JP4318002B2 - Method for producing positive electrode active material for non-aqueous electrolyte secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is related to method for producing a positive electrode active substance for a non-aqueous electrolyte secondary battery.
[0002]
[Prior art]
In recent years, as devices become portable and cordless, expectations for non-aqueous electrolyte secondary batteries of small size, light weight, and high energy density are increasing. Known positive electrode active materials for non-aqueous electrolyte secondary batteries include complex oxides of lithium and transition metals such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , and LiMnO ₂ . Development of high-voltage, high-energy density non-aqueous electrolyte secondary batteries in which these positive electrode active materials are combined with a negative electrode active material such as a carbon material capable of occluding and releasing lithium has been underway. In particular, recently, research on complex oxides of lithium and manganese using inexpensive manganese has been promoted.
[0003]
In general, the positive electrode active material used for non-aqueous electrolyte secondary batteries is composed of a complex oxide of lithium and transition metals such as cobalt, nickel, manganese, etc., depending on the type of transition metal used, the capacitance, reversibility, operation The electrode characteristics such as voltage are different.
[0004]
For example, in a nonaqueous electrolyte secondary battery using a composite oxide having a layered rock salt structure such as LiCoO ₂ and LiNi _0.8 Co _0.2 O ₂ as a positive electrode active material, the capacity density is 140 to 160 mAh / g and 190 to 190 respectively. It is relatively high at 210 mAh / g, and in the high voltage range of 2.5 to 4.3 V, it shows a good reversibility with respect to insertion and extraction of lithium. However, cobalt and nickel as raw materials are expensive, and there is a problem that insertion and extraction of lithium do not occur reversibly in a voltage range of 2 V or less.
[0005]
On the other hand, a non-aqueous electrolyte secondary battery using a spinel-type composite oxide composed of LiMn ₂ O _{4 made of} relatively inexpensive manganese as a positive electrode active material has a capacity density of 100 to 120 mAh / g and has the above-mentioned cobalt. Compared to active materials containing nickel and nickel. In addition, the charge / discharge cycle durability is low, and there is a problem of rapid deterioration in a low voltage region of less than 3V. On the other hand, a non-aqueous electrolyte secondary battery using LiMnO ₂ made of manganese as an active material can operate up to a low voltage range of around 2 V, and thus can be expected to have a higher capacity than LiMn ₂ O _4. There is a problem that the cycle durability is lower than that of LiMn ₂ O ₄ .
[0006]
The LiMnO _2, monoclinic LiMnO ₂ of layered rock-salt structure is orthorhombic LiMnO ₂ and alpha-NaMnO ₂ type structure of beta-NaMnO ₂ type structure is known. Since orthorhombic LiMnO ₂ gradually transitions to the spinel phase by repeated charge and discharge, the charge and discharge cycle durability is extremely low.
[0007]
Monoclinic LiMnO ₂ is synthesized by ion exchange of α-NaMnO ₂ synthesized by a normal solid phase reaction method in a non-aqueous solution containing Li ions at a temperature of 300 ° C. or less (ARArmstrong and PGBruce, NATURE , Vol. 381, P499, 1996). It has also been reported that manganese oxide is synthesized by hydrothermal treatment in an aqueous lithium salt solution containing an alkali metal hydroxide other than lithium (Japanese Patent Laid-Open No. 11-21128). However, when monoclinic LiMnO ₂ synthesized by these methods is used as the positive electrode active material, the charge / discharge cycle durability is improved, but LiCoO ₂ , LiNi _0.8 Co _0.2 O ₂ or the like is used as the positive electrode active material. Compared with the water electrolyte secondary battery, the charge / discharge cycle durability was inferior, and it was difficult to adopt it in a practical battery.
[0008]
On the other hand, Fe in LiMnO _2, Ni, Co, composite oxide doped with Cr or Al is has been disclosed in JP-A-10-134812, both the composite oxide of the X-ray diffraction chart of JCPDS 35- Since it is similar to 749, it is recognized as an orthorhombic LiMnO ₂ structure, and the charge / discharge cycle durability is insufficient.
[0009]
[Problems to be solved by the invention]
The present invention can be used in a wide voltage range, the electric capacity is increased, to provide a manufacturing method of the charge-discharge cycle and durable, and inexpensive non-aqueous electrolyte cathode active substance for a secondary battery It shall be the purpose.
