JP5854521B2 - Method for producing olivine-type silicate compound - Google Patents

Description

  The present invention relates to a production method for obtaining an olivine-type silicate compound that can be synthesized efficiently and simply and can realize a lithium ion battery having excellent battery properties.

  Lithium ion batteries are a type of non-aqueous electrolyte battery and are used in a wide range of fields such as mobile phones, digital cameras, notebook PCs, hybrid cars, and electric cars. Lithium ion batteries mainly use lithium metal oxide as a positive electrode material and a carbon material such as graphite as a negative electrode material.

As this positive electrode material, lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMnO ₂ ), lithium iron phosphate (LiFePO ₄ ), lithium iron silicate (Li ₂ FeSiO ₄ ) and the like are known. Among these, LiFePO ₄ and Li ₂ FeSiO ₄ have an olivine structure and are useful as positive electrode materials for high-capacity lithium ion batteries. In particular, so-called olivine-type silicate compounds such as Li ₂ FeSiO ₄ are excellent positive electrodes. It is attracting attention as a material.

  Such an olivine-type silicate compound is known to be obtained by subjecting a lithium source, a silicic acid source and a transition metal source to a hydrothermal reaction, and can be treated at a low temperature. Useful. Various researches have been conducted on production methods utilizing such hydrothermal synthesis in order to obtain a finer and higher purity olivine-type silicate compound. For example, Patent Document 1 discloses a method in which a lithium source, a silicic acid source and an antioxidant are used as a basic aqueous dispersion, a transition metal source is added thereto, and then subjected to a hydrothermal reaction. Yes. Patent Document 2 discloses a method in which a transition metal source, a lithium source, and a silicic acid source are placed as a basic aqueous dispersion and then subjected to a hydrothermal reaction.

JP 2012-193087 A JP 2012-193088 A

  However, even with the method described in the above-mentioned patent document, there is still room for improvement in order to sufficiently increase the yield of the olivine-type silicate compound.

  Therefore, an object of the present invention is to provide a method for producing an olivine-type silicate compound that can be synthesized in a high yield while being a simple method and can realize a lithium ion battery having excellent battery properties. There is.

  Therefore, the present inventors, in producing an olivine-type silicate compound, are subjected to hydrothermal synthesis using a solvent containing a specific content of polyol together with water, thereby reducing the synthesis yield while being a simple method. The present inventors have found that it can be effectively enhanced and have completed the present invention.

That is, the present invention includes the following components (A), (B), (C) and (D):
(A) MSO ₄ (wherein, M is, Fe, Ni, Co, Al , Zn, V, showing the Zr or Mn) metallic sulphates or (R) in ₂ M (wherein represented by, R represents represents an organic acid residue, M is, Fe, Ni, Co, Al , Zn, V, Zr or an Mn) represented by an organic acid metal Shokushio, (B) a lithium compound,
(C) Silicate compound, and (D) A solvent containing 20 to 80% by mass of polyol and water is mixed, and then hydrothermally reacted at 100 to 200 ° C. to produce an olivine type silicate compound A method is provided.
Moreover, this invention provides the manufacturing method of the positive electrode active material for lithium ion batteries characterized by carrying | supporting carbon on the olivine type silicate compound obtained by the said manufacturing method, and baking it .

  According to the production method of the present invention, a hydrothermal reaction under a low temperature environment of 100 to 200 ° C. can be effectively used, and the synthesis yield of an olivine-type silicate compound is effectively enhanced while being a simple method. It is possible.

Hereinafter, the present invention will be described in detail.
In the production method of the present invention, first, the following components (A), (B), (C) and (D):
(A) Transition metal sulfate represented by MSO ₄ (wherein M represents Fe, Ni, Co, Al, Zn, V, Zr or Mn) or (R) ₂ M (wherein R is An organic acid residue, wherein M represents Fe, Ni, Co, Al, Zn, V, Zr or Mn), (B) a lithium compound,
(C) Silicic acid compound, and (D) A solvent containing 20 to 80% by mass of polyol and water is mixed.

