JP4156358B2 - Lithium cobaltate composite compound, method for producing the same, and nonaqueous electrolyte secondary battery - Google Patents

Description

【００７２】
【表２】

【００７３】
【発明の効果】
以上説明したように、本発明による正極活物質を使用することにより、電池容量、電池負荷特性の優れた非水電解質ニ次電池を得ることができる。
【００７４】
【発明の効果】
以上説明したように、本発明によるコバルト酸リチウムを正極活物質として使用することにより、電池の膨れも抑制し、かつ負荷特性の優れた非水電解質ニ次電池を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithium cobaltate composite oxide, a method for producing the same, and a nonaqueous electrolyte secondary battery.
[0002]
[Prior art]
In recent years, non-aqueous electrolyte secondary batteries have been put into practical use as power sources for small electronic devices such as laptop computers, mobile phones, and video cameras as home appliances become increasingly portable and cordless.
For this non-aqueous electrolyte secondary battery, research and development on lithium cobalt oxide has been actively promoted, and many proposals have been made so far.
[0003]
In a lithium secondary battery including a positive electrode using a lithium-transition metal composite oxide as an active material, BeO, MgO, CaO, SrO, BaO, ZnO, Al ₂ O ₃ , CEO ₂ , As ₂ are formed on the surface of the positive electrode. There has been proposed a lithium secondary battery characterized in that a film comprising O ₃ or a mixture of two or more thereof is formed. (For example, refer to Patent Document 1).
[0004]
From a negative electrode, a positive electrode, and a non-aqueous electrolyte containing a lithium salt, which can be reversibly charged and discharged multiple times, from Ti, Al, Sn, Bi, Cu, Si, Ga, W, Zr, B, and Mo. A positive electrode characterized by using a metal containing at least one selected metal and / or an intermetallic compound obtained by combining a plurality of these metals and / or an oxide is proposed, and a battery using the same is proposed. ing. (For example, see Patent Document 2)
[0005]
[Patent Document 1]
JP-A-8-236114 [Patent Document 2]
Japanese Patent Laid-Open No. 11-16666
[Problems to be solved by the invention]
However, at present, improvement of the performance of the positive electrode active material is demanded, and even if the above method is used, sufficient battery performance cannot be satisfied. In particular, improvements in safety, battery capacity, load characteristics, and improvement in swelling suppression in aluminum laminate batteries are required.
Accordingly, the object of the present invention is to use lithium cobalt oxide useful as a positive electrode active material for a nonaqueous electrolyte secondary battery, which is particularly excellent in load characteristics and swelling suppression when used as a positive electrode active material for a nonaqueous electrolyte secondary battery. A manufacturing method and a non-aqueous electrolyte secondary battery using a positive electrode active material containing the same.
[0007]
[Means for Solving the Problems]
As a result of intensive studies in the above circumstances, the present inventors have found that the above object can be achieved by mixing lithium cobalt oxide and a metal oxide, and have completed the present invention.
The present invention relates to cobalt obtained from cobalt oxyhydroxide having a repose angle of 50 degrees or less, a tap density of 1.3 to 1.8 g / cm ³ , and an average particle diameter of 8 to 15 μm and a lithium compound. and lithium, magnesium oxide, by mixing one or more kinds of metal oxide selected from titanium oxide or zirconium oxide, and characterized by being obtained by modifying the surface of the lithium cobalt oxide in the metal oxide The present invention provides a lithium cobaltate composite compound.
[0008]
The present invention also provides the lithium cobalt oxide composite compound described above, wherein the tap density is 2.40 g / cm ³ or more.
[0009]
Moreover, this invention provides the manufacturing method of the lithium cobaltate composite compound characterized by including the following processes.
First step: After mixing cobalt oxyhydroxide having a repose angle of 50 degrees or less, a tap density of 1.3 to 1.8 g / cm ³ and an average particle diameter of 8 to 15 μm, and a lithium compound. , Firing the mixture to produce lithium cobalt oxide,
Second step: Lithium cobalt oxide obtained in the first step is mixed with one or more metal oxides selected from magnesium oxide, titanium oxide or zirconium oxide , whereby the surface of the lithium cobalt oxide is mixed with the metal. as the second factory to be modified with oxide [0011]
Moreover, this invention provides the nonaqueous electrolyte secondary battery characterized by the positive electrode containing the said lithium cobaltate complex compound as a positive electrode active material.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
That is, the lithium cobaltate composite compound of the present invention is obtained by mixing lithium cobaltate obtained from cobalt oxyhydroxide and a lithium compound with one or more metal oxides selected from magnesium oxide, titanium oxide or zirconium oxide. It is characterized by.
