JP4064780B2 - Method for producing lithium cobalt composite oxide - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithium cobalt composite oxide and a method for producing the same, a non-aqueous electrolyte secondary battery, and a portable electronic device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, lithium secondary batteries have begun to be put into practical use as power sources for small electronic devices such as laptop computers, mobile phones, video cameras, etc., as household electrical devices are rapidly becoming portable and cordless.
[0003]
As for this lithium secondary battery, since the report that non-patent document 1 made the lithium cobalt composite oxide useful as a positive electrode active material of the lithium secondary battery in 1980 by Mizushima et al. Research and development on physical cathode active materials are actively underway, and many proposals have been made so far.
[0004]
Conventionally, as a technique for increasing the energy density of the positive electrode active material, for example, a lithium cobalt composite oxide composition that is lithium rich such as Li _a CoO ₂ (where 1.05 ≦ a ≦ 1.3) On the other hand, a cobalt-rich material such as Li _b CoO ₂ (where 0 <b ≦ 1), and other metals such as Mn, W, Ni, La, Ta, Nb, and Zr are added to the lithium cobalt composite oxide. There have been proposed those doped with ions, those defining the amount of residual Li ₂ CO _{3 in} the lithium cobalt composite oxide, those defining the residual alkali, and the like.
[0005]
Regarding the raw material, for example, a method of firing a mixture of a cobalt oxide and a lithium salt having a substantially spherical shape or an oval shape, an average particle diameter of 1 μm or less, and a plurality of primary particles directly connected to each other (Patent document 1), average particle diameter D (50%) = method using cobalt oxide in the range of 0.5 to 1.5 μm (patent document 2), average particle diameter by atomization method about 0.1, 0 A method in which cobalt oxide powder of 2, 0.5, 1, 5, 10 μm and lithium carbonate are mixed and fired (Patent Document 3), and an apparent density of 0.3 to 1.2 g by the standing method of cobalt oxide / Cm ³ or a positive electrode active material for a non-aqueous electrolyte battery using cobalt oxide having an apparent density in the range of 0.8 to 2.5 g / cm ³ by the tap method (Patent Document 4), an average particle size of 10 μm or less and a specific surface area of 1.0 m ² / g or more A lithium cobalt complex oxide for a lithium ion secondary battery in which the above lithium carbonate and cobalt oxide having a specific surface area of 1.0 to 3.5 m ² / g are reacted, and a production method thereof (Patent Document 5) are proposed. ing.
[0006]
Further, the cobalt content is 68.5 ± 6% by weight, which is substantially expressed by the composition of H _x CoO _y , and the half width of the diffraction peak around 2θ = 36 to 37.5 degrees in X-ray diffraction is 0.8. A mixture of a lithium compound and a cobalt compound having a relation between the cobalt content and the half-value width of greater than 31 degrees and represented by a half-value width (degree) ≧ 7.5-0.1 × cobalt content (%) is calcined. A method for producing a lithium cobalt composite oxide (Patent Document 6) has been proposed.
[0007]
Furthermore, it is obtained after reacting a divalent cobalt compound, an alkali hydroxide, and an alkaline ammonium compound in an aqueous medium to obtain cobalt hydroxide, and then calcining to obtain tricobalt tetroxide. A lithium cobalt composite oxide in which tricobalt tetroxide and a lithium compound are mixed, the average particle diameter of the bottom surface is 1 to 30 μm, the average particle height is 0.2 to 10 μm, and the particle shape is a hexagonal column shape. And the manufacturing method (patent document 7) etc. are proposed.
[0008]
[Non-Patent Document 1]
"Material Research Bulletin" Vol. 15, pp. 783-789 (1980)
[Patent Document 1]
JP-A-5-54888 [Patent Document 2]
Japanese Patent Laid-Open No. 5-94822 [Patent Document 3]
Japanese Patent Laid-Open No. 5-290832 [Patent Document 4]
JP-A-6-76823 [Patent Document 5]
Japanese Patent Laid-Open No. 11-16573 [Patent Document 6]
JP 11-49519 A [Patent Document 7]
Japanese Patent Laid-Open No. 11-292547
[Problems to be solved by the invention]
As described above, the lithium cobalt composite oxide is generally produced by a so-called solid-phase reaction in which a lithium compound such as lithium carbonate and a powder of a cobalt compound such as cobalt oxide are mixed and fired.
