JPH11283621A - Nonaqueous electrolyte secondary battery and manufacture of positive electrode material used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously enhance sufficient cycle lifetime performance and storage performance in a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery in which lithium manganese composite oxide is used as a positive electrode material. SOLUTION: In a nonaqueous electrolyte secondary battery, lithium manganese composite oxide is used as a positive electrode material, and a material capable of doping or dedoping lithium is used as a negative electrode material. As the lithium manganese composite oxide, a different kind of metal compound is deposited at the surface of a particle composed of a compound expressed by Lix Mny Oz (wherein 1<=x<=4/3; 1<=y<=2; and 3<=z<=4), followed by heat treatment at temperatures of 200 deg.C or higher and 450 deg.C or lower, thus using lithium manganese composite oxide having a different kind of metal which is prepared by substituting a part of Mn with a different kind of metal having 1-5 atomic equivalents with respect to Mn 100 atomic equivalents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode material.

[0002]

2. Description of the Related Art In recent years, portable electronic devices such as mobile phones, personal information tools, small personal computers and small video cameras have been rapidly reduced in size and cordless, and accordingly, they have been used as power supplies for these devices. There is a demand for smaller and lighter secondary batteries and higher energy density.

As one answer to this demand, lithium ion nonaqueous electrolyte secondary battery have been put into practical use, in particular, the LiCoO ₂ used in the positive electrode, lithium doping and dedoping available carbon material in the negative electrode (e.g. , Non-graphitizable carbon,
When graphite or the like was used, the capacity retention rate was as high as 70% at 1200 cycles, and the self-discharge rate at room temperature storage was 1%.
0% / month or less, no memory effect, and an energy density of 250 W / L or more can be secured.

However, since LiCoO ₂ used as a cathode material contains rare and expensive cobalt as a resource, the lithium ion non-aqueous electrolyte secondary battery is a general aqueous electrolyte secondary battery. It is a high cost secondary battery compared to.

For this reason, lithium manganese composite oxides, which are produced from manganese oxides and lithium compounds in large quantities as positive electrode materials for primary batteries and the like, are abundant in resources and inexpensive as compared with cobalt. Attempts have been made to use it as a positive electrode material for ionic nonaqueous electrolyte secondary batteries.

[0006]

However, in the case of a nonaqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode material, a sufficient cycle is required as compared with a case where a lithium cobalt composite oxide is used as a positive electrode material. At present, life performance and storage performance cannot be realized.

In particular, it is considered that manganese elutes from the lithium manganese composite oxide into the non-aqueous electrolyte during storage in a high-temperature environment, and as a result, it is considered that the battery capacity is reduced. Therefore, in order to prevent manganese from being eluted into the non-aqueous electrolyte from the lithium manganese composite oxide, it is necessary that the lithium content in the lithium manganese composite oxide be slightly stoichiometrically excessive. Suggestions (US
P4, 366, 215, etc.), but the storage characteristics under high temperature conditions are not yet sufficient.

[0008] The present invention is to solve the above-mentioned problems of the prior art, and is directed to a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery using a lithium manganese composite oxide as a positive electrode material. It is an object of the present invention to achieve sufficient cycle life performance and storage performance at the same time.

[0009]

Means for Solving the Problems The present inventors have made it possible to attach a compound of a different metal other than lithium and manganese to the surface of lithium manganese composite oxide particles and heat the particles in a specific temperature range to partially remove Mn. It has been found that the above objects can be achieved by using a lithium manganese heterometallic composite oxide obtained by substituting a lithium metal with a different metal as a positive electrode material, and completed the present invention.

That is, the present invention relates to a lithium-manganese composite oxide in a non-aqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode material and a material capable of doping and dedoping lithium as a negative electrode material. as things, Li _x Mn _y O _z (where, x is 1 ≦ x ≦ 4/3, y is 1 ≦ y ≦ 2, z is 3 ≦ z ≦ 4.)
After adhering a heterogeneous metal compound to the surface of the particles composed of the compound represented by the following, heat treatment at a temperature of 200 ° C or more and 450 ° C or less, a part of Mn is 1 to 100 atomic equivalents of Mn.
Disclosed is a non-aqueous electrolyte secondary battery characterized by using a lithium manganese heterometallic composite oxide obtained by substituting with 5 atomic equivalents of a heterometal.