The lithium cobaltate composite compound used in the present invention is preferably obtained from cobalt oxyhydroxide and a lithium compound.
[0013]
Lithium cobaltate obtained from cobalt oxyhydroxide and a lithium compound is Li _x CoO ₂ of the general formula (1) (wherein x represents a number in the range of 0.2 ≦ x ≦ 1.2) or general formula (2) _{Li x Co 1-y M y} O 2-z ( wherein, M is one or more elements selected from the group consisting of transition metal elements or atomic number 9 or more elements excluding Co X represents a number in the range of 0.2 ≦ x ≦ 1.2, y represents a number in the range of 0 <y ≦ 0.4, and z represents 0 ≦ z ≦ 1. Represents a number in the range of 0).
[0014]
_{Moreover, Li x Co 1-y M} y O The _2-z good metallic element also part be those substituted with other metal elements of Co, for example Na, Mg, Al, Ca, Ti, V , Cr, Mn, Fe, Ni, Zn, Si, Ga, Zr, Nb, W, and Mo.
Also, or may be coated with sulfate in Li _x CoO ₂ or _{Li x Co 1-y M y} O 2-z in part replaced by other metal elements on the surface of lithium cobalt oxide Co.
[0015]
The metal oxide formed by mixing with lithium cobalt oxide is at least one selected from magnesium oxide, titanium oxide, or zirconium oxide, but these may be used alone or as a mixture thereof.
The lithium cobaltate composite compound of the present invention preferably has a tap density of 2.40 g / cm ³ or more.
[0016]
The method for producing a lithium cobaltate composite compound of the present invention includes the following steps.
1st process: After mixing cobalt oxyhydroxide and a lithium compound, the process of baking this mixture and manufacturing lithium cobaltate,
Second step: Cobalt oxyhydroxide according to the second step formed by mixing lithium cobaltate obtained in the first step and one or more metal oxides selected from magnesium oxide, titanium oxide or zirconium oxide, It is preferable that the angle of repose is 50 degrees or less and the tap density is 1.3 to 1.8 g / cm ^3.
Further, the cobalt oxyhydroxide preferably forms secondary particles in which primary particles of 0.1 to 1 μm are aggregated, and the average particle diameter of the secondary particles is preferably 8 to 15 μm.
The cobalt oxyhydroxide used in the first step may be obtained by any method. For example, after oxidizing a compound having divalent cobalt such as cobalt nitrate, cobalt chloride, and cobalt sulfate with an oxidizing agent. Those neutralized with an alkali can be used.
[0018]
The oxidizing agent is not particularly limited. For example, air, oxygen, ozone; permanganic acid (HMnO ₄ ) and its salt represented by MMnO _4, etc .; chromic acid (CrO ₃ ) and M ₂ Cr ₂ O ₇ , Related compounds represented by M ₂ CrO ₄ , MCrO ₃ Cl, CrO ₂ Cl _{2 and the} like; Halogens such as F ₂ , Cl ₂ , Br ₂ and I ₂ ; H ₂ O ₂ , Na ₂ O ₂ , BaO _{2 and the} like Peroxy acids and their salts represented by M ₂ S ₂ O ₈ , M ₂ SO ₅ , H ₂ CO ₃ , CH ₃ CO ₃ H, etc .; oxygen acids and MClO, MBrO, MIO, MClO ₃ , Examples thereof include salts thereof represented by MBrO ₃ , MIO ₃ , MClO ₄ , MIO ₄ , Na ₃ H ₂ IO ₆ , KIO _{4 and the} like. In the formula, M represents an alkali metal element.
The alkali is not particularly limited, and examples thereof include aqueous solutions of lithium hydroxide, potassium hydroxide, sodium hydroxide, ammonium hydroxide, and the like.
[0019]
Specifically, the cobalt oxyhydroxide is neutralized by 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. And oxidation can be performed 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.
[0020]
Although the said 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.