[0010]
It has been found that such lithium cobalt composite oxides are significantly affected by the physical properties of the respective lithium compounds and cobalt compounds. In addition, positive electrode active materials having various characteristics are also required for lithium secondary batteries. However, the lithium cobalt composite oxide proposed by the above method is required to be further improved.
[0011]
[Means for Solving the Problems]
More specifically, the present invention provides the following.
[0012]
(1) Lithium-cobalt composite oxidation obtained by heating a mixture of a cobalt compound that releases 0.1 to 5% by weight of NH ₃ when heated at 500 ° C. for 30 minutes. object.
[0013]
(2) The lithium cobalt composite oxide as described above, which is a lithium cobalt oxide for a nonaqueous electrolyte secondary battery.
[0014]
(3) when heated at 500 ° C. 30 min, the lithium-cobalt composite oxide, characterized by heating the mixture of the cobalt compound and the lithium compound which releases NH ₃ 0.1 wt% to 5 wt% or less Production method.
[0015]
(4) The method for producing a lithium cobalt composite oxide as described above, wherein the cobalt compound is cobalt oxyhydroxide.
[0016]
(5) A non-aqueous electrolyte secondary battery, wherein the positive electrode contains the lithium cobalt composite oxide obtained by the method described above as a positive electrode active material.
[0017]
(6) A portable electronic device in which the nonaqueous electrolyte secondary battery described above is incorporated.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the positive electrode active material and the nonaqueous electrolyte secondary battery of the present invention will be further described.
[0019]
Lithium cobalt composite oxide according to the present _{invention, Li x Co 1-y M} y O 2-z (M is a transition metal element not identical with Co, the second group of the periodic table, Group 13, Group 14 and A lithium composite oxide having a composition of one or more elements selected from Group 15 elements, 0.2 ≦ x ≦ 1.2, 0 ≦ y ≦ 0.5, and 0 ≦ z ≦ 1). Preferably, 0.4 ≦ x ≦ 1, 0 ≦ y ≦ 0.1, and 0 ≦ z ≦ 0.1. Such a lithium cobalt composite oxide can be suitably used for a positive electrode active material for a lithium ion non-aqueous electrolyte secondary battery.
[0020]
The lithium cobalt composite oxide according to the present invention includes other elements such as B, Mg, Si, Cu, Ce, Y, Ti, V, Mn, Fe, Sn, Zr, Sb, Nb, Ru, Pb, and Hf. At least one element selected from the group consisting of Ta, La, Pr and Nd may be contained.
[0021]
In the present invention, a cobalt compound that releases NH _{3 in an amount} of 0.1 wt% to 5 wt% when heated at 500 ° C. for 30 minutes is used as a raw material. Ammonia appears to be released before, for example, around 200 ° C. before reaching the temperature at which the cobalt and lithium compounds undergo a sintering reaction. When ammonia is released from a mixture of a cobalt compound and a lithium compound, a minute hole is formed, and then, when further heated, the minute hole is blocked by a sintering reaction, and lithium cobalt. It is considered that some structural change is caused to the composite oxide. Or, when a cobalt compound and a lithium compound undergo a sintering reaction, a small amount of ammonia becomes the core of the solid-phase reaction, which may cause some structural change in the crystal grains or grain boundaries of the lithium cobalt composite oxide. It is.
[0022]
<Cobalt oxyhydroxide>
There is no particular limitation on the production method of the cobalt oxyhydroxide used in the production method of the present invention. For example, compounds obtained by oxidizing a compound having divalent cobalt such as cobalt nitrate, cobalt chloride, and cobalt sulfate with an oxidizing agent and then neutralizing with an alkali can be used.