Further, the present invention provides a method for producing a lithium manganese dissimilar metal composite oxide as the positive electrode material for non-aqueous electrolyte secondary battery, Li _x Mn _y O _z (wherein, x represents 1 ≦
x ≦ 4/3, y is 1 ≦ y ≦ 2, and z is 3 ≦ z
≦ 4. 200 ° C. or higher and 450 ° C. after attaching a heterogeneous metal compound to the surface of particles comprising the compound represented by the formula
There is provided a production method characterized in that a heat treatment is performed at the following temperature, and a part of Mn is replaced with a different metal having 1 to 5 atomic equivalents relative to 100 atomic equivalents of Mn.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The nonaqueous electrolyte secondary battery of the present invention uses a lithium manganese-based composite oxide as a positive electrode material, and uses a material capable of doping and dedoping lithium as a negative electrode material.

In the present invention, a lithium manganese heterometallic composite oxide produced as described below is used as the lithium manganese composite oxide.

[0015] That is, first, Li _x Mn _y O _z (wherein, x
Is 1 ≦ x ≦ 4/3, y is 1 ≦ y ≦ 2, and z is 3 ≦ z ≦ 4. )) (Preferably,
LiMn ₂ O ₄ , Li ₄ Mn ₅ O ₁₂ or Li _{1 + c} Mn _2-c O ₄
A different metal compound (for example, a different metal oxide, a different metal hydroxide, or a lithium different metal composite oxide) is adhered to the surface of the particles composed of (c is 0 ≦ c ≦ 0.05). In this case, a known method can be used for the attachment. For example, in an aqueous solution or suspension of different metal compounds, and by placing the Li _x Mn _y O _z particles, or precipitating or depositing different metal compound on the surface thereof, is reacted with manganese and different metal-substituted You can do it.

Next, L having a different metal compound attached to the surface
By heat treatment at i _x Mn _y O _z particles 200 ° C. or higher 450 ° C. or less of the temperature and substituted with 1-5 atomic equivalent of dissimilar metal part of Mn with respect Mn100 atomic equivalent. Thereby, a lithium manganese different metal composite oxide is obtained. By using such a lithium manganese-based composite oxide as a positive electrode material, it is possible to simultaneously achieve sufficient cycle life performance and storage performance for a non-aqueous electrolyte secondary battery.

If the heat treatment temperature is lower than 200 ° C., the replacement of Mn with the dissimilar metal does not proceed sufficiently, so that the decrease in battery capacity cannot be sufficiently suppressed. There Li _x Mn _y O _z diffuse into the particle interior decreases the surface density of the dissimilar metals, it is impossible to sufficiently suppress the decrease battery capacity. Further, when the substitution amount of the dissimilar metal is less than 1 atomic equivalent or more than 5 atomic equivalents with respect to 100 atomic equivalents of Mn, the decrease in battery capacity cannot be sufficiently suppressed in any case.

The lithium manganese heterometallic composite oxide used in the present invention can be represented by the following formula, for example, Li _x M
n _ya M _b O _z (where x is 1 ≦ x ≦ 4/3 and y
Is 1 ≦ y ≦ 2, z is 3 ≦ z ≦ 4, and a is 0 ≦
a, b is 0.01 ≦ b ≦ 0.05, and M is a dissimilar metal. ). As a dissimilar metal, C
At least one selected from o, Ni, Cu, Zn and V is preferable.

In the non-aqueous electrolyte secondary battery of the present invention, a material capable of doping and undoping lithium is used as a negative electrode material. As such a material, a material similar to a known negative electrode material of a lithium secondary battery can be used. For example, lithium, a lithium-aluminum alloy,
Graphite, pyrolytic carbon, coke (petroleum coke, pitch coke, lime coke, etc.), carbon black (acetylene black, etc.), glassy carbon, organic polymer material fired material (organic polymer material in an inert gas stream Or fired in a vacuum at an appropriate temperature of 500 ° C. or higher),
Carbon fiber, polyacetylene, polyparaphenylene, Mo
O ₂ , TiS ₂ , LiCo _0.5 N or the like can be used. In addition, these materials can be used alone or as a composite or a mixture.

