KR20030037752A - Synthetic method of metal complex oxide using eutectic method - Google Patents

Abstract

PURPOSE: Provided is a preparation method of complex metal oxides by thermal treating two or more of metal oxides without the conventional processes of grinding, mixing and granulation. The resultant complex metal oxides are used as cathode materials of lithium secondary battery. CONSTITUTION: The complex metal oxides, expressed by the formula: LiNi1-x MxO2(M: Co, Al, Mg, Cr, Cu, Mn, Fe or Ti, 0<=x<=1), and LiMn2-xMxO4(M: Co, Ni, Al, Mg, Cr, Cu, Fe or Ti, 0<=x<=0.5), are prepared by the following steps of: weighing two or more of metal oxides having a melting point lower than 300deg.C and a melting point difference less than 50deg.C, such as lithium acetate(CH3CO2Li·2H2O), nickel acetate((CH3CO2)2Ni·4H2O), manganese acetate((CH3CO2)2Mn·4H2O), cobalt acetate((CH3CO2)2Co·4H2O), hydroxy aluminum, etc.; co-melting two or more metal oxides at 70-300deg.C for 20-40min; calcining at 300-500deg.C for 2-10hrs; and sintering at 700-1000deg.C for 5-75hrs.

Description

Manufacturing method of composite metal oxide using eutectic method {SYNTHETIC METHOD OF METAL COMPLEX OXIDE USING EUTECTIC METHOD}

The present invention relates to a method for producing a composite metal oxide. More specifically, the present invention relates to a method for producing a single-phase composite metal oxide using only a heat treatment process using spontaneous eutectic mixing and a direct thermal reaction, without undergoing the grinding, mixing, and granulation processes required in a typical high temperature solid state method. . Representative composite metal oxides prepared according to the present invention can be used as the positive electrode material of a lithium secondary battery.

As the light weight and shortness of electrical and electronic devices are rapidly accelerated, the demand for light weight, miniaturization, high performance, and high stability of secondary batteries, which are key components in this field, are rapidly increasing. A power source that meets these needs is a lithium secondary battery. Essential components of a lithium secondary battery are a negative electrode, an electrolyte and a positive electrode. Lithium secondary batteries are lithium metal batteries using lithium metal negative electrode and organic solvent electrolyte, lithium ion batteries using carbon negative electrode and organic solvent electrolyte, lithium metal negative electrode and solid polymer electrolyte Lithium polymer battery, and lithium ion polymer battery using a carbon negative electrode and a solid polymer electrolyte.

A positive electrode material may be commonly used regardless of the type of lithium secondary battery. Representative positive electrode materials include lithium / cobalt oxide such as LiCoO ₂ having a layered structure and lithium / nickel oxide such as LiNiO ₂ , and LiMn having a spinel structure. Lithium / manganese oxides such as ₂ O ₄ . In addition, in order to obtain a lithium secondary battery having a high energy density and a long lifespan, a solid solution compound substituted with a second transition metal, that is, the general formula LiNi _1-x M _x O _2, is represented by M is Co, Al, Mg, Lithium / nickel / metal oxides of Cr, Cu, Mn, Fe, or Ti, and lithium / nickel of general formula LiMn _2-x M _x O ₄ , wherein M is Co, Ni, Al, Mg, Cr, Cu, Fe, or Ti / Manganese / metal oxides are also used.

Conventional methods for producing a composite metal oxide, such as a cathode material of a lithium secondary battery, are largely classified into three types. First is a high temperature solid state method of calcination and sintering at solid temperature by grinding, mixing and assembling the solid phase reactant, and secondly, dissolving the solid phase reactant in a solvent to obtain a solution and evaporating the solvent to obtain a gel. The sol-gel method for heat treating the gel, and the third is the hydrothermal method for wet heat treatment of the reactants in a high temperature and high pressure reactor.