[0021]
In the first step of the present invention, for example, the above lithium oxyhydroxide and a lithium compound, preferably lithium carbonate, are mixed to obtain a mixture. Mixing may be either dry or wet, but dry is preferred because it is easy to produce. In the case of dry mixing, it is preferable to use a blender for uniformly mixing the raw materials. The mixing ratio of the lithium compound and cobalt compound as raw materials in the mixing step is 0.99 to 1.06, preferably 0.99 to 1.02, in terms of the molar ratio of Co atoms to Li atoms (Li / Co). It is preferable.
Next, the mixture is fired. The firing temperature is preferably 700 to 1100 ° C and 850 to 1050 ° C. The firing time is 1 to 24 hours, preferably 2 to 10 hours.
[0022]
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 lithium cobalt oxide. In addition, the grinding | pulverization performed as needed is suitably performed, when the lithium cobaltate obtained by baking is a brittle and the block-shaped thing.
The lithium cobalt oxide obtained by the above method has an average particle diameter of 10 to 15 μm, preferably 10 to 13 μm, and further the amount of remaining lithium carbonate is 0.1% by weight or less by laser method measurement.
[0023]
In the second step of the present invention, lithium cobaltate obtained by the above method and a metal oxide are mixed. However, the metal oxide is not particularly limited as long as it is industrially available. The average particle diameter is 1 μm or less, preferably 0.005 to 1 μm, particularly preferably 0.01 to 0.25 μm, as measured by an electron micrograph.
Such a mixing method may be carried out by any method such as dry or wet, but dry mixing is industrially preferable. In the case of dry mixing, it is preferable to use a blender for uniformly mixing the raw materials.
The amount of the metal oxide added to the lithium cobalt oxide is preferably 0.05 to 1% by weight.
Lithium cobaltate obtained from cobalt oxyhydroxide and a lithium compound has a residual lithium carbonate content of 0.1% by weight or less, so its surface condition is improved by mixing with fine metal oxides. And tap density can be increased.
[0024]
Since the lithium cobaltate composite compound of the present invention has the above characteristics, when used as a positive electrode active material of a non-aqueous electrolyte secondary battery, it has high filling properties and high safety, and further has load characteristics and swelling suppression. It is useful as a positive electrode active material for a non-aqueous electrolyte secondary battery having excellent resistance.
[0025]
The non-aqueous electrolyte secondary battery of the present invention is composed of a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte (for example, a lithium salt-containing electrolyte), and the positive electrode is a positive electrode on a positive electrode plate (positive electrode current collector: for example, an aluminum plate). A positive electrode material mixture containing an active material, a conductive agent and a binder is applied. The nonaqueous electrolyte secondary battery of the present invention uses the positive electrode active material as a positive electrode active material constituting the positive electrode plate. In addition, when preparing the positive electrode mixture, instead of manufacturing the positive electrode active material in advance, the lithium composite oxide particles having a configuration satisfying the conditions of the positive electrode active material of the present invention are mixed and mixed uniformly. Also good.
[0026]
Although it does not restrict | limit especially as a negative electrode material used for the negative electrode of the nonaqueous electrolyte secondary battery of this invention, For example, a carbonaceous material, a metal complex oxide, lithium metal, or a lithium alloy etc. are mentioned. Examples of the carbonaceous material include non-graphitizable carbon materials and graphite-based carbon materials. Examples of the metal composite oxide include SnM ¹ _1-x M ² _y O _z (wherein M ¹ is Mn, Fe, Represents one or more selected from Pb or Ge, and M ² represents two or more elements selected from Al, B, P, Si, Group 1, Group 2, Group 3 or halogen elements of the periodic table. X represents a number in the range of 0 <x ≦ 1, y represents a number in the range of 1 ≦ y ≦ 3, and z represents a number in the range of 1 ≦ z ≦ 8) And the like.
[0027]
In the positive electrode mixture, a conductive agent, a binder, a filler, and the like can be added in addition to the positive electrode active material. As the conductive agent, for example, a conductive material selected from the group consisting of natural graphite (such as scaly graphite, scaly graphite, earthy graphite), artificial graphite, carbon black, acetylene black, carbon fiber, metal powder such as nickel powder, and the like. One type or two or more types of sexual materials can be used. Among the above, it is preferable to use graphite and acetylene black as a conductive agent. In addition, the compounding quantity of the electrically conductive agent to a positive mix is 1 to 50 weight%, Preferably it exists in the range of 2 to 30 weight%.