A separator is provided between the negative electrode and the positive electrode without interfering with ion conduction, and a preferable example thereof is a microporous polypropylene film.

As the electrolyte for the non-aqueous electrolyte secondary battery of the present invention, a solution in which an electrolyte such as a lithium salt is dissolved in an organic solvent can be used. Here, the organic solvent is not particularly limited, for example, propylene carbonate,
Carbonates such as ethylene carbonate, butylene carbonate, dimethyl carbonate, ethyl carbonate, methyl carbonate, diethyl carbonate and dipropyl carbonate; formates such as methyl formate, ethyl formate and propyl formate; acetates; propionic acid Esters, ether compounds such as dimethoxyethane, diethoxyethane, diethoxypropanedioxolan, and dioxane; cyclic esters such as γ-butyrolactone and δ-hexyllactone; organic sulfur compounds such as sulfolane and dimethylsulfolane; acetonitrile and propionitrile Or a mixed solvent such as a nitrile.

The electrolyte can be appropriately selected from known electrolytes and used, for example, LiClO ₄ , LiAs
F ₆ , LiPF ₆ , LiBF ₄ , Li (C ₆ H ₅ ) ₄ , LiC
1, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li and the like.

The other components of the non-aqueous electrolyte secondary battery of the present invention, such as a cylindrical or square battery can, a negative electrode current collector or a positive electrode current collector, a battery cover, a gasket, etc. A configuration similar to that of the liquid secondary battery can be employed.

The non-aqueous electrolyte secondary battery of the present invention, for example, a cylindrical battery, can be manufactured, for example, as described below.

First, a strip-shaped negative electrode, a separator, a strip-shaped positive electrode,
Then, four layers are laminated in the order of the separator and the spirally wound electrode body is manufactured by winding the laminated body many times in a spiral shape. Then, a spiral electrode body is manufactured by applying an adhesive tape to a winding end portion of the spiral electrode body.

Next, the spirally wound electrode body thus manufactured is housed in a cylindrical negative electrode can. At this time, insulating plates are provided on both upper and lower surfaces of the spiral electrode body. Further, a negative electrode lead for electrically connecting the belt-shaped negative electrode and the battery can is led out from the negative electrode current collector and welded to the battery can.

Next, after injecting the electrolytic solution into the battery can,
A positive electrode lead for electrically connecting the belt-shaped positive electrode and the battery lid is led out from the positive electrode current collector and welded to the battery lid. Then, the battery can containing the spirally wound electrode body and the electrolytic solution is caulked through an insulating sealing gasket, thereby hermetically fixing the safety valve device having the current interrupting mechanism and the battery lid.
Thus, a cylindrical non-aqueous electrolyte secondary battery can be manufactured.

As described above, the non-aqueous electrolyte secondary battery of the present invention can be preferably applied to a conventional lithium ion cylindrical non-aqueous electrolyte secondary battery. It can be in the shape of a battery, coin-type battery, paper-type battery, or the like.

[0029]

The present invention will be described below in more detail with reference to examples.

Example 1 (Preparation of Positive Electrode Material) Electrolytic manganese dioxide and lithium carbonate were weighed at Mn: Li = 1: 0.52 (molar ratio), and both were mixed in a mortar. This mixture was placed in an alumina boat and heat-treated in an electric furnace at 400 ° C. for 2 hours and then at 750 ° C. for 8 hours in an air atmosphere. The mixture was cooled to room temperature, mixed again in a mortar, placed in an alumina boat, heat-treated at 780 ° C. for 8 hours in an air atmosphere using an electric furnace, and cooled to room temperature. As a result of an analysis by an X-ray diffraction method, the obtained powder was a lithium manganese composite oxide having a crystal structure corresponding to the peak of spinel-type LiMn ₂ O ₄ .

181 g of this lithium manganese composite oxide
Was added to a solution prepared by dissolving 5.82 g of nickel nitrate hexahydrate in 5 L of water. Next, while stirring this mixture,
A 5% aqueous solution of iOH is gradually added dropwise until pH = 9,
Thereafter, the mixture was stirred for 10 minutes.