[0010]
[Means for Solving the Problems]
The present invention has a monoclinic layered rock-salt structure, represented by _{Li x Mn y M 1-y} O 2 ( however, M is selected Al, Fe, Co, from the group consisting of Ni and Cr 1 or more elements, and 0 <x ≦ 1.1 and 0.5 ≦ y <1) A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a water-soluble lithium compound and Provided is a production method characterized by hydrothermally treating a manganese compound and a compound containing the element M at 130 to 300 ° C. in a strongly basic aqueous solution in which potassium hydroxide or sodium hydroxide is dissolved .
[0011]
_{Li x Mn y M 1-y} O 2 can take two kinds of structure of the orthorhombic and monoclinic as a crystal structure, but in the present invention has a layered rock-salt structure of monoclinic. When a monoclinic crystal is used as a positive electrode active material of a non-aqueous electrolyte secondary battery, charge / discharge cycle durability is excellent. _{However, Li x Mn y M 1-} y O 2 in the present invention is not composed of only monoclinic, it may coexist those slight orthorhombic.
[0012]
In the present invention, it is 0.5 ≦ y <1 in _{Li x Mn y M 1-y} O 2. When y is less than 0.5, the monoclinic layered rock salt structure cannot be maintained. Preferably, 0.65 ≦ y ≦ 0.99 is employed. M is one or more elements selected from the group consisting of Al, Fe, Co, Ni, and Cr. In particular, when M is Al, the nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention is used. It is preferable because the electric capacity becomes high.
[0013]
In the production method of the present invention, in the _{Li x Mn y M 1-y} O 2 potassium hydroxide with a water-soluble lithium compound in order to obtain or strongly basic aqueous solution of sodium hydroxide is dissolved, manganese compound (hereinafter And a compound containing element M (hereinafter referred to as M source material) are hydrothermally treated at 130 to 300 ° C. As the method for adding the Mn source material and the M source material to the strongly basic aqueous solution, the following two methods are preferably employed.
1) Add Mn source material and M source material after mixing them in advance.
2) The M source material is dissolved in a strongly basic aqueous solution in which the water-soluble lithium compound and potassium hydroxide or sodium hydroxide are dissolved , and the Mn source material is added to the aqueous solution.
[0014]
According to the method of 1), it preferred as easy to Mn and M is uniformly distributed in the resulting positive electrode active material. In particular, when a hydroxide, oxide or oxyhydroxide obtained by coprecipitation of the Mn source material and the M source material is contained in the strong basic aqueous solution, Mn and M are more uniformly distributed. Therefore, it is preferable. In the method 2), since the M source material is dissolved in the aqueous solution, it easily reacts with the Mn source material, so that Mn and M are uniformly distributed in the obtained positive electrode active material.
[0015]
When M is Al, the method of 2) is preferable, and it is preferable to dissolve NaAlO ₂ , KAlO ₂ , LiAlO ₂ or the like in a strongly basic aqueous solution because homogeneous LiMn _x Al _1-x O ₂ can be synthesized. .
[0016]
Further, in the manufacturing method of the present invention, the uniformity of the crystal working resistance and composite oxide obtained, but dissolving the water-soluble lithium compound in a strongly basic aqueous solution, in particular water-soluble lithium compound hydroxide Lithium is preferred.
[0017]
The strongly basic aqueous solution in the present invention preferably has a pH of 11 or more. The strongly basic solution, since the impurities are less likely to remain in the resulting positive electrode active material, causing dissolved water potassium oxide or sodium hydroxide. Potassium hydroxide and sodium hydroxide may be used alone or in combination. Further, the strong basic aqueous solution may contain chlorine ions, bromine ions, nitrate ions, acetate ions, oxalate ions and the like in addition to the hydroxide ions as anions.
[0018]
In the production method of the present invention, examples of the Mn source material include oxides (Mn ₂ O ₃ , MnO, MnO _2, etc.), oxide hydrates, oxyhydroxides, and the like. A compound is preferred. These Mn source materials may be used alone or in combination of two or more.
[0019]
In the production method of the present invention, metal M, hydroxide, oxide, oxyhydroxide, chloride, nitrate, etc. are used as the M source material. These M source materials may be used alone or in combination of two or more.
