wound in an elliptical or elliptical shape, or the positive electrode and the negative electrode are laminated with the separator, placed in a square can or an oblong can, and the electrolyte is injected and sealed. Furthermore, the above-mentioned elliptical roll,
The elliptical wound material and the laminate can be sealed by injecting the electrolytic solution into a laminated film having an inner layer made of a polyethylene or polypropylene film, an intermediate layer made of an aluminum foil, and a surface layer made of a nylon or polyester film.
By changing the number of windings or the number of laminations, it is also possible to form a thin sheet battery.

EXAMPLES The present invention will be described in detail with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

The discharge capacity was measured by using a lithium metal foil surface-treated with carbon dioxide gas as a negative electrode, and using 1 M LiPF ₆ of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) as a negative electrode. Using an electrolyte having a volume ratio of 1: 2: 2 with respect to (1) and (2) for 2 hours at 200 ° C. under reduced pressure, and using a glass filter GA100 made by Toyo Roshi Kaisha as a separator, charge / discharge evaluation is performed with a screw cell. Powder of lithium-containing cobalt composite oxide or lithium cobaltate (90.
5 parts) and graphite powder (KS-
6, 3.0 parts, Nippon Graphite LB300H, 2.5 parts) and then N-methylpyrrolidone (1000 ppm maleic anhydride added to PVDF with PVDF1300 (4.0 parts) manufactured by Kureha as a binder). NMP) solution (solid content 65-68%), applied to one side of a 15 μm double-sided glossy aluminum foil made by Mitsubishi Aluminum Co., Ltd., dried at 150 ° C. within 1 minute, and further heated at the same temperature for 2-3 minutes. Blow hot air. After cooling, the electrode was cut into an electrode having a predetermined size, and further placed in a glass tube oven GTO350 manufactured by Shibata Corporation at 130 ° C. for 3 hours for 0.1 mm.
Dry under Hg vacuum and incorporate as positive electrode in a screw cell in a stream of dry argon gas. Approximately 30 minutes after the addition of the electrolyte, 4.30 V with respect to lithium potential 0 V
Charge at a constant current density of 0.2 mA / cm ² until 4.3
And held for three hours in a constant voltage further 4.30V after reaching to 0V, and a constant current density of 0.4 mA / cm ² Most After confirming become 0 mA / cm ^2, through a quiescent state for 15 minutes in the current density And after reaching 3.70V, 3.7 more
Hold at 0V for 3 hours. The amount of electricity flowing during that time was divided by the weight of the positive electrode active material in the screw cell, and mAh / g
Is defined as the discharge capacity (A). After a resting state of 15 minutes, the constant current density of 0.4 mA / cm ² was 4.3.
0V, and after reaching 4.30V, the voltage was kept at a constant voltage of 4.30V for 3 hours, and the current density was almost 0 mA /
After confirming become cm ^2, and discharged at a constant current density of 0.4 mA / cm ² through a dormant for 15 minutes, 3.70
After reaching V, it is further held at 3.70 V for 3 hours. The amount of electricity flowing during that time is divided by the weight of the positive electrode active material in the screw cell, and the result is defined as the discharge capacity (B) in units of mAh / g. This charge and discharge are repeated. The capacity retention as a measure of the life as an active material is a percentage of the tenth discharge capacity (B) with respect to the discharge capacity. Similarly, 4.
20V charge / discharge is measured under exactly the same conditions except that 4.30V is set to 4.20V.