[0023]
The oxidizing agent is not particularly limited, and examples thereof include air, oxygen, ozone; salts thereof represented by permanganic acid (HMnO ₄ ) and M ³ MnO ₄ ; chromic acid (CrO ₃ ) and M ³ ₂ Cr _2. Related compounds represented by O ₇ , M ³ ₂ CrO ₄ , M ³ CrO ₃ X, CrO ₂ X _2, etc .; Halogens such as F ₂ , Cl ₂ , Br ₂ , I ₂ ; H ₂ O ₂ , Na ₂ Peroxides such as O ₂ and BaO ₂ ; compounds represented by peroxo acids and M ³ ₂ S ₂ O ₈ , M ³ ₂ SO ₅ , H ₂ CO ₃ , CH ₃ CO ₃ H and the like; and ^M 3 ^MClO, tables in ^{_{M 3 BrO, M 3 IO,}} M 3 ClO 3, M 3 BrO 3, M 3 IO 3, M 3 ClO 4, M 3 IO 4, Na 3 H 2 IO 6, KIO 4 , etc. Listed compounds or their salts Can. In the formula, M ³ represents an alkali metal element. The alkali metal element is not particularly limited, and examples thereof include lithium, sodium, potassium, and rubidium. X represents a halogen element.
[0024]
The alkali to be neutralized is not particularly limited, and an aqueous solution of an inorganic hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, ammonium hydroxide or the like is preferable. Can be used. However, ammonium hydroxide is preferred for controlling the amount of ammonia.
[0025]
The cobalt oxyhydroxide is prepared by, for example, dissolving a compound having divalent cobalt such as cobalt nitrate, cobalt chloride, and cobalt sulfate in water to form an aqueous solution, and adding the oxidizing agent and the alkali to neutralize and oxidize. Can be obtained simultaneously. Moreover, after adding the said alkali to the aqueous solution containing the compound which has the said bivalent cobalt and synthesize | combining a bivalent cobalt hydroxide, the said cobalt oxyhydroxide can be obtained by adding an oxidizing agent and oxidizing. it can. Furthermore, after adding the said oxidizing agent to the aqueous solution containing the compound which has the said bivalent cobalt, the said cobalt oxyhydroxide can also be obtained by adding the said alkali and neutralizing. The main component of cobalt oxyhydroxide is CoOOH, but additionally contains Co ₃ O ₄ , CoCO _{3 and the} like. For example, NH _{3 in} cobalt oxyhydroxide is considered that Co and NH ₃ partially exist as a complex.
[0026]
<Lithium compound>
A lithium compound is used in the production method of the present invention. Although a lithium compound is not specifically limited, For example, inorganic lithium salts, such as lithium hydroxide, lithium carbonate, lithium nitrate, can be used suitably. As the lithium compound, lithium carbonate is preferable because it is industrially easily available and inexpensive. The concentration of the lithium compound is preferably high in purity.
[0027]
<Manufacturing method>
In the production method according to the present invention, for example, first, the above cobalt oxyhydroxide and a lithium compound, preferably lithium carbonate, are mixed to obtain a mixture. The mixing may be either a dry method or a wet method, but a dry method is preferred because the production is easy. In the case of dry mixing, it is preferable to use a blender for uniformly mixing the raw materials. The mixing ratio of the raw material lithium compound and cobalt compound in the mixing step is 0.99 to 1.06, preferably 0.99 to 1.02, in terms of the molar ratio of Co atom to Li atom (Li / Co). Is preferred.
[0028]
Next, the mixture is fired. The firing temperature is preferably 700 to 1100 ° C, and more preferably 850 to 1050 ° C. The firing time is 1 to 24 hours, preferably 2 to 10 hours. If the firing temperature is lower than 700 ° C., the lithium cobalt composite oxide cannot be sufficiently synthesized and the raw material cobalt oxyhydroxide and lithium compound remain, which is not preferable. On the other hand, when the firing temperature is higher than 1100 ° C., the target lithium cobalt composite oxide starts to decompose, and the battery characteristics of the lithium secondary battery using the lithium cobalt composite oxide as the positive electrode active material, particularly the capacity due to the voltage at the end of discharge. This is not preferable because deterioration and cycle characteristics deteriorate.
[0029]
Firing may be performed either in the air or in an oxygen atmosphere, and is not particularly limited. After firing, the mixture is appropriately cooled and pulverized as necessary to obtain a lithium cobalt composite oxide. In addition, the pulverization performed as necessary is appropriately performed when the lithium cobalt composite oxide obtained by firing is in a brittlely bonded block shape, and the particles of the lithium cobalt composite oxide itself are It has an average particle diameter and a BET specific surface area. That is, the obtained lithium cobalt composite oxide has an average particle size determined by a laser method of 1 to 30 μm, preferably 3 to 20 μm, particularly preferably 5 to 15 μm, and a BET specific surface area of 0.1 to 2.0 m. ² / g, preferably 0.2 to 1.5 m ² / g, particularly preferably 0.3 to 1.0 m ² / g.