[0028]
Examples of the binder include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl pyrrolidone, ethylene-propylene-diene turbolimer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluoro rubber, One or more of polysaccharides such as polyethylene oxide, thermoplastic resins, and polymers having rubber elasticity can be used. The blending amount of the binder to the positive electrode mixture is preferably in the range of 2 to 30% by weight.
Furthermore, any filler can be used as long as it is a fibrous material that does not cause a chemical change in the nonaqueous electrolyte secondary battery. Usually, an olefin polymer such as polypropylene or polyethylene, glass fiber, or carbon fiber is used. Such fibers are used. The blending amount of the filler in the positive electrode mixture is not particularly limited, but is preferably in the range of 0 to 30% by weight.
In addition, the compounding quantity to the positive mix of the positive electrode active material of this invention is although it does not specifically limit, Preferably it is 60 to 95 weight%, Especially preferably, it exists in the range of 70 to 94 weight%.
[0029]
Next, non-aqueous electrolytes used in non-aqueous electrolyte secondary batteries are, for example, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyl lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl oxalate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl 2-Oxazodinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, at least one kind of aprotic organic solvent such as 1,3-propane sultone And solvent combined, lithium salts such as LiClO ₄ is dissolved in the _{solvent, LiBF 4, LiPF 6, LiCF} 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, chloroborane lithium, It is composed of one or more lithium salts such as lower aliphatic lithium carboxylate and lithium tetraphenylborate.
In addition to the non-aqueous electrolyte, an organic solid electrolyte can also be used. Examples thereof 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.
[0030]
A desired amount of the above compounds can be mixed to constitute a non-aqueous electrolyte secondary battery. The current collector of the electrode is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in the constructed nonaqueous electrolyte secondary battery.For example, stainless steel, nickel, aluminum, titanium, calcined carbon, The surface of aluminum or stainless steel is surface-treated with carbon, nickel, copper, titanium or silver, and the negative electrode is made of copper or stainless steel in addition to stainless steel, nickel, copper, titanium, aluminum, calcined carbon, etc. A material treated with carbon, nickel, titanium, silver, or the like, an Al—Cd alloy, or the like is used.
[0031]
The shape of the nonaqueous electrolyte secondary battery can be applied to any of coins, buttons, sheets, cylinders, corners, and the like.
The use of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. For example, electronic devices such as notebook computers, laptop computers, pocket word processors, mobile phones, cordless phones, portable CDs, radios, automobiles, electric vehicles, games Examples include consumer electronic devices such as devices.
[0032]
【Example】
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.
[0033]
Production Example 1 (lithium cobaltate: sample A)
Cobalt oxyhydroxide and a lithium compound having an average particle diameter of 10 μm, an angle of repose of 45 degrees, and a tap density of 1.5 g / cm ³ are weighed at a mixing ratio of Li / Co ratio of 1.00. Next, use a mortar to mix until uniform. The mixed raw material is put in an alumina crucible and fired at 800 ° C. to 1100 ° C. for 10 hours in the air. After firing, pulverization and classification were performed. The obtained powder was analyzed for the following items (1) to (4).
(1) Particle size (laser type particle size distribution analyzer Microtrac)
(2) Specific surface area (BET method)
(3) Tap density (4) Load characteristic test (coin battery)
[0034]
Production Example 2 (lithium cobaltate: sample B)
The same procedure as in Production Example 1 was performed except that cobalt oxyhydroxide having an average particle diameter of 12 μ, an angle of repose of 42 degrees, and a tap density of 1.6 g / cm ³ was used. The evaluation items of the obtained powder are the same as in Production Example 1.
[0035]
Production Example 3 (lithium cobaltate: Sample C)
The same procedure as in Production Example 1 was conducted except that cobalt oxyhydroxide having an average particle diameter of 14 μ, an angle of repose of 40 degrees, and a tap density of 1.7 g / cm ³ was used. The evaluation items of the obtained powder are the same as in Production Example 1.
[0036]
Comparative production example 1 (lithium cobaltate: sample D)
The same procedure as in Production Example 1 was performed except that cobalt oxide having an average particle diameter of 2 μ, an angle of repose of 63 degrees, and a tap density of 1.1 g / cm ³ was used. The evaluation items of the obtained powder are the same as in Production Example 1.