The most common manufacturing method is a high temperature solid state method (K. Mizushima, PC Jones, PJ Wiseman, JB Goodenough, Mat. Res. Bull ., 15, 783 (1980)). However, the high temperature solid-state method is not only complicated, but also time-consuming, because the overall process is complicated, and furthermore, as the number of constituents of the composition and the yield increase, the importance of the grinding and mixing process increases to obtain a single phase. Longer

The method for compensating the above disadvantages of the high-temperature solid-state method is the sol-gel method, which uses a spontaneous mixing phenomenon of the fluid (DM Schleich, Solid State Ionics, 70-71, 407 (1994)). According to this method, spontaneous mixing is performed in a solution state in which the reactants are dissolved, and thus no grinding, mixing and assembly processes as in the high temperature solid state method are required. However, since solvents or solvents are used as raw materials in addition to the essential chemical components to dissolve the reactants, a heat treatment process more than necessary to remove them is added later, which causes a lot of energy loss and consumes materials other than the essential chemical components. Uneconomical

In the case of hydrothermal methods (D. Larcher, MR Palacin, GG Amatucci, JM Tarascon, J. Electrochem. Soc ., 144, 408, 1997), the types of complex metal oxides that can be produced are very limited, Must be sealed and continuous and mass production is not possible. In addition, wastewater from these processes causes water pollution.

For crystallization of the composite metal oxide, heat treatment processes such as calcination and sintering are essential. The diffusion phenomenon of the components at high temperatures, an additional effect of the heat treatment process, provides a local mixing effect. In the case of a specific high temperature solid state method, such a local mixing effect is used, and therefore, the grinding process seems to be omitted (Japanese Patent Application Laid-Open No. 55-136131, etc.). However, to produce a cathode material with only a local mixing effect, the particle size and particle size distribution of the reactants must be optimized. Therefore, in this case a process for optimizing the particle size and particle size distribution of the reactants should be included, which is a problem that is usually more difficult than the grinding and mixing process.

Accordingly, an object of the present invention is to improve the manufacturing method of the conventional composite metal oxide as described above, to economically produce a composite metal oxide having the same characteristics as those produced by the conventional method without undergoing grinding, mixing and assembling processes. To provide a way.

It is another object of the present invention to provide a method for producing a complex metal oxide that can be used as a positive electrode material of a lithium secondary battery by a simple method.

It is yet another object of the present invention to provide a method for producing a complex metal oxide which can be used as a capacitor material in a simple manner.

1 is a flowchart illustrating a method of manufacturing lithium / manganese oxide LiMn ₂ O ₄ according to the present invention.

2 is a characteristic diagram showing an X-ray diffraction analysis pattern of the composite metal oxide prepared according to the present invention. FIG. 2A shows lithium / manganese oxide LiMn ₂ O ₄ , and FIG. 2B shows solid solution lithium / nickel / cobalt oxide LiNi _1-x Co _x O ₂ (x = 0, 0.2, 0.3, 0.4, 0.5, 1).

3 is a scanning electron microscope (hereinafter referred to as "SEM") photograph of the surface of the composite metal oxide powder prepared according to the present invention. Figure 3a is a lithium / manganese oxide LiMn ₂ O ₄ , Figure 3b is a lithium / cobalt oxide LiCoO ₂ , Figure 3c is a photograph of the lithium / nickel oxide LiNiO ₂ , Figure 3d solid solution lithium / nickel / cobalt oxide LiNi _0.8 Co _0.2 O ₂ is a photo.

4 illustrates charge and discharge capacity characteristics of a lithium secondary battery including a composite metal oxide prepared according to the present invention as a cathode material. 4A shows lithium / manganese oxide LiMn ₂ O ₄ , FIG. 4B shows lithium / cobalt oxide LiCoO ₂ , and FIG. 4C shows solid solution lithium / nickel / cobalt oxide LiNi _0.8 Co _0.2 O ₂ .

The object of the present invention as described above is achieved through spontaneous mixing of the reactants having a melting point of 300 ° C. or less and a difference in melting point of 50 ° C. or less, that is, a eutectic mixing phenomenon and a high temperature thermal reaction.

In the method for producing the composite metal oxide, it is not necessary to use a solvent or a solvent to obtain a fluid. That is, fluids can be obtained when the minimum reactants containing the essential constituents of the composite metal oxides melt themselves in the absence of solvents, and these fluids can be spontaneously mixed evenly. For example, low melting point compounds such as lithium acetate dihydrate (melting point: 60 ° C.), manganese acetate tetrahydrate (melting point: 68 ° C.), and nickel acetate tetrahydrate (melting point: 107 ° C.) may be combined. Even at temperatures slightly above the melting point of the compounds, they are spontaneously mixed with the combined compounds to form a fluid. In the case of cobalt acetate tetrahydrate, the melting point is relatively high at 298 ° C., so that the compound does not dissolve itself. However, the compound is dehydrated at 71 ° C. and part of it is found to be dissolved in the separated water. Therefore, when cobalt acetate tetrahydrate and lithium acetate dihydrate are present together, a fluid can be formed even at a temperature of about 80 ° C.