[0030]
The amount of ammonia released with respect to the above cobalt oxyhydroxide is 0.1% to 5.0% by weight, preferably 0.5 to 3.0%. The reason for this is not clear, but it is appropriate when the amount of fine vacancies in the lithium cobalt composite oxide is 0.1 to 5.0%, and when it exceeds 5.0%, the vacancies increase too much. It is expected that the crystal structure suitable for discharge cannot be maintained. Moreover, sufficient effect is not acquired as it is 0.1% or less.
[0031]
<Measurement method of NH ₃ content>
2 g of the sample is weighed, and the gas generated by heating in an inert gas (Ar) at 500 ° C. for 30 minutes is collected. Thereafter, the amount of NH ₃ in the gas collected by an NH ₃ gas detector tube (manufactured by Gastec) was quantified.
[0032]
<Battery preparation method>
The lithium cobalt composite oxide is used for the positive electrode active material of the lithium secondary battery according to the present invention. The positive electrode active material is one raw material of a mixture comprising a positive electrode mixture of a lithium secondary battery, which will be described later, that is, a positive electrode active material, a conductive agent, a binder, and a filler as necessary. Since the lithium secondary battery positive electrode active material according to the present invention is composed of the above lithium cobalt composite oxide, it is easy to knead when preparing a positive electrode mixture by mixing with other raw materials, and the obtained positive electrode The coating property when the mixture is applied to the positive electrode current collector becomes easy.
[0033]
The lithium secondary battery according to the present invention uses the above-described lithium secondary battery positive electrode active material, and includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte containing a lithium salt. The positive electrode is formed, for example, by applying and drying a positive electrode mixture on a positive electrode current collector, and the positive electrode mixture includes a positive electrode active material, a conductive agent, a binder, and a filler added as necessary. Consists of.
[0034]
The positive electrode current collector is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in a configured battery. For example, stainless steel, nickel, aluminum, titanium, calcined carbon, aluminum or stainless steel Examples of the surface include carbon, nickel, titanium, and silver surface-treated.
[0035]
Examples of the conductive agent include graphite, such as natural graphite and artificial graphite, carbon black, acetylene black, carbon fiber, carbon nanotube, metal, nickel powder, and other conductive materials. Examples of natural graphite include scale-like graphite. , Scaly graphite and earthy graphite. These can be used alone or in combination of two or more. The blending ratio of the conductive agent is 1 to 50% by weight, preferably 2 to 30% by weight in the positive electrode mixture.
[0036]
Examples of the binder include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl pyrrolidone, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, Polysaccharides such as fluororubber and polyethylene oxide, thermoplastic resins, polymers having rubber elasticity, and the like can be mentioned, and these can be used alone or in combination of two or more. The blending ratio of the binder is 2 to 30% by weight, preferably 5 to 15% by weight in the positive electrode mixture.
[0037]
The filler suppresses the volume expansion of the positive electrode in the positive electrode mixture, and is added as necessary. As the filler, any fibrous material can be used as long as it does not cause a chemical change in the constructed battery. For example, olefinic polymers such as polypropylene and polyethylene, and fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 weight% is preferable in a positive mix.
[0038]
The negative electrode is formed by applying and drying a negative electrode material on the negative electrode current collector. The negative electrode current collector is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in the constructed battery. For example, stainless steel, nickel, copper, titanium, aluminum, calcined carbon, copper or stainless steel Examples of the steel surface include carbon, nickel, titanium, silver surface-treated, and an aluminum-cadmium alloy.
[0039]
Although it does not restrict | limit especially as a negative electrode material, For example, a carbonaceous material, a metal complex oxide, lithium metal, a lithium alloy etc. are mentioned. Examples of the carbonaceous material include non-graphitizable carbon materials and graphite-based carbon materials. As the metal composite oxide, for _example, Sn ^p M ¹ _-pm in 2 q _{O r} (wherein, ^{M 1} is represents one or more elements selected Mn, Fe, Pb, and Ge, ^{M 2} is Al, B , P, Si, one or more elements selected from Group 1, Group 2, Group 3 and halogen elements of the periodic table, 0 <p ≦ 1, 1 ≦ q ≦ 3, 1 ≦ r ≦ 8 And the like.