[0020]
As a production method of the present invention, for example, 0.05 to 5 mol of a lithium compound such as lithium hydroxide and lithium chloride and 5 to 100 mol of potassium hydroxide or sodium hydroxide are dissolved per 1 kg of pure water so as to be strongly basic. Prepare an aqueous solution. Next, after adding and mixing the Mn source material and the M source material to this aqueous solution, the obtained mixture is placed in a hydrothermal reactor such as an autoclave and subjected to a hydrothermal reaction. As hydrothermal reaction conditions, it is usually preferable to react at a temperature of 130 to 300 ° C for 0.5 hour to 14 days, and it is particularly preferable to react at a temperature of 200 to 250 ° C for 1 to 48 hours.
[0021]
In the production method of the present invention, it is usually preferable to add about 0.1 to 10 g of the Mn source material to 100 mL of the strongly basic aqueous solution, and particularly preferably 0.5 to 3 g. Moreover, it is preferable to add about 0.02-5g normally, and it is preferable to add 0.1-1g especially M source raw material.
[0022]
After completion of the hydrothermal reaction, in order to remove the remaining unreacted raw materials such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, the reaction product is washed with ethanol, filtered, and dried to obtain a desired monoclinic crystal. _{Li x Mn y M 1-y} O 2 of the layered rock-salt structure.
[0023]
The positive electrode of the nonaqueous electrolyte secondary battery in the present invention is a molded body containing the positive electrode active material, a conductive material, and a binder. As the binder, polyvinylidene fluoride, polytetrafluoroethylene (hereinafter referred to as PTFE), polyamide, carboxymethyl cellulose, acrylic resin, and the like are preferable. As the conductive material, carbon-based conductive materials such as acetylene black, graphite, and ketjen black are preferable. A slurry comprising a mixture of the positive electrode active material, a conductive material and a binder and a solvent capable of dissolving or dispersing the binder, or a kneaded material obtained by kneading the mixture with an organic solvent added thereto is an aluminum foil or a stainless steel foil. It is preferable to form the positive electrode by applying or supporting the positive electrode current collector such as the above.
[0024]
In the non-aqueous electrolyte secondary battery in the present invention, a carbonate is preferable as a solvent for the electrolyte. The carbonate ester can be either cyclic or chain. Examples of cyclic carbonates include propylene carbonate and ethylene carbonate. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like. In this invention, it is preferable to use the said carbonate ester individually or in mixture of 2 or more types, and you may mix and use the said carbonate ester with another solvent.
[0025]
Depending on the material of the negative electrode active material, when a mixture of a chain carbonate ester and a cyclic carbonate ester is used, discharge characteristics, cycle durability, and charge / discharge efficiency may be improved. As solutes, ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ^{− and the} like are used as anions. Preference is given to using lithium salts.
[0026]
Further, a vinylidene fluoride / hexafluoropropylene copolymer (for example, Kyner (trade name) manufactured by Atchem Co.), vinylidene fluoride / perfluoro (propyl vinyl ether) disclosed in JP-A-10-294131 is used as a solvent for the electrolyte solution. A gel polymer electrolyte may be prepared by adding a polymer and adding the above solute, and the polymer electrolyte may be used instead of the electrolytic solution.
[0027]
It is preferable that 0.2-2.0 mol / L of lithium salt is contained in said electrolyte solution or polymer electrolyte. When deviating from this range, the ionic conductivity is lowered and the electrical conductivity is lowered. More preferably, it is 0.5-1.5 mol / L.
[0028]
The negative electrode active material in the present invention is a material that can occlude and release lithium ions. The negative electrode active material is not particularly limited, and examples thereof include lithium metal, lithium alloy, carbon material, periodic table 14 and group 15 oxide, silicon carbide, silicon oxide, titanium sulfide, boron carbide, and the like. As the carbon material, those obtained by pyrolyzing organic substances under various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, scale-like graphite, etc. can be used, and the oxide mainly comprises tin oxide. Compounds can be used. Moreover, copper foil, nickel foil, etc. are used as a negative electrode collector.
[0029]
Anode in the present invention is preferably made of a negative electrode active material and a binder, by adding an organic solvent to thereby prepare a slurry in a mixture of negative electrode active material and a binder, applying the slurry to the metallic foil collector, dried, It is preferable to obtain by pressing.