The present invention provides an economical method for producing a composite metal oxide using the spontaneous eutectic mixing phenomenon and high temperature thermal reaction. Method for producing a composite metal oxide using the eutectic method according to the present invention is as follows.

Depending on the product to be prepared, two or more metal compounds with similar melting points are each weighed in the correct molar ratio. That is, in the case of LiCoO ₂ , the molar ratio of lithium and cobalt is 1.05: 1.0, and in the case of LiNiO ₂ , the molar ratio of lithium and nickel is 1.05: 1.0, and in the case of LiMn ₂ O ₄ , the molar ratio of lithium and manganese is 1.05: 2.0, LiNi _1-x For M _x O ₂ the molar ratio of lithium, nickel and the second metal is 1.05: 1-x: x (0.2 ≤ x ≤ 0.5), for LiMn _2-x M _x O ₄ the molar ratio of lithium, manganese and second metal Is 1.05: 2-x: x (0 ≦ x ≦ 0.5) and the like.

The starting material (starting material) roneun lithium acetate dihydrate _{(CH 3 CO 2 Li · 2H} 2 O), nickel acetate · tetrahydrate _{((CH 3 CO 2) 2} Ni · 4H 2 O) for carrying out the invention, Manganese Acetate Tetrahydrate ((CH ₃ CO ₂ ) ₂ Mn.4H ₂ O), Cobalt Acetate Tetrahydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O), Hydroxy Aluminum Acetate ((CH ₃ CO ₂₎ ) ₂ AlOH or (CH ₃ CO ₂ ) Al (OH) ₂ ), magnesium acetate, tetrahydrate ((CH ₃ CO ₂ ) ₂ Mg.4H ₂ O), chromium acetate hydroxide ((CH ₃ CO ₂ ) ₇ Cr ₃ (OH) ₂ ), copper acetate, monohydrate ((CH ₃ CO ₂ ) ₂ CuH ₂ O), iron acetate ((CH ₃ CO ₂ ) ₂ Fe), iron acetylacetonate ((CH ₃ COCH = COCH ₃ ) ₃ Fe), titanium oxide acetylacetonate ((CH ₃ COCH = COCH ₃ ) ₂ TiO), barium acetate ((CH ₃ CO ₂ ) ₂ Ba) and calcium acetate hydrate ((CH ₃ CO ₂ ) ₂ Ca XH ₂ O) may be used, such as lithium acetate.2 hydrate has a very high atomic weight of lithium. It is preferable to use it in excess of 5 mol% because it is small and high vapor pressure. In addition, the addition of trace amounts of lithium serves as a catalyst for the growth of the particles. In the present invention can be used irrespective of the particle size and particle size distribution of the starting material.

When two or more metal compounds are heat treated at eutectic temperature, the reactants are eutectic and spontaneously and uniformly mixed. The heat treatment temperature for eutectic depends on the kind of reactants to be mixed, the range is 70-300 ℃, the heat treatment time is 20 to 40 minutes is preferred. A homogeneous fluid mixture is obtained, which is then calcined at 300-500 ° C for 2-10 hours and sintered at 700-1000 ° C for 5-75 hours to obtain a composite metal oxide.

Representative composite metal oxides that can be prepared by the present invention are lithium / cobalt oxide LiCoO ₂ , lithium / manganese oxide LiMn ₂ O ₄ , lithium / nickel oxide LiNiO ₂ , general LiNi that can be used as a positive electrode material of a lithium secondary battery Solid solution lithium / nickel / metal oxide, which may be represented by _1- xMxO ₂ , and M is Co, Al, Mg, Cr, Cu, Mn, Fe or Ti, and 0 ≦ x ≦ 1, and the general formula LiMn _2- xMxO ₄ , and M is Co, Ni, Al, Mg, Cr, Cu, Fe, or Ti, and solid solution lithium / manganese / metal oxides having 0 ≦ x ≦ 0.5. 1 shows a process diagram for the preparation of the lithium / manganese oxide LiMn ₂ O ₄ according to the present invention.

Table 1 below shows the eutectic treatment and sintering temperature in the typical lithium / transition metal oxide manufacturing process according to the present invention.