As the transition metal sulfate MSO ₄ of the component (A), FeSO ₄ , NiSO ₄ , CoSO ₄ , Al ₂ (SO ₄ ) ₃ , ZnSO ₄ , V ₂ (SO ₄ ) ₃ , Zr (SO ₄ ) ₂ or MnSO ₄ , and these may be used alone or in combination of two or more. Of these, FeSO ₄ and MnSO ₄ are more preferable, and FeSO ₄ is more preferable. The amount of transition metal sulfate (MSO ₄ ) added is a reaction mixture containing components (A) to (D) from the viewpoint of increasing the synthesis yield of the olivine-type silicate compound and the physical properties of the resulting battery. The total amount is preferably 0.15 to 1.50 mol / l, more preferably 0.50 to 1.40 mol / l, and even more preferably 0.80 to 1.40 mol / l. .
In this case, the Li content in the reaction mixture is preferably 2 mol or more with respect to M.

The organic acid represented by R of the organic acid transition metal salt (R) ₂ M of the component (A) is preferably an organic acid having 1 to 20 carbon atoms, and more preferably an organic acid having 2 to 12 carbon atoms. More specific organic acids include dicarboxylic acids such as oxalic acid and fumaric acid, hydroxycarboxylic acids such as lactic acid, and fatty acids such as acetic acid. The concentration of the organic acid transition metal salt (R) ₂ M in the total amount of the reaction mixture containing component (A) to component (D) is based on the viewpoint of increasing the synthesis yield of the olivine-type silicate compound and the physical properties of the resulting battery. From the viewpoint of increasing, 0.15 to 1.50 mol / l is preferable, 0.5 to 1.40 mol / l is more preferable, and 0.80 to 1.40 mol / l is more preferable.
In this case, Li in the reaction mixture is preferably used in a molar ratio of 2 times or more with respect to the transition metal, and Li: M is more preferably about 2.5: 1 to 3: 1.

Examples of the lithium compound of component (B) include lithium hydroxide (eg, LiOH.H ₂ O), lithium carbonate (Li ₂ CO ₃ ), lithium sulfate, and lithium acetate, with lithium hydroxide and lithium carbonate being particularly preferred. . The concentration of the lithium compound in the total amount of the reaction mixture containing the component (A) to the component (D) is 0.30 from the viewpoint of increasing the synthesis yield of the olivine-type silicate compound and the physical properties of the resulting battery. 3.00 mol / l is preferable, 1.00-2.80 mol / l is more preferable, and 1.50-2.80 mol / l is more preferable.

The silicic acid compound of component (C) is not particularly limited as long as it is a reactive silica compound, and amorphous silica and Na ₄ SiO ₄ (for example, Na ₄ SiO ₄ .H ₂ O) are preferable. Among these, from the viewpoint of suppressing side reactions, it is preferable to use Na ₄ SiO ₄ and to make the reaction mixture containing components (A) to (D) basic. The concentration of the silicic acid compound in the total amount of the reaction mixture containing the components (A) to (D) is 0.15 from the viewpoint of increasing the synthesis yield of the olivine-type silicate compound and the physical properties of the resulting battery. ˜1.50 mol / l is preferable, 0.50 to 1.40 mol / l is more preferable, and 0.80 to 1.40 mol / l is more preferable.

  The solvent of a component (D) contains 20-80 mass% polyol and water. That is, in the component (D), the remainder of the polyol is water. Thereby, when the component (A) to the component (D) are mixed, the polyol acts as a chelating agent or a surfactant, and the dispersibility of each component is enhanced, and the olivine type silicate compound obtained through a hydrothermal reaction. It is estimated that the synthesis yield of can be effectively increased. The polyol contained in the component (D) is preferably a divalent or trivalent alcohol from the viewpoint of effectively suppressing the generation of impurities and increasing the synthesis yield of the olivine silicate compound.

  Specific examples of the divalent alcohol include ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl -1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl , 3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol. It is done. These may be used alone or in combination of two or more.

  Among these dihydric alcohols, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, and 1,4-butane are used from the viewpoint of increasing the synthesis yield of the olivine-type silicate compound and the physical properties of the obtained battery. At least one selected from the group consisting of diols is preferred, ethylene glycol and polyethylene glycol are more preferred, and ethylene glycol is even more preferred. The average added mole number of ethyleneoxy groups in polyethylene glycol is preferably 10 to 600, more preferably 50 to 500, and still more preferably 100 to 400.

  Specific examples of the trivalent alcohol include glycerin, 1,2,4-butanetriol, 1,2,5-pentanetriol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-adamantanetriol, 1,3,5-cyclohexanetriol, and 1,2,3-cyclohexanetriol. These may be used alone or in combination of two or more.