Example 1 Tricobalt tetroxide 5.284
kg and 2.872 kg of lithium carbonate are mixed in a 20 L Henschel mixer at a high speed for 1 minute, then at a low speed for 1.0 minute, and then 0.300 kg of deionized water is added under low speed stirring, followed by mixing and stirring for 1 minute. The mixture is heated from room temperature to 960 ° C. at a rate of 150 ° C./hour.
After maintaining at 960 ° C. for 8 hours, the temperature is lowered to 890 ° C. and maintained for 3 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. This calcined product is pulverized with a hammer mill and sieved through a 75 μm mesh sieve to obtain 99% or more of the sieved product (A) (L
i: Co molar ratio is 1.17: 1). 99.91 g of this sieve passed product (A) and 1.4797 g of titanium nitrate
In a lab mixer. 150 per hour
Heat from room temperature to 900 ° C. at a rate of temperature increase of 90 ° C. 900
The temperature is lowered to 850 ° C. for 3 hours, kept at 850 ° C. for 3.0 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. Five times the volume of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, and then centrifugally dehydrated. To the dehydrated product, 5 times the amount of deionized water is newly added, well dispersed, and after vigorous stirring for 30 minutes, centrifugally dehydrated. A new 5 times volume of deionized water is added thereto, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. After drying this at 150 ° C., 15
Heat from room temperature to 850 at 0 ° C. ramp rate. 850
After maintaining at 2.0 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. The product is passed through a sieve with a mesh size of 75 μm to obtain a sieve-passed product (B). The composition determined by the ICP method of the sieved product (B) is Li _1.01 Ti _0.005 Co
A _0.995 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Example 2 99.91 g of the product (A) passed through the sieve of Example 1 and 0.790 of chromic monooxalate monohydrate
Mix 2 gg in a lab mixer. This is heated from room temperature to 900 ° C. at a rate of 150 ° C./hour.
After maintaining at 900 ° C. for 3 hours, the temperature is lowered to 850 ° C. and maintained for 3.0 hours, and then cooled to room temperature at a cooling rate of about 150 ° C.
Five times the volume of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, and then centrifugally dehydrated. To the dehydrated product, 5 times the amount of deionized water is newly added, well dispersed, and after vigorous stirring for 30 minutes, centrifugally dehydrated. A new 5 times volume of deionized water is added thereto, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. After drying at 150 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour.
After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. The product is passed through a sieve of 75 μm mesh to obtain a sieve-passed product (C). I of this sifted goods (C)
The composition determined by the CP method is Li _1.01 Cr _0.006 C
a o _0.995 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