Next, the stirring was stopped, and the mixture was allowed to stand for about 1 hour to settle solids, and the supernatant was removed by decantation. Next, for washing, after adding water to the sediment and stirring,
The solid was allowed to settle by standing, and the supernatant was removed by decantation.

After the obtained solid was dried at 100 ° C., it was dried in an oven at 250 ° C. for 4 hours, taken out after cooling to room temperature. As a result of analysis by an X-ray diffraction method, the obtained powder is consistent with spinel-type LiMn ₂ O ₄ and has a diffraction peak similar to that of the material before treatment.
According to the analysis result by the chemical analysis, it was a lithium manganese nickel composite oxide having a Ni / Mn abundance ratio of 1.9 / 100.

(Preparation of Positive Electrode) 90 parts by weight of a positive electrode material, 6 parts by weight of graphite as a conductive material, and 4 parts by weight of polyvinylidene fluoride (PVdF) as a binder were mixed, and a dispersion solvent N-methyl-2-pyrrolidone was used. Was added and mixed, then dried and molded into a disk having a diameter of 15.5 mm.

(Production of Battery) A metal Li having a diameter of 17 mm was attached to a battery lid, a polypropylene separator # 2502 was placed thereon, and then a disk-shaped positive electrode pellet was placed. An electrolyte obtained by dissolving LiPF ₆ at 1 mol / L in an equivalent solution of propylene and dimethyl carbonate was injected. Next, the battery was placed on a battery can, and the can and the lid were caulked to produce a coin-type battery having an outer diameter of 20 mm and a height of 2.5 mm.

Example 2 The same materials as in Example 1 were synthesized and treated in the same manner, and the obtained solid was dried at 100 ° C. and then at 400 ° C. to prepare a lithium manganese nickel composite oxide. did. The selected lithium manganese nickel composite oxide was examined by an X-ray diffraction method and found to be spinel-type LiMn ₂ O ₄
And the result of the chemical analysis is Ni / Mn
Was 1.9 / 100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Example 3 As an aqueous nickel nitrate solution charged with 181 g of lithium manganese composite oxide, nickel nitrate hexahydrate 1
A lithium manganese nickel composite oxide was prepared in the same manner as in Example 1, except that a solution in which 7.46 g was dissolved was used. The X-ray diffraction result of the obtained lithium manganese nickel composite oxide powder was consistent with spinel type LiMn ₂ O ₄ , and the result of chemical analysis was that Ni / Mn was 5/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Example 4 The same materials as in Example 1 were synthesized and treated in the same manner, and the obtained solid was dried at 100 ° C. and then at 200 ° C. to prepare a lithium manganese nickel composite oxide. did. The selected lithium manganese nickel composite oxide was examined by an X-ray diffraction method and found to be spinel-type LiMn ₂ O ₄
And the result of the chemical analysis is Ni / Mn
Was 2/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Example 5 The procedure of Example 1 was repeated except that a solution prepared by dissolving 5.82 g of cobalt acetate hexahydrate in 5 L of water was used instead of the aqueous nickel nitrate solution charged with 181 g of lithium manganese composite oxide. A lithium manganese cobalt composite oxide was prepared by the operation. The X-ray diffraction result of the obtained lithium manganese cobalt-based composite oxide powder was spinel-type LiMn ₂
Matches O _4, chemical analysis results, Co / Mn is 2/10
It was 0. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

EXAMPLE 6 Instead of an aqueous nickel nitrate solution charged with 181 g of lithium manganese composite oxide, zinc nitrate hexahydrate 7.4 was added to 5 L of water.
A lithium manganese zinc composite oxide was prepared in the same manner as in Example 1, except that a solution in which 5 g was dissolved was used. The X-ray diffraction result of the obtained lithium manganese zinc composite oxide powder was consistent with spinel type LiMn ₂ O ₄ , and the result of chemical analysis was that Zn / Mn was 2/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Example 7 The procedure of Example 1 was repeated, except that a solution prepared by dissolving 3.75 g of copper nitrate in 5 L of water was used instead of the aqueous nickel nitrate solution charged with 181 g of lithium manganese composite oxide. Manganese copper composite oxide was prepared. The X-ray diffraction result of the obtained lithium manganese copper composite oxide powder was consistent with spinel type LiMn ₂ O ₄ , and the result of chemical analysis was Cu / Mn of 2/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Comparative Example 1 Li obtained by synthesizing in Example 1
A coin-type battery was produced in the same manner as in Example 1, except that Mn ₂ O ₄ was used as it was without being replaced by a different metal.