Among these trivalent alcohols, at least one selected from the group consisting of glycerin, trimethylolethane, trimethylolpropane, and 2-methylpropanetriol is preferable, and glycerin is more preferable.
Among the above-mentioned divalent and trivalent alcohols, at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, 1,4-butanediol, and glycerin is preferable, and ethylene glycol and glycerin are preferable. Is more preferable.

  The content of the polyol is 20 to 80% by mass in the component (D) from the viewpoint of effectively acting such a polyol as a chelating agent or a surfactant, and from the viewpoint of favorably promoting the hydrothermal synthesis reaction. , Preferably it is 20-70 mass%, More preferably, it is 22-60 mass%, More preferably, it is 25-55 mass%.

  Component (D) contains water in addition to the above polyol. By containing water in an appropriate amount, the polyol can be more effectively acted as a chelating agent or a surfactant, and the synthesis yield of the olivine-type silicate compound can be increased. Such water may be any of distilled water, ion exchange water and the like.

  The mixing order of component (A) to component (D) is not particularly limited, and they may all be mixed at the same time, and components (A) to (C) are mixed in advance and added to component (D). May be further mixed. Especially, from the viewpoint of improving the dispersibility or solubility of each component and improving the synthesis yield of the olivine-type silicate compound, components (A) to (C) are mixed in advance and added to component (D). Further mixing is preferable.

In addition to the components (A) to (D), an antioxidant may be further added before hydrothermal synthesis. As the antioxidant, hydrosulfite sodium (Na ₂ S ₂ O ₄ ), aqueous ammonia, sodium sulfite and the like can be used. Since the content of the antioxidant in the total amount of the liquid mixture containing the reaction mixture of the components (A) to (D) and the antioxidant, when added in a large amount, the formation of the olivine-type silicate compound is suppressed. An equimolar amount or less is preferable with respect to the transition metal (M), and a molar ratio with respect to the transition metal (M) is more preferably 0.5 or less.

The obtained reaction mixture is preferably basic from the viewpoint of preventing side reactions and dissolving the silicate compound. Specifically, the pH of the reaction mixture is 12.0 to 13.5. Is preferred. The pH of the reaction mixture may be adjusted by adding a base such as sodium hydroxide, but it is more preferable to use Na ₄ SiO ₄ as the silicate compound.

  In the production method of the present invention, the components (A) to (D) are mixed and then hydrothermally reacted at 100 to 200 ° C. The temperature of the hydrothermal reaction is preferably from 130 to 200 ° C, more preferably from 140 to 180 ° C, from the viewpoint of increasing the synthesis yield of the olivine-type silicate compound. The hydrothermal reaction is preferably performed in a pressure vessel, and the pressure when the reaction is performed at 130 to 200 ° C is preferably 0.3 to 1.5 MPa, and the pressure when the reaction is performed at 140 to 180 ° C is It is preferably 0.4 to 1.0 MPa. The hydrothermal reaction time is preferably 1 to 24 hours, more preferably 3 to 12 hours.

By the hydrothermal reaction, primary particles of the olivine-type silicate compound containing the transition metal M are obtained in high yield. Such an olivine type silicate compound is specifically represented by any of the following formulas (1) to (5).
Li ₂ M'SiO ₄ (1)
(In the formula, M ′ represents one or more selected from Fe, Ni, Co and Mn.)
_{Li a 'Fe x Mn y Al} z SiO 4 ··· (2)
(Where, a ′, x, y and z are 1 <a ′ ≦ 2, 0 ≦ x <1, 0 ≦ y <1, 0 <z <2/3, a ′ + 2x + 2y + 3z = 4, and x + y ≠ Indicates a number satisfying 0.)
_{Li a "Fe x Mn y V} z 'SiO 4 ··· (3)
(Where a ^" , x, y and z 'are 1 <a ^" ≤2, 0≤x <1, 0≤y <1, 0 <z'<1, a ^" + 2x + 2y + (2-5) z '= 4 and a number satisfying x + y ≠ 0.)
_{Li a "Fe x Mn y Zr} z" SiO 4 ··· (4)
(Where a ^" , x, y and z ^" are 1 <a ^" ≤2, 0≤x <1, 0≤y <1, 0 <z ^" <0.5, a ^" + 2x + 2y + 4z ^" = 4, And a number satisfying x + y ≠ 0.)
_{Li 2 Fe x Mn y Zn q} SiO 4 ··· (5)
(In the formula, x, y, and q represent numbers satisfying 0 ≦ x <1, 0 ≦ y <1, 0 <q <1, x + y + q = 1, and x + y ≠ 0.)