[Embodiment 3] Cu, Zn with respect to cobalt
Was mixed with a lab mixer after mixing 1.761 kg of tricobalt tetroxide (recovered product) containing 0.005 mol% and 0.002 mol% of lithium carbonate, respectively, and 0.100 kg of deionized water was added with stirring. After mixing, mix for an additional minute. The mixture is heated from room temperature to 900 ° C. at a rate of 150 ° C./hour. After holding at 900 ° C for 3 hours, lowering to 890 ° C and holding for 3 hours, about 15
Cool to room temperature at 0 ° C cooling rate. This calcined product is pulverized with a hammer mill and sieved through a sieve of 75 μm mesh to obtain approximately 1 μm.
A 00% sieve pass (D) is obtained (Li: Co molar ratio 1.05: 1). This screened product (D) 193.
30 g, 4.6596 g of zirconia dihydrate, and 1.3427 g of lithium hydroxide monohydrate are mixed with a laboratory mixer. This is heated from room temperature to 900 ° C. at a rate of 150 ° C./hour. After maintaining at 900 ° C. for 3 hours, the temperature is lowered to 850 ° C. and maintained for 3.0 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. Three times the amount of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, followed by centrifugal dehydration. To the dehydrated product, add three times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes again, centrifuge to dehydrate. To the dehydrated product, add three times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes again, centrifuge to dehydrate. This is 15
After drying at 0 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. 7
The sifted product (E) is obtained by sieving through a 5-μm mesh sieve. The composition determined by the ICP method of the _sieved product (E) was Li _1.008 Zr _0.015 Cu _0.00006.
Zn _0.00002 Co _0.9849 O ₂ . Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Example 4 99.91 g of the product (A) passed through the sieve of Example 1 and aluminum nitrate nonahydrate 1.87
Mix 5 g with a lab mixer. One hour per hour
Heat from room temperature to 900 ° C. at a rate of 50 ° C. 9
After maintaining at 00 ° C. for 3 hours, the temperature is lowered to 850 ° C. and maintained for 3.0 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. Five times the volume of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, and then centrifugally dehydrated. To the dehydrated product, 5 times the amount of deionized water is newly added, well dispersed, and after vigorous stirring for 30 minutes, centrifugally dehydrated. A new 5 times volume of deionized water is added thereto, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. After drying at 150 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. 8
After maintaining at 50 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. The product is passed through a sieve of 75 μm mesh to obtain a screened product (F). IC of this sieved product (F)
The composition determined by the P method is Li _1.03 Al _0.005 Co
A _0.995 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Example 5 197.81 g of the product (A) passed through the sieve of Example 1 and 1.559 of aluminum hydroxide
6 g and gallium nitrate (98.3% purity) 1.3000 g
And in a lab mixer. 15 per hour
Heat from room temperature to 960 ° C. at a rate of 0 ° C. 96
After maintaining at 0 ° C. for 2.5 hours, the temperature is lowered to 890 ° C. and maintained for 2.5 hours, and then cooled to room temperature at a cooling rate of about 150 ° C.
Four times the amount of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, followed by centrifugal dehydration. To the dehydrated product, add 4 times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes, centrifugally dehydrate. To this dehydrated product, add 4 times the amount of deionized water, disperse well, and vigorously stir again for 30 minutes.
After stopping, discard the supernatant. A new 4 times amount of deionized water is added, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. A new 4 times amount of deionized water is added, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. After drying at 150 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. 2.0 at 850 ° C
After holding for a time, cool to room temperature at a cooling rate of about 150 ° C. Product that has passed through a sieve with a mesh of 75 μm (G)
Get. The composition obtained by the ICP method of the product (G) passed through the sieve was Li _1.02 Al _0.010 Ga _0.005 CO
A _0.985 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Example 6 Tricobalt tetroxide 3.699
kg, 1.868 kg of nickel hydroxide and 2.872 kg of lithium carbonate at a high speed of 1 with a 20 L Henschel mixer.
After mixing at low speed for 1.0 minute, 0.300 kg of deionized water is added under low speed stirring, followed by mixing and stirring for 1 minute. The mixture is heated from room temperature to 960 ° C. at a rate of 150 ° C./hour. After holding at 960 ° C. for 8 hours, lowering to 890 ° C. and holding for 3 hours, about 150
Cool to room temperature at a cooling rate of ° C. This calcined product is pulverized with a hammer mill, and sieved through a 75 μm mesh sieve to obtain a 99% or more sieve-passed product (H) (Li: Co / Ni molar ratio is 1.17: 1). This screened product (H) 196.
97 g and 3.75 g of aluminum nitrate nonahydrate are mixed with a laboratory mixer. This is heated from room temperature to 960 ° C. at a rate of 100 ° C./hour. 1. at 960 ° C.
After holding for 5 hours, the temperature is lowered to 890 ° C. and held for 2.5 hours, and then cooled to room temperature at a cooling rate of about 100 ° C. This is 4
Double volume of deionized water is added, and after vigorous stirring for 30 minutes, centrifugal dehydration is performed. To the dehydrated product, add 4 times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes, centrifugally dehydrate. To the dehydrated product, add 4 times the amount of deionized water, disperse well, stir vigorously again for 30 minutes, and after stopping, discard the supernatant. Add 4 times more deionized water,
Disperse well, and after vigorous stirring for 30 minutes again, spin-dry. A new 4 times amount of deionized water is added, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. This is 15
After drying at 0 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. 7
The product is passed through a sieve of 5 μm mesh to obtain a sieve-passed product (I). The composition obtained by the ICP method of the product (I) passed through the sieve was Li _1,02 Al _0.005 Ni _0.299 CO
It is a _0,896 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Comparative Example 1 Tricobalt tetroxide 5.284
kg and 2.577 kg of lithium carbonate are mixed in a 20 L Henschel mixer at a high speed for 1 minute, then at a low speed for 1.0 minute, 0.300 kg of deionized water is added under low speed stirring, and then mixed and stirred for 1 minute. The mixture is heated from room temperature to 900 ° C. at a rate of 100 ° C./hour.
After the temperature is maintained at 900 ° C. for 3 hours, the temperature is lowered to 890 ° C. and maintained for 3 hours, and then cooled to room temperature at a cooling rate of about 100 ° C. This calcined product is pulverized with a hammer mill and sieved through a sieve of 75 μm mesh to obtain an almost 100% sieved product (J) (Li: Co molar ratio: 1.05: 1). 189.55 g of this sieved product (J) and 4.6 of aluminum hydroxide
789 g and 1.8744 g of digallium trioxide are mixed in a laboratory mixer. This is heated from room temperature to 960 ° C. at a rate of 150 ° C./hour. After maintaining at 960 ° C. for 2.5 hours, the temperature is lowered to 890 ° C. and maintained for 2.5 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. Four times the amount of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, followed by centrifugal dehydration. To the dehydrated product, add 4 times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes, centrifugally dehydrate. To the dehydrated product, add 4 times the amount of deionized water, disperse well, stir vigorously again for 30 minutes, and after stopping, discard the supernatant. A new 4 times amount of deionized water is added, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. A new 4 times amount of deionized water is added, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. This one
After drying at 50 ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C.
The product is passed through a sieve of 75 μm mesh to obtain a sieve-passed product (K). The composition determined by the ICP method of the _sieved product (K) is Li _1.03 Al _0.03 Ga _0.005 CO
A _0.965 O _2. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Comparative Example 2 96.247 g of the product passed through the sieve (J) of Comparative Example 1, 1.59763 of titanium oxide and 0.8812 g of lithium hydroxide monohydrate were mixed with a laboratory mixer. This is heated from room temperature to 900 ° C. at a rate of 150 ° C./hour. After maintaining at 900 ° C. for 3 hours, the temperature is lowered to 850 ° C. and maintained for 3.0 hours, and then cooled to room temperature at a cooling rate of about 150 ° C. Five times the volume of deionized water is added thereto, and the mixture is vigorously stirred for 30 minutes, and then centrifugally dehydrated. To the dehydrated product, 5 times the amount of deionized water is newly added, well dispersed, and after vigorous stirring for 30 minutes, centrifugally dehydrated. A new 5 times volume of deionized water is added thereto, and the mixture is well dispersed. After vigorous stirring for 30 minutes, the mixture is centrifugally dehydrated. This is 150
After drying at ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. 75
The product is passed through a sieve with a mesh of μm to obtain a sieve-passed product (L).
The composition determined by the ICP method of this sieved product (L) is L
i _1.03 Ti _0.02 CO _0.98 O ₂ . Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Comparative Example 3 Tricobalt tetroxide 77.07
9 g, 42.799 g of lithium hydroxide monohydrate and 3.119 g of aluminum hydroxide are mixed with a laboratory mixer. The temperature is increased from room temperature to 900 at a rate of 100 ° C./hour.
Heat to ° C. 850 after holding at 900 ° C. for 3 hours
C. and maintained for 3.0 hours, then cooled to room temperature at a cooling rate of about 100.degree. This is crushed in a mortar and sieved through a 75 μm mesh sieve to obtain an almost 100% sieved product (M). The composition determined by the ICP method of the sieved product (M) is Li _1.02 Al _0.04 CO _0.96 O ₂ . Table 1 shows the measurement results of the discharge capacity and the capacity retention.