Chemical composition Eutectic Temperature (℃) Sintering Temperature (℃) LiMn ₂ O ₄ 80 750 LiCoO ₂ 80 900 LiNi _0.5 Co _0.5 O ₂ 110 900 LiNi _0.6 Co _0.4 O ₂ 110 900 LiNi _0.7 Co _0.3 O ₂ 110 850 LiNi _0.8 Co _0.2 O ₂ 110 800 LiNiO ₂ 110 800

X-ray diffraction analysis of the lithium / transition metal oxide prepared by the same method as described above shows that the lithium / manganese oxide LiMn ₂ O ₄ has a spinel structure having a space group Fd3m (FIG. 2A), and It was found that lithium / nickel / cobalt oxides represented by the formula LiNi _1- xCoxO ₂ and where x is 0, 0.2, 0.3, 0.4, 0.5 and 1 are layered phase structures with space group R-3m (FIG. 2B). . Table 2 below shows the lattice constants of the samples calculated from the results of X-ray diffraction analysis, which are the values of literatures of the same component samples prepared according to different preparation methods (I. Saadoune, Thesis, University of Bordeaux I (France) (1992).

Lattice constant a (Å) c (Å) LiCoO ₂ 2.818 14.083 LiNi _0.5 Co _0.5 O ₂ 2.847 14.142 LiNi _0.6 Co _0.4 O ₂ 2.855 14.162 LiNi _0.7 Co _0.3 O ₂ 2.860 14.172 LiNi _0.8 Co _0.2 O ₂ 2.866 14.187 LiNiO ₂ 2.884 14.217

3 is a SEM photograph of the surface of lithium / transition metal oxide powder prepared according to the present invention, which shows the powder morphology and approximate particle size of each product.

The lithium / transition metal oxide prepared according to the present invention can be used as a positive electrode material of a lithium secondary battery. Hereinafter, a lithium secondary battery containing lithium / transition metal oxide prepared by the same method as described above as a positive electrode material, and their performance test results will be described.

To 80% by weight of each lithium / transition metal oxide sample prepared according to the present invention, 10% by weight of acetylene black as a conductive material and 10% by weight of polytetrafluoroethylene (hereinafter referred to as "PTFE") as a binder. Was added to prepare a positive electrode. Ethylene carbonate (hereinafter referred to as "EC") and dimethyl carbonate (hereinafter referred to as "DMC") 1: 1 LiPF ₆ is dissolved in a mixed solvent to form a 1M solution. A lithium battery was constructed using the foil as a negative electrode, and performance tests of these batteries were performed in the following manner.

When LiMn ₂ O ₄ was used as the positive electrode material, the charge / discharge experiment of the battery was carried out by using a constant current method in which a constant current of C / 5 flows in the 3.4-4.3V region. When the solid solution lithium / nickel / cobalt oxide represented by the general formula LiNi _1- xCoxO ₂ and x = 0, 0.2, 0.3, 0.4, 0.5 or 1 is used as the cathode material, the charge / discharge test of the battery is performed in the 2.8-4.3V region. It carried out using the constant current method which flows the constant current of C / 5.

The charge and discharge characteristics of a battery including lithium / manganese oxide LiMn ₂ O ₄ prepared according to the present invention are as shown in FIG. 4A. The initial discharge capacity is 110 mAh / g (3.4-4.3 V), which is 110 mAh / g (3.5-4.3 V) (AG Ritchie, which is a documented value for a battery containing samples of the same component prepared by different manufacturing methods). CO Giwa, JC Lee, P. Bowles, A. Gilmour, J. Allan, DA Rice, F. Brady, SCE Tsang, J. Power Sources , 80, 98 (1999)).

Charge and discharge characteristics of the lithium / cobalt oxide LiCoO ₂ prepared according to the present invention is as shown in Figure 4b. The initial discharge capacity is 149 mAh / g (2.8-4.3 V), which is 150 mAh / g (2.5-4.3 V) (T. Ohzuku, literature) A. Ueda, J. Electrochem. Soc ., 141, 2972 (1994)).

The charge / discharge characteristics of the lithium / nickel / cobalt oxide LiNi _0.8 Co _0.2 O ₂ prepared according to the present invention are as shown in FIG. 4C. The initial discharge capacity is 162 mAh / g, which is 170 mAh / g (AG Ritchie, CO Giwa, JC Lee, P. Bowles, A. Gilmour, which is a documented value for a battery containing the same component samples obtained by different manufacturing methods. , J. Allan, DARice, F. Brady and SCE Tsang, J. Power Sources, 80, 98 (1999)).