Moreover, a porous polyethylene, a porous polypropylene film, etc. are used preferably for the separator interposed between a positive electrode and a negative electrode.
Moreover, the shape of the nonaqueous electrolyte secondary battery in the present invention is not particularly limited. A sheet shape (so-called film shape), a folded shape, a wound-type bottomed cylindrical shape, a button shape, or the like is selected depending on the application.
[0030]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.
[0031]
[Example 1]
A bottomed cylindrical container made of PTFE was charged with 100 g of potassium hydroxide, 1.6 g of lithium hydroxide monohydrate and 140 g of pure water, stirred and dissolved, and then 0.21 g of 100 μm thick aluminum foil was added. Dissolved. Subsequently, 1.4 g of manganese oxide (Mn ₂ O ₃ ) powder was added and further stirred. Next, the cylindrical container in which the solution was charged was housed in a stainless steel autoclave, the inside of the autoclave was replaced with nitrogen gas, and then hydrothermally treated at 225 ° C. for 10 hours in a closed system. After completion of the reaction, the autoclave was cooled and the slurry-like contents were taken out and filtered. The filter cake was washed with ethanol to remove lithium hydroxide, potassium hydroxide, etc., and dried to obtain a positive electrode active material powder. .
[0032]
As a result of X-ray diffraction analysis of the powder by CuKα rays, diffraction peaks were observed at 2θ = 18 degrees, 37 degrees, 39 degrees, 45 degrees, 62 degrees, 65 degrees, and 67 degrees, and the powder was in a monoclinic phase. It was found to have a layered rock salt type LiMnO ₂ structure. In addition, a diffraction peak based on the LiMnO ₂ structure of a small amount of orthorhombic phase was observed at 2θ = 15 degrees. In addition, elemental analysis of the powder revealed that it was LiMn _0.75 Al _0.25 O ₂ .
[0033]
The above LiMn _0.75 Al _0.25 O ₂ powder, acetylene black, and PTFE powder were mixed at a weight ratio of 80: 16: 4, kneaded while adding toluene to form a sheet, and then dried to a thickness of 150 μm. A 20 μm thick aluminum foil was used as the positive electrode current collector. For the separator, porous polyethylene having a thickness of 25 μm was used. A metal lithium foil having a thickness of 500 μm was used as a negative electrode, and a nickel foil was used as a negative electrode current collector. As the electrolytic solution, a solution in which 1 mol / L LiPF ₆ was dissolved in a 1: 1 mixed solvent of ethylene carbonate and diethyl carbonate was used.
[0034]
In the argon glove box, the positive electrode and the negative electrode were opposed to each other with a separator interposed between them and housed in a simple stainless steel cell together with the electrolytic solution to obtain a non-aqueous electrolyte secondary battery. After charging to 4.3 V with a constant current of 0.2 mA / cm ^2, the battery was discharged to 2.0 V to determine the initial discharge capacity. Further, the charge / discharge cycle was repeated 50 times at a constant current of 0.2 mA / cm ² . The initial discharge capacity at 2.0 to 4.3 V was 160 mAh / g, and the capacity after 50 charge / discharge cycles was 152 mAh / g.
[0035]
[Example 2]
A positive electrode active material powder was synthesized in the same manner as in Example 1 except that 71 g of sodium hydroxide was used instead of 100 g of potassium hydroxide and 0.36 g of aluminum hydroxide was used instead of 0.21 g of aluminum foil. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. Elemental analysis revealed that it was LiMn _0.85 Al _0.15 O ₂ .
[0036]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 156 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 140 mAh / g.
[0037]
[Example 3]
Using a 1 L PTFE bottomed cylindrical container, an aqueous ammonium hydroxide solution was added to an aqueous solution containing manganese nitrate and aluminum nitrate at a molar ratio of 3: 1 to coprecipitate, heated and dried at 150 ° C. -10 g of aluminum coprecipitated hydroxide (atomic ratio of manganese to aluminum is 3: 1) was obtained.
[0038]
A positive electrode active material powder was obtained in the same manner as in Example 1 except that 1.4 g of the manganese-aluminum coprecipitated hydroxide powder was used instead of the manganese oxide powder and the aluminum foil. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. It was also found by elemental analysis that LiMn _0.75 Al _0.25 O ₂ .