Comparative Example 2 The same materials as in Example 1 were synthesized and treated in the same manner, and the obtained solid was dried at 100 ° C. and then at 150 ° C. to prepare a lithium manganese nickel composite oxide. did. As a result of examining the selected lithium manganese nickel composite oxide by an X-ray diffraction method, it had a peak corresponding to spinel type LiMn ₂ O _4, and as a result of chemical analysis, Ni / Mn was 2/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Comparative Example 3 Lithium manganese composite oxide 18
A lithium manganese nickel composite oxide was prepared in the same manner as in Example 1, except that a solution prepared by dissolving 2.6 g of nickel nitrate hexahydrate in 5 L of water was used as the aqueous solution of nickel nitrate to which 1 g was added. The X-ray diffraction result of the obtained lithium manganese nickel composite oxide powder was spinel type Li
Matches Mn ₂ O _4, the chemical analysis results, Ni / Mn is 0.
08/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

Comparative Example 4 The same materials as in Example 1 were synthesized and treated in the same manner, and the obtained solid was dried at 100 ° C. and then at 450 ° C. to prepare a lithium manganese nickel composite oxide. did. As a result of examining the selected lithium manganese nickel composite oxide by an X-ray diffraction method, it had a peak corresponding to spinel type LiMn ₂ O _4, and as a result of chemical analysis, Ni / Mn was 2/100. Then, a coin-type battery was produced using this material in the same manner as in Example 1.

(Evaluation) Examples 1 to 7 and Comparative Examples 1 to 4
The following test was performed using the battery prepared in the above.

(Cycle Life Test) Each battery was tested at room temperature under a condition of 0.5 mA / cm ² at 4.2 V upper limit voltage.
Charging to 0.5 mA / cm ² and discharging to a 3.0 V cut-off voltage three times, then 1 mA / cm 2
² , 8 hours at upper limit voltage 4.2V, discharge end voltage 3.0V
A cycle life performance test was performed to discharge the battery until it discharged. The result is shown in FIG.

(High temperature storage test) For each battery, 0.5 m
A / cm ² , charge at 4.2 V upper limit voltage for 12 hours,
Discharging to 5 mA / cm ² and 3.0 V cut-off voltage was repeated three times, and then charging was performed at a current of 0.5 mA / cm ² and an upper limit voltage of 4.2 V for 8 hours. After storage at this time, the battery was stored in an oven at 60 ° C. for one month. After saving,
After taking out these batteries and cooling them to room temperature, 0.5 mA /
Discharge to a 3.0 V cutoff voltage in cm ² and then 0.5
mA / cm ² , charge at 4.2V upper limit voltage for 12 hours,
Repeated twice to 0.5 mA / cm ² , 3.0V cutoff voltage. During the high-temperature storage test, the battery capacities before and after storage were measured, and the capacity retention after storage was calculated. Table 1 shows the obtained results.

[0049]

[Table 1]

(Cycle life test under high temperature conditions) For each battery, 0.5 mA / cm ² , 12 V at 4.2 V upper limit voltage
Charge for 3 hours and discharge to 0.5 mA / cm ² and 3.0 V cut-off voltage three times, then 8 mA at 1 mA / cm ² and upper limit voltage of 4.2 V for 8 hours in an oven at 45 ° C. A cycle life performance test for discharging to 3.0 V was performed. The result is shown in FIG.

From the results shown in FIGS. 1 and 2 and Table 1, in both the cycle life test and the high-temperature storage performance test, the batteries of the examples are comparative examples using a lithium manganese composite oxide not substituted with a dissimilar metal. It is clear that the capacity deterioration is suppressed as compared with the battery No. 1.

When attention is paid to the temperature conditions of the heat treatment,
Generally, as shown in FIG.
It can be seen that when drying is performed at a temperature exceeding ℃, the suppression of the capacity reduction is not sufficient.