Another composite metal oxide that can be prepared according to the present invention can be used as a capacitor material, can be represented by the general formula ATiO ₃ , wherein A / titanium oxide wherein A is Ba, Ca, and / or Sr Can be mentioned. These materials are starting materials of titanium oxide acetylacetonate ((CH ₃ COCH = COCH ₃ ) ₂ TiO), barium acetate ((CH ₃ CO ₂ ) ₂ Ba) and / or calcium acetate hydrate ((CH ₃ CO ₂ ) ₂ Ca.xH ₂ O) or the like.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the embodiments are only illustrative of the present invention, and the scope of the present invention is not limited thereto.

Example 1

Preparation of LiMn ₂ O ₄

10.71g of lithium acetate (0.105 mol) of dihydrate (CH ₃ CO ₂ Li _· 2H ₂ O) and 49.02g (0.2 mole), manganese acetate tetrahydrate ((CH ₃ CO _{2) 2} · 4H ₂ O Mn) of Were put together in an alumina boat and heat-treated at 80 ° C. for 20 minutes for eutectic. The melt was then calcined at 450 ° C. in air for 8 hours and sintered at 750 ° C. for 20 hours in an oxygen atmosphere to obtain lithium / manganese oxide LiMn ₂ O ₄ . The product was confirmed by X-ray diffraction analysis, the results are as shown in Table 2 and Figure 2a. LiMn ₂ O ₄ powder prepared in the above manner was confirmed to have a spinel (spinel) structure having a space group Fd3m.

Comparative Example 1

According to the high temperature solid state method, 7.76 g (0.105 mol) of lithium carbonate (Li ₂ CO ₃ ) and 34.77 g (0.4 mol) of manganese dioxide (MnO ₂ ) were ground and mixed for 1 hour using a grinder or mortar. As the amount of sample increased, the time required for grinding and mixing increased exponentially. The reaction mixture was calcined at 450 ° C. for 8 hours in air and sintered at 750 ° C. for 20 hours in an oxygen atmosphere to obtain lithium / manganese oxide LiMn ₂ O ₄ .

Comparative Example 2

According to the sol-gel method, 7.24 g (0.105 mol) of lithium nitrate (LiNO ₃ ) and 57.41 g (0.2 mol) of manganese nitrate hexahydrate (Mn (NO ₃ ) ₂ .6H ₂ O) were added to 250 ml of water. Dissolved and added a small amount of polyethylene glycol (poly (ethylene glycol)) and 10-fold dilute nitric acid. The obtained solution was placed in a silicon oil bath at 120 ° C. to evaporate water, heat treated at 300 ° C. for 12 hours in air, and sintered at 750 ° C. for 20 hours in air to obtain LiMn ₂ O ₄ .

Example 2

Preparation of LiCoO ₂

Lithium acetate dihydrate _{(CH 3 CO 2 Li · 2H} 2 O) and 24.91g (0.1 mole), cobalt acetate tetrahydrate _{(Co (CH 3 CO 2)} 2 · 4H 2 O) of 10.71g (0.105 mol) Were put together in an alumina boat and heat-treated at 80 ° C. for 20 minutes for eutectic. The reaction mixture was then calcined at 450 ° C. for 8 hours in air and sintered at 900 ° C. for 20 hours in an oxygen atmosphere to obtain lithium / cobalt oxide LiCoO ₂ .

Example 3

Preparation of LiNiO ₂

10.71g of lithium acetate (0.105 mol) of dihydrate (CH ₃ CO ₂ Li _· 2H ₂ O) and 24.89g (0.1 mol) of nickel acetate tetrahydrate, ((CH ₃ CO _{2) 2} Ni · 4H ₂ O) of Were put together in an alumina boat and heat-treated at 110 ° C. for 20 minutes to eutectic. The reaction mixture was then calcined at 450 ° C. for 8 hours in air and sintered at 800 ° C. for 20 hours in an oxygen atmosphere to obtain lithium / nickel oxide LiNiO ₂ .

Example 4

Preparation of Solid Solution LiNi _0.8 Co _0.2 O ₂

10.71 g (0.105 mole) of lithium acetate dihydrate, 19.91 g (0.08 mole) of nickel acetate tetrahydrate and 4.98 g (0.02 mole) of cobalt acetate tetrahydrate ((CH ₃ CO ₂ ) ₂ Co.4H ₂ O) was eutectic by heat treatment at 110 ° C. for 20 minutes. The reaction mixture was calcined at 450 ° C. for 8 hours in air and sintered at 800 ° C. for 20 hours in an oxygen atmosphere to obtain a solid solution lithium / nickel / cobalt oxide LiNi _0.8 Co _0.2 O ₂ .