Reference Example 1 To 294.0750 g of the product passed through the sieve (J) of Comparative Example 1, a three-fold amount of deionized water was added, and the mixture was vigorously stirred for 30 minutes, followed by centrifugal dehydration. To the dehydrated product, add three times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes again, centrifuge to dehydrate. To the dehydrated product, add three times the amount of deionized water, disperse well, and after vigorous stirring for 30 minutes again, centrifuge to dehydrate. This is 150
After drying at ° C., it is heated from room temperature to 850 at a rate of 150 ° C./hour. After maintaining at 850 ° C. for 2.0 hours, it is cooled to room temperature at a cooling rate of about 150 ° C. 75
The product is passed through a sieve with a mesh of μm to obtain a product (N) that has passed through the sieve.
The composition determined by the ICP method of this sieved product (N) is L
i _1.003 CoO ₂ . 4.20V, 4,30
The charge / discharge evaluation at V is performed. Table 1 shows the measurement results of the discharge capacity and the capacity retention.

[0026]

[Table 1]

[Effects of the Invention] By the method for producing a lithium-containing cobalt composite oxide having a specific composition according to the present invention and the lithium-containing cobalt composite oxide using the foreign metal compound of the present invention, a discharge capacity higher than that of the conventional lithium cobalt oxide is obtained. , And 4.3 V charging, and a high capacity retention ratio can be obtained. The object of the present invention is to provide a lithium-containing cobalt composite oxide which improves safety, improves overcharge resistance at 4.2 V or more, and can achieve high capacity and long life.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G048 AA04 AB01 AB05 AB08 AC06 AE05 5H029 AJ03 AJ12 AK03 AL06 AL07 AL12 AM02 AM03 AM04 AM05 AM07 CJ01 CJ02 CJ08 CJ12 EJ03 EJ05 HJ02 HJ14 5H050 AA03 GAA17 GA02 DA GA12 HA02 HA14

Claims (2)

[Claims] 1. A general formula _Li a _M b _Ni c Co
_(1-bc) O ₂ (where M is Ti, Ga, Zr, C
represents at least one member selected from the group consisting of r, Al, Cu, and Zn, and a, b, and c each represent 1.00 ≦ a ≦ 1.03;
Represents the numbers 0.0003 ≦ b ≦ 0.015 and 0 ≦ c ≦ 0.3. A) a lithium-containing cobalt composite oxide; 2. A method of converting at least one lithium compound selected from lithium carbonate, lithium hydroxide and lithium acetate and at least one cobalt compound selected from tricobalt tetroxide, cobalt hydroxide and cobalt carbonate into lithium / cobalt. The molar ratio was mixed in the range of 1.05 to 1.25, and after preliminarily heat-treated in the range of 900 ° C to 1050 ° C, pulverized, and Ti, Ga, Zr, Cr, A
l, a mixture of at least one selected from the group consisting of acetate, nitrate, sulfate, carbonate, hydroxide, and oxide of Cu and Zn, heat-treated at a temperature in the range of 800 ° C. to 1050 ° C., and then distilled water 2. The lithium-containing cobalt according to claim 1, wherein excess lithium is extracted and removed with deionized water or the like so that the molar ratio of lithium / cobalt becomes 1.00 or more and 1.03, followed by heating and drying. A method for producing a composite oxide.