When attention is paid to the substitution ratio of manganese to a different metal, the capacity retention ratio is generally higher in the case of substitution than in the case of no substitution, as shown in FIG.

[0054]

According to the non-aqueous electrolyte secondary battery of the present invention,
The charge / discharge cycle life performance can be improved as compared with a non-aqueous electrolyte secondary battery using a conventional lithium manganese composite oxide as a positive electrode material. In addition, the capacity retention rate during storage, particularly under high-temperature storage conditions, can be greatly improved. In addition, it is possible to prevent the battery performance from deteriorating, which is considered to be caused by elution of Mn or the like.

[Brief description of the drawings]

FIG. 1 is a cycle characteristic diagram at room temperature of batteries of Examples and Comparative Examples.

FIG. 2 is a cycle characteristic diagram of the batteries of Examples and Comparative Examples under a high temperature condition.

FIG. 3 is a relationship diagram between a heat treatment temperature and a battery capacity at the time of preparing a positive electrode material.

FIG. 4 is a relationship diagram between an M / Mn ratio in a positive electrode material and a battery capacity.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Osawa 1-1-1 Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Prefecture Inside Sony Energy Tech Co., Ltd. (72) Inventor Yoshito Inoue, Koriyama-shi, Fukushima Prefecture No. 1 Shimosugishita, Takakura, Wadamachi 1 Sony Energy Tech Co., Ltd.

Claims (8)

[Claims] In a non-aqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode material and a material capable of doping and dedoping lithium as a negative electrode material, a lithium manganese composite oxide is used as a lithium manganese composite oxide. _x Mn _y
O _z (where x is 1 ≦ x ≦ 4/3 and y is 1 ≦ y
≦ 2, and z is 3 ≦ z ≦ 4. ), A foreign metal compound is adhered to the surface of the particles of the compound represented by the formula (1), and then heat-treated at a temperature of 200 ° C. or more and 450 ° C. or less. A non-aqueous electrolyte secondary battery using a lithium manganese heterometallic composite oxide obtained by substitution with a metal. 2. A lithium manganese dissimilar metal composite _{oxide, Li x Mn ya M b O} z ( where, x is 1 ≦ x ≦ 4/3
Where y is 1 ≦ y ≦ 2, z is 3 ≦ z ≦ 4, a is 0 ≦ a, b is 0.01 ≦ b ≦ 0.05, and M is a dissimilar metal. is there. The non-aqueous electrolyte secondary battery according to claim 1, which is a compound represented by the formula: 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the dissimilar metal is at least one selected from Co, Ni, Cu, Zn, and V. Wherein Li _x Mn _y O _z is, LiMn ₂ O _4, Li ₄
Mn ₅ O ₁₂ or Li _{1 + c} Mn _2-c O ₄ (c is 0 ≦ c ≦ 0.0
5 The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3. 5. A method for producing a lithium manganese dissimilar metal composite oxide used as a positive electrode material for non-aqueous electrolyte secondary battery, Li _x Mn _y O _z (where, x is 1 ≦ x ≦ 4 /
3, y is 1 ≦ y ≦ 2, and z is 3 ≦ z ≦ 4. ), A foreign metal compound is adhered to the surface of the particles of the compound represented by the formula (1), and then heat-treated at a temperature of 200 ° C. or more and 450 ° C. or less. A production method characterized by replacing with a metal. 6. The lithium-manganese dissimilar metal composite _{oxide, Li x Mn ya M b O} z ( where, x is 1 ≦ x ≦ 4/3
Where y is 1 ≦ y ≦ 2, z is 3 ≦ z ≦ 4, a is 0 ≦ a, b is 0.01 ≦ b ≦ 0.05, and M is a dissimilar metal. is there. The method according to claim 5, which is a compound represented by the formula: 7. The method according to claim 5, wherein the dissimilar metal is at least one selected from Co, Ni, Cu, Zn and V. 8. Li _x Mn _y O _z is, LiMn ₂ O _4, Li ₄
Mn ₅ O ₁₂ or Li _{1 + c} Mn _2-c O ₄ (c is 0 ≦ c ≦ 0.0
5 The method according to any one of claims 5 to 7, wherein