[0037]
Comparative production example 2 (lithium cobaltate: sample E)
The same procedure as in Example 1 was performed except that cobalt oxide having an average particle diameter of 3 μ, an angle of repose of 60 degrees, and a tap density of 1.2 g / cm ³ was used. The evaluation items of the obtained powder are the same as in Production Example 1.
[0038]
Example 1
Titanium oxide is mixed with lithium cobalt oxide (sample A) obtained in Production Example 1 using a 0.2 wt% mortar until uniform. The obtained powder was analyzed for the following evaluation items (5) to (6). The results are shown in Table 1.
(5) Tap density (6) Load characteristic test (coin battery)
[0039]
Example 2
Titanium oxide is mixed with lithium cobaltate (sample A) obtained in Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0040]
Example 3
Magnesium oxide is mixed with lithium cobalt oxide (sample A) obtained in Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0041]
Example 4
Zirconium oxide is mixed with lithium cobalt oxide (sample A) obtained in Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0042]
Example 5
Zinc oxide is mixed with lithium cobalt oxide (sample A) obtained in Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0043]
Example 6
Titanium oxide is mixed with lithium cobalt oxide (sample B) obtained in Production Example 2 using a 0.2 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0044]
Example 7
Titanium oxide is mixed with lithium cobalt oxide (sample B) obtained in Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0045]
Example 8
Magnesium oxide is mixed with lithium cobalt oxide (sample B) obtained in Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0046]
Example 9
Zirconium oxide is mixed with lithium cobaltate (sample B) obtained in Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0047]
Example 10
Zinc oxide is mixed with lithium cobaltate (sample B) obtained in Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 4. The results are shown in Table 1.
[0048]
Example 11
Titanium oxide is mixed with lithium cobalt oxide (sample C) obtained in Production Example 3 using a 0.2 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0049]
Example 12
Titanium oxide is mixed with lithium cobalt oxide (sample C) obtained in Production Example 3 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0050]
Example 13
Magnesium oxide is mixed with lithium cobalt oxide (sample C) obtained in Production Example 3 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0051]
Example 14
Zirconium oxide is mixed with lithium cobalt oxide (sample C) obtained in Production Example 3 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0052]
Example 15
Zinc oxide is mixed with lithium cobaltate (sample C) obtained in Production Example 3 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0053]
Comparative Example 1
Titanium oxide is mixed with lithium cobalt oxide (sample D) obtained in Comparative Production Example 1 using a 0.2 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0054]
Comparative Example 2
Titanium oxide is mixed with lithium cobaltate (sample D) obtained in Comparative Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0055]
Comparative Example 3
Magnesium oxide is mixed with lithium cobaltate (sample D) obtained in Comparative Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0056]
Comparative Example 4
Zirconium oxide is mixed with lithium cobaltate (sample D) obtained in Comparative Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0057]
Comparative Example 5
Zinc oxide is mixed with lithium cobaltate (sample D) obtained in Comparative Production Example 1 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0058]
Comparative Example 6
Titanium oxide is mixed with lithium cobalt oxide (sample E) obtained in Comparative Production Example 2 using a 0.2 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0059]
Comparative Example 7
Titanium oxide is mixed with lithium cobalt oxide (sample E) obtained in Comparative Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0060]
Comparative Example 8
Magnesium oxide is mixed with lithium cobaltate (sample E) obtained in Comparative Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0061]
Comparative Example 9
Zirconium oxide is mixed with lithium cobalt oxide (sample E) obtained in Comparative Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0062]
Comparative Example 10
Zinc oxide is mixed with lithium cobalt oxide (sample E) obtained in Comparative Production Example 2 using a 0.4 wt% mortar until uniform. The evaluation items of the obtained powder are the same as those in Example 1. The results are shown in Table 1.
[0063]
Comparative Examples 11-16
Table 2 shows the evaluation items of the powder of each sample of Production Examples 1 to 3 and Comparative Example Production Examples 1 and 2.
[0064]
(Measurement condition)
(Measurement of BET specific surface area)
The BET was measured using a Flowsorb 2300 type (manufactured by Shimadzu Corporation).
[0065]
(Tap density measurement method)
50 g of a sample was placed in a 50 ml graduated cylinder, set in a dual automatic tap device manufactured by Yuasa Ionics Co., Ltd., tapped 500 times, the volume was read, and the apparent density was calculated to obtain the tap density.