  The primary particles of the obtained olivine type silicate compound can be isolated as secondary particles by filtering after washing and then drying. Examples of the drying means include spray drying, box drying, fluidized bed drying, external heat drying, freeze drying, and vacuum drying. Of these, spray drying using a spray dryer is preferred. Moreover, when drying, it is good to use the slurry previously prepared using the primary particle of the olivine type silicate compound. The content (solid content concentration) of primary particles of the olivine-type silicate compound in such a slurry is preferably 20 to 60% by mass, more preferably 30 to 50% by mass, from the viewpoint of enhancing the physical properties of the obtained battery. More preferably, it is 35-45 mass%.

At this time, a small amount of a dispersant or a thickener may be added to the slurry, and as the dispersant, for example, a polycarboxylic acid type, a polyether type, a polyacrylic acid type, or the like can be used.
As the thickener, for example, a base such as sodium hydroxide, lithium hydroxide or ammonia, or an organic acid such as acetic acid or citric acid can be used.

  The dried product thus obtained may be classified with a separator, cyclone, sieve or the like during or after drying, or may be pulverized with a mortar pin mill, roll mill, crusher or the like.

  In addition, you may perform the process which carries a carbon on the primary particle or secondary particle of the olivine type | mold silicate compound obtained previously further using an electroconductive carbon material. By doing so, it is possible to form a carbon thin film on the particle surface, further increase the electron conduction area (electron conduction path) of the olivine-type silicate compound, and ensure more sufficient electron conductivity. Become.

  Examples of the conductive carbon material used for the carbon-supporting treatment include carbon such as cellulose, lignin, chitosan, chitin, carbon nanotube, graphene, graphene oxide, carbon black, acetylene black, ketjen black, graphite, graphite, and synthetic fiber. Containing compounds. The amount of the conductive carbon material added in this case is 0.5 to 20% by mass in terms of carbon atoms contained in the conductive carbon material in the primary particle theoretical generation amount of the olivine-type silicate compound obtained after the hydrothermal reaction. Is preferably added in an amount of 2.5 to 17.5% by mass. In adding the conductive carbon material, it is preferable to use a solvent to form a solution from the viewpoint of improving dispersibility. The concentration of the conductive carbon material in the solution is preferably 40% by mass or less, and more preferably 20% by mass or less. Examples of the solvent include distilled water and ion exchange water.

  The amount of the conductive carbon material added is from 0.5 to 20 parts by mass in terms of carbon atoms with respect to 100 parts by mass of the primary particles of the olivine silicate compound in the slurry, from the viewpoint of good charge / discharge capacity and economy. Is preferable, and an amount of 2.5 to 17.5 parts by mass is more preferable.

  Thus, after adding a conductive carbon material using a solvent as needed, it can be set as the positive electrode active material for lithium ion batteries by baking. Firing conditions in the carbon-supporting treatment are 400 ° C. or higher, preferably 400 to 800 ° C. for 10 minutes to 3 hours, preferably 0.5 to 1.5 hours under an inert gas atmosphere or reducing conditions. . By this treatment, a positive electrode active material in which carbon is supported on the surfaces of primary particles or secondary particles of the olivine type silicate compound can be obtained.

  The method for producing a lithium ion battery using the positive electrode active material for a lithium ion battery of the present invention thus obtained is not particularly limited, and any known method can be used. For example, such a positive electrode active material is mixed with additives such as a binder and a solvent to obtain a coating liquid. At this time, if necessary, a conductive additive may be further added and mixed. The binder is not particularly limited, and any known agent can be used. Specific examples include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, and ethylene propylene diene polymer. Moreover, it does not specifically limit as this conductive support agent, Any well-known agent can be used. Specific examples include acetylene black, ketjen black, natural graphite, artificial graphite, and fibrous carbon. Next, such a coating solution is applied onto a positive electrode current collector such as an aluminum foil and dried to obtain a positive electrode.