[0040]
As the separator, an insulating thin film having a large ion permeability and a predetermined mechanical strength is used. Sheets and non-woven fabrics made of olefin polymers such as polypropylene, glass fibers or polyethylene are used because of their organic solvent resistance and hydrophobicity. The pore diameter of the separator may be in a range generally useful for batteries, and is, for example, 0.01 to 10 μm. The thickness of the separator may be in a range for a general battery, for example, 5 to 300 μm. In the case where a solid electrolyte such as a polymer is used as the electrolyte described later, the solid electrolyte may also serve as a separator. Further, for the purpose of improving the discharge and charge / discharge characteristics, a compound such as pyridine, triethyl phosphite, triethanolamine or the like may be added to the electrolyte.
[0041]
The non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte or an organic solid electrolyte is used. Examples of the non-aqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, and 2-methyl. Tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2- One or more aprotic organic solvents such as oxazodinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propane sultone Mixed solvents thereof.
[0042]
Examples of the organic solid electrolyte include a polyethylene derivative or a polymer containing the same, a polypropylene oxide derivative or a polymer containing the same, and a phosphate ester polymer. The lithium salt, which is soluble in the non-aqueous electrolyte is used, for _{example, LiClO 4, LiBF 4, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl ₄ , salts obtained by mixing one or more of chloroborane lithium, lower aliphatic lithium carboxylate, lithium tetraphenylborate and the like.
[0043]
The shape of the lithium secondary battery according to the present invention can be applied to any of buttons, sheets, cylinders, corners, and the like. The use of the lithium secondary battery according to the present invention is not particularly limited. For example, a notebook computer, a laptop computer, a pocket word processor, a mobile phone, a cordless telephone handset, a portable CD player, an electronic device such as a radio, an automobile, an electric motor Examples include consumer electronic devices such as vehicles and game machines. The lithium secondary battery is included in the nonaqueous electrolyte secondary battery.
[0044]
<Portable electronic devices>
In this invention, the portable electronic device containing said nonaqueous electrolyte secondary battery is provided. Examples of portable electronic devices include notebook computers, pocket word processors, mobile phones, cordless telephone handsets, portable CD players, cameras, video cameras, radios, game machines, and the like.
[0045]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example.
[0046]
Lithium carbonate, NH ₃ content, and 6.0,5.0,1.0,0.1,0.05,0.01 weight% of cobalt oxyhydroxide (QNI Inc. Chem Grade), and Li A uniform mixture was prepared by weighing so that the / Co atomic ratio was 0.99 to 1.060 and thoroughly mixing in a mortar. Next, the mixture is filled in an alumina crucible, put in an electric heating furnace, heated in an air atmosphere, held at a temperature of 700 ° C. to 1100 ° C. for 10 hours and baked, and the resulting fired product is put in the air After cooling with pulverization and classification, lithium cobalt composite oxide (LiCoO ₂ ) was obtained. The average particle diameters were 11.8, 12.5, 12.1, 13.5, 13.5, and 11.9 μm, respectively. Since NH ₃ scatters around 200 ° C., it is not included in LiCoO ₂ after firing.
[0047]
[Example 1]
Using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 5.0% by weight, the mixture was calcined at 900 ° C. for 10 hours to obtain a lithium cobalt composite oxide (LiCoO ₂ ). The average particle size was 12.5 μm.
[0048]
[Example 2]
Lithium cobalt composite oxide (LiCoO ₂ ) obtained by firing at 1020 ° C. for 10 hours using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 1.0% by weight. The average particle size was 12.1 μm.
[0049]
[Example 3]
Lithium cobalt composite oxide (LiCoO ₂ ) obtained by firing at 850 ° C. for 10 hours using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 0.1% by weight. The average particle size was 13.5 μm.
[0050]
[Comparative Example 1]
Lithium cobalt composite oxide (LiCoO ₂ ) obtained by firing at 950 ° C. for 10 hours using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 0.05% by weight. The average particle size was 13.5 μm.