[0066]
(Measurement of repose angle)
A powder tester PT-N type device (manufactured by Hosokawa Micron) was used. The sample was passed through a sieve having an opening of 250 μm, dropped onto a repose angle measurement table through a funnel, and the repose angle was measured when the mountain shape was stabilized.
[0067]
(Measurement of average particle size)
The measurement was performed under the following conditions using a Microtrac particle size distribution analyzer 9320-X100 (Leed & Northrup). 300 ml of ultrapure water was put into a sample cell built in the particle size distribution analyzer, and then 2 ml of 10% sodium hexametaphosphate was added. The sample was then added to a concentration suitable for the particle size distribution analyzer. The above operation was performed at a ring flow rate of 40 ml / sec. Subsequently, the ultrasonic wave was dispersed at an output of 40 W for 60 seconds, and then the average particle size was measured.
[0068]
(Pressure density measurement)
A ² ton / cm ² press (manufactured by Toyo Shoko Co., Ltd., model: WPN-10) is performed for 1 minute using a mold having a diameter of 15 mm. Thereafter, the weight and volume of the pellet are measured, and the density of the pellet is calculated.
[0069]
<Battery performance test>
(I) Production of coin-type non-aqueous electrolyte secondary battery;
91% by weight of lithium cobaltate of Examples 1 to 3 and Comparative Examples 1 to 2 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, and this was treated with N-methyl. A kneaded paste was prepared by dispersing in -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.
Using this positive electrode plate, a nonaqueous electrolyte secondary battery was manufactured using each member such as a separator, a negative electrode, a positive electrode, a current collector plate, a mounting bracket, an external terminal, and an electrolytic solution. 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 methyl ethyl carbonate was used for the electrolyte.
[0070]
(II) Evaluation of load characteristics The produced coin-type nonaqueous electrolyte secondary battery was operated at room temperature to evaluate the load characteristics. First, after charging the positive electrode to 4.3 V by constant current voltage (CCCV) charging at 0.5 C over 5 hours, charging and discharging to discharge to 2.7 V at a discharge rate of 0.2 C are performed, and these operations are performed. The discharge capacity was measured every cycle. This cycle was repeated 3 times, and the respective discharge capacity arithmetic average values of the first to third cycles were obtained, and this value was defined as the discharge capacity at 0.2C.
The above operation was performed in the same manner at 2C to determine the discharge capacity. Based on these two, a discharge capacity ratio of 2C / 0.2C was calculated. (The larger the better the load characteristics)
[0071]
[Table 1]

[0072]
[Table 2]

[0073]
【The invention's effect】
As described above, by using the positive electrode active material according to the present invention, a nonaqueous electrolyte secondary battery having excellent battery capacity and battery load characteristics can be obtained.
[0074]
【The invention's effect】
As described above, by using the lithium cobalt oxide according to the present invention as the positive electrode active material, it is possible to obtain a non-aqueous electrolyte secondary battery that suppresses battery swelling and has excellent load characteristics.

Claims (4)

Lithium cobaltate obtained from cobalt oxyhydroxide having a repose angle of 50 degrees or less, a tap density of 1.3 to 1.8 g / cm ³ , and an average particle diameter of 8 to 15 μm and a lithium compound; magnesium oxide, by mixing one or more kinds of metal oxide selected from titanium oxide or zirconium oxide, lithium cobalt oxide, characterized by formed by modifying the surface of the lithium cobalt oxide in the metal oxide Compound compound. The lithium cobalt oxide composite compound according to claim 1, wherein the tap density is 2.40 g / cm ³ or more. The manufacturing method of the lithium cobaltate complex compound characterized by including the following processes.
First step: After mixing cobalt oxyhydroxide having a repose angle of 50 degrees or less, a tap density of 1.3 to 1.8 g / cm ³ and an average particle diameter of 8 to 15 μm, and a lithium compound. , Firing the mixture to produce lithium cobalt oxide,
Second step: Lithium cobalt oxide obtained in the first step is mixed with one or more metal oxides selected from magnesium oxide, titanium oxide or zirconium oxide , whereby the surface of the lithium cobalt oxide is mixed with the metal. Second step to modify with oxide   A non-aqueous electrolyte secondary battery, wherein the positive electrode contains the lithium cobaltate composite compound according to claim 1 or 2 as a positive electrode active material.