[0039]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 157 mAh / g, and the charge / discharge cycle was 50 times. The latter capacity was 150 mAh / g.
[0040]
[Example 4]
Manganese-cobalt coprecipitated hydroxide (atomic ratio of manganese to cobalt is 3: 1) was obtained in the same manner as in Example 3 except that cobalt nitrate was used instead of aluminum nitrate. Was synthesized. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. Further, it was found by elemental analysis to be LiMn _0.75 Co _0.25 O ₂ .
[0041]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and was evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 152 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 135 mAh / g.
[0042]
[Example 5]
Manganese-nickel coprecipitated hydroxide (atomic ratio of manganese to nickel was 3: 1) was obtained in the same manner as in Example 3 except that nickel nitrate was used instead of aluminum nitrate. Was synthesized. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. It was also found by elemental analysis that LiMn _0.75 Ni _0.25 O ₂ .
[0043]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 158 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 137 mAh / g.
[0044]
[Example 6]
Manganese-iron coprecipitated hydroxide was obtained in the same manner as in Example 3 except that iron nitrate was used instead of aluminum nitrate (the atomic ratio of manganese to iron was 3: 1). Was synthesized. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. It was also found by elemental analysis to be LiMn _0.75 Fe _0.25 O ₂ .
[0045]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 155 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 130 mAh / g.
[0046]
[Example 7]
Manganese-chromium coprecipitated hydroxide was obtained in the same manner as in Example 3 except that chromium nitrate was used instead of aluminum nitrate (the atomic ratio of manganese to chromium was 3: 1). Was synthesized. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. It was also found by elemental analysis that LiMn _0.75 Cr _0.25 O ₂ .
[0047]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 157 mAh / g, and the charge / discharge cycle was 50 times. The latter capacity was 135 mAh / g.
[0048]
[Example 8]
Manganese-cobalt coprecipitated hydroxide (atomic ratio of manganese to cobalt is 17: 3) was obtained in the same manner as in Example 4 except that the molar ratio of manganese nitrate to cobalt nitrate was mixed at 17: 3. The precipitated hydroxide was fired at 550 ° C. to obtain a mixed oxide, and a positive electrode active material powder was synthesized in the same manner as in Example 3 using this mixed oxide. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. Elemental analysis revealed that it was LiMn _0.85 Co _0.15 O ₂ .
[0049]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 159 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 140 mAh / g.
[0050]
[Example 9 (comparative example)]
A positive electrode active material powder was synthesized in the same manner as in Example 3 except that no aluminum nitrate was added. X-ray diffraction analysis was performed in the same manner as in Example 1. As a result, a diffraction peak based on a LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a trace amount of orthorhombic crystals at 2θ = 15 degrees was observed. It was. It was also found by elemental analysis to be LiMnO ₂ .
[0051]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive electrode active material was used, and evaluated in the same manner as in Example 1. As a result, the initial discharge capacity was 150 mAh / g, and 50 charge / discharge cycles were performed. The latter capacity was 90 mAh / g.
[0052]
【The invention's effect】
The nonaqueous electrolyte secondary battery having a positive electrode active material produced in the present invention can be used in a wide voltage range, has a large capacity, and is excellent in charge / discharge cycle durability. Moreover, since the positive electrode active material manufactured by this invention uses cheap manganese instead of conventionally used cobalt and nickel, it is obtained at low cost.

Claims (4)

Has a monoclinic layered rock-salt structure, represented by _{Li x Mn y M 1-y} O 2 ( however, M is, Al, Fe, Co, 1 or more selected from the group consisting of Ni and Cr Element, 0 <x ≦ 1.1, 0.5 ≦ y <1)) A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a water-soluble lithium compound and potassium hydroxide or A production method comprising hydrothermally treating a manganese compound and a compound containing the element M at 130 to 300 ° C in a strongly basic aqueous solution in which sodium hydroxide is dissolved .   The manufacturing method according to claim 1, wherein the compound containing the manganese compound and the element M is coprecipitated to be a hydroxide, an oxide, or an oxyhydroxide and then contained in the strongly basic aqueous solution.   The manufacturing method according to claim 1, wherein the manganese compound is added to the strong basic aqueous solution after the compound containing the element M is dissolved. The manufacturing method according to claim 1 , wherein the water-soluble lithium compound is lithium hydroxide.