[0051]
[Comparative Example 2]
Lithium cobalt composite oxide (LiCoO ₂ ) obtained by firing at 920 ° C. for 10 hours using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 0.01% by weight. The average particle size was 11.9 μm.
[0052]
[Comparative Example 3]
Lithium cobalt composite oxide (LiCoO ₂ ) obtained by firing at 980 ° C. for 10 hours using lithium carbonate and cobalt oxyhydroxide having an NH ₃ content of 6.0 wt%. The average particle size was 11.8 μm.
[0053]
<Battery performance test>
(I) Production of lithium secondary battery;
91% by weight of the lithium cobalt composite oxides of Examples 1 to 3 and Comparative Examples 1 to 3 manufactured as described above, 6% by weight of graphite powder, and 3% by weight of polyvinylidene fluoride were mixed to obtain a positive electrode agent. A kneaded paste was prepared by dispersing in -methyl-2-pyrrolidinone. The kneaded paste was applied to an aluminum foil, dried, pressed and punched into a disk with a diameter of 15 mm to obtain a positive electrode plate.
[0054]
In FIG. 1, using this positive electrode plate, a lithium secondary battery, that is, a separator 1, a negative electrode 2, a positive electrode 3, a current collector plate 4, a mounting bracket 5, an external terminal 6, an electrolyte solution 7, etc. A non-aqueous electrolyte secondary battery was manufactured. Among these, a metal lithium foil was used for the negative electrode, and 1 mol of LiPF ₆ dissolved in 1 liter of a 1: 1 kneaded solution of ethylene carbonate and diethyl carbonate was used for the electrolyte.
[0055]
(II) battery performance evaluation;
The produced lithium secondary battery was operated at room temperature, and the rapid discharge capacity was measured to evaluate the battery performance.
[0056]
(III) Evaluation method;
In the rapid charge / discharge test, the positive electrode was charged to 4.3 V at a constant current and constant voltage (1.0 C, equivalent to full charge for 1 hour), then 0.2 V at constant current and 2.7 V at 2.0 C. The discharge capacity was measured. The results are shown in FIG. Moreover, the discharge curve was shown in FIG. 2 about the lithium secondary battery which produced the lithium cobalt type complex oxide prepared in Example 1, 2, and 3 and Comparative Examples 1, 2, and 3 as a positive electrode active material.
[0057]
<Experimental result>
The active materials obtained in Examples 1, 2, and 3, and Comparative Examples 1, 2, and 3 were applied to the electrodes, and a charge / discharge test was performed at 2.7 V to 4.3 V (vs. Li / Li +). The charge / discharge curve is shown. At that time, the rapid charge / discharge performance was tested by increasing the current value to 0.2C → 2.0C (0.2C → discharge in 5 hours, 2.0C → discharge in 0.5 hours). It can be seen that the active materials obtained in Examples 1, 2, and 3 have a larger capacity that can be taken out than the active materials obtained in Comparative Examples 1, 2, and 3.
[0058]
Although no reason is uncertain to rapid charge and discharge performance is excellent, NH ₃ contained in the cobalt compound may be scattered in the middle firing, this time to produce fine pores in the crystal structure, the Li during charging and discharging It is considered that it has excellent rapid charge / discharge due to the occurrence of a diffusion path.
[0059]
【The invention's effect】
In the present invention, the lithium secondary composite oxide obtained by using a cobalt compound containing NH _{3 in an amount} of 0.1 wt% or more and 5 wt% or less as a raw material is used as a positive electrode active material. A battery can be provided. By using such a lithium secondary battery, a portable electronic device can be reduced in size and weight.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention.
FIG. 2 is a graph showing the relationship between voltage and discharge capacity for a non-aqueous electrolyte lithium secondary battery according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Separator 2 Negative electrode 3 Positive electrode 4 Current collector plate 5 Mounting bracket 6 External terminal 7 Electrolyte

Claims (2)

A method for producing a lithium-cobalt composite oxide, comprising: heating a mixture of a cobalt compound and a lithium compound that release NH ₃ by 0.1 wt% to 5 wt% when heated at 500 ° C. for 30 minutes . Method for producing the cobalt compound lithium-cobalt composite oxide according to claim 1, wherein the cobalt oxyhydroxide.

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