Example 5

Preparation of Solid Solution LiNi _0.7 Co _0.3 O ₂

10.71 g (0.105 mole) of lithium acetate dihydrate, 17.42 g (0.07 mole) of nickel acetate tetrahydrate and 7.47 g (0.03 mole) of cobalt acetate tetrahydrate were heat-treated at 110 ° C. for 20 minutes. The reaction mixture was then calcined at 450 ° C. for 8 hours in air and sintered at 850 ° C. for 20 hours in an oxygen atmosphere to obtain a solid solution lithium / nickel / cobalt oxide LiNi _0.7 Co _0.3 O ₂ .

Example 6

Preparation of Solid Solution LiNi _0.6 Co _0.4 O ₂

10.71 g (0.105 mole) of lithium acetate dihydrate, 14.93 g (0.06 mole) of nickel acetate tetrahydrate and 9.96 g (0.04 mole) of cobalt acetate tetrahydrate were heat-treated at 110 ° C. for 20 minutes. The reaction mixture was then calcined at 450 ° C. for 8 hours in air and sintered at 900 ° C. for 20 hours in an oxygen atmosphere to obtain a solid solution lithium / nickel / cobalt oxide LiNi _0.6 Co _0.4 O ₂ .

Example 7

Preparation of Solid Solution LiNi _0.5 Co _0.5 O ₂

10.71 g (0.105 mole) of lithium acetate.2 hydrate, 12.44 g (0.05 mole) of nickel acetate.4 hydrate, and 12.45 g (0.05 mole) of cobalt acetate.4 hydrate were heat-treated at 110 ° C. for 20 minutes. The reaction mixture was then calcined at 450 ° C. for 8 hours in air and sintered at 900 ° C. for 20 hours in an oxygen atmosphere to obtain a solid solution lithium / nickel / cobalt oxide LiNi _0.5 Co _0.5 O ₂ .

According to the present invention, a method for producing a composite metal oxide more economically than the conventional method using the eutectic method is provided. Since the method for producing a composite metal oxide according to the present invention can omit the grinding, mixing, and assembling steps that are essential in the conventional method, it is possible to save facility equipment costs and production costs corresponding to these processes. The composite metal oxide prepared according to the present invention can be used as a material of a positive electrode material or a capacitor for a lithium secondary battery.

Claims (9)

Two or more metal compounds having a melting point of 300 ° C. or lower and a difference in melting point of 50 ° C. or lower are basis weighted at a suitable molar ratio depending on the product, and eutecticed at a temperature between 70-300 ° C. to obtain a homogeneous fluid mixture. Method for producing a composite metal oxide comprising calcining and sintering. The process of claim 1 wherein the heat treatment temperature for calcination is 300-500 ° C. and the heat treatment temperature for sintering is 700-1000 ° C. 7. The method of claim 1, wherein the at least two metal compounds are lithium acetate dihydrate, nickel acetate tetrahydrate, manganese acetate tetrahydrate, cobalt acetate tetrahydrate, hydroxy aluminum acetate, magnesium acetate tetrahydrate, chromium acetate hydroxide. A method selected from the group consisting of roxide, copper acetate. Monohydrate, iron acetate, iron acetylacetonate, barium acetate, calcium acetate hydrate and titanium oxide acetylacetonate. The method of claim 1 wherein the composite metal oxide is a composite oxide LiNi _1-x M _x O ₂ of lithium / nickel / metal M, wherein 0 ≦ x ≦ 1. The method of claim 4, wherein the metal M is selected from the group consisting of Co, Al, Mg, Cr, Cu, Mn, Fe, and Ti. The method of claim 1 wherein said composite metal oxide is a composite oxide LiMn _2- xMxO ₄ of lithium / manganese / metal M, wherein 0 ≦ x ≦ 0.5. The method of claim 6, wherein the metal M is selected from the group consisting of Co, Ni, Al, Mg, Cr, Cu, Fe, and Ti. The method of claim 1, wherein the composite metal oxide is used as a positive electrode material of a lithium secondary battery. The method of claim 1 wherein the composite metal oxide is A / titanium oxide ATiO ₃ , wherein A is Ba, Ca and / or Sr, and is used as a capacitor material.