  The positive electrode active material for a lithium ion battery of the present invention is useful in that it exhibits a very excellent discharge capacity as a positive electrode of a lithium ion battery. A lithium ion battery to which such a positive electrode can be applied is not particularly limited as long as it has a positive electrode, a negative electrode, an electrolytic solution, and a separator as essential components.

  Here, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material structure is not particularly limited, and a known material structure can be used. For example, a carbon material such as lithium metal, graphite, or amorphous carbon. It is preferable to use an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium, particularly a carbon material.

  The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used for an electrolyte solution of a lithium ion battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, oxolanes, and the like. A compound or the like can be used.

The type of the supporting salt is not particularly limited, but an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO ₃ CF ₃ ) ₂ and LiN (SO ₃ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), and organic salt derivatives It is preferable that it is at least 1 sort of.

  The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Example 1]
_{LiOH · H 2 O 4.20g (100mol} ), the _{Na 4 SiO 4 · nH 2 O} 13.98 (50mmol), in a solvent (solvent containing ultrapure water 27.5cm ³ and glycerin 10.0 cm ³ Glycerin content: 27% by mass) was added and mixed (pH at this time was about 13). To this mixed solution, 3.92 g (14.1 mmol) of FeSO ₄ .7H ₂ O, 7.93 g (32.9 mmol) of MnSO ₄ .5H ₂ O and 0.53 g (1.5 mmol) of ZrSO ₄ .4H ₂ O were added. , Mixed. The obtained mixed solution was put into an autoclave and subjected to a hydrothermal reaction at 150 ° C. for 12 hours. The reaction solution was filtered and then lyophilized. Glucose (carbon concentration: 10%) and ultrapure water (10 cm ³⁾ were added to 8.4 g of the powder obtained by freeze-drying (about 12 hours), and calcined at 650 ° C. for 1 hr in a reducing atmosphere to obtain an olivine-type silicate compound. Obtained.

  Subsequently, the positive electrode of the lithium ion battery was produced using the obtained olivine type silicate compound. The obtained compound, ketjen black (conducting agent), polyvinylidene fluoride (binding agent) are mixed at a mixing ratio of 75:15:10, and N-methyl-2-pyrrolidone is added thereto and kneaded sufficiently. Thus, a positive electrode slurry was prepared. The positive electrode slurry was applied to a current collector made of an aluminum foil having a thickness of 20 μm using a coating machine, and vacuum dried at 80 ° C. for 12 hours. Thereafter, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.

Next, a coin-type lithium ion battery was constructed using the positive electrode. A lithium foil punched to φ15 mm was used for the negative electrode. As the electrolytic solution, a solution obtained by dissolving LIPF ₆ at a concentration of 1 mol / l in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 1 was used. As the separator, a known one such as a polymer porous film such as polypropylene was used. These battery components were assembled and housed in a conventional manner in an atmosphere having a dew point of −50 ° C. or lower to produce a coin type lithium ion battery (CR-2032).

  One cycle of charge and discharge at a constant current density was performed using the manufactured lithium ion battery. The charging conditions at this time were constant current and constant voltage charging with a current of 0.1 CA (33 mA / g) and a voltage of 4.5 V, and the discharging conditions were constant current discharging with a current of 0.1 CA and a final voltage of 1.5 V. All temperatures were 30 ° C. Table 1 shows the charge / discharge capacity of the battery constructed with the positive electrode material obtained in Example 1.

[Example 2]
Instead of the solvent used in Example 1, solvent containing the ultrapure water 17.5cm ³ and glycerin 20.0 cm ³ (glycerin content in the solvent: 53 wt%) except using the compound of Example 1 In the same manner as above, an olivine-type silicate compound was obtained. Next, a lithium ion battery was produced in the same manner as in Example 1, and charging and discharging were performed for one cycle. Table 1 shows the charge / discharge capacity of the battery constructed with the positive electrode material obtained in Example 2.

[Example 3]
Instead of the solvent used in Example 1, (the content of ethylene glycol in the solvent: 40% by mass) solvent containing the ultrapure water 22.5cm ³ and ethylene glycol 15.0 cm ³ except for using, implementation In the same manner as in Example 1, an olivine type silicate compound was obtained. Next, a lithium ion battery was produced in the same manner as in Example 1, and charging and discharging were performed for one cycle. Table 1 shows the charge / discharge capacity of the battery constructed from the positive electrode material obtained in Example 3.

[Comparative Example 1]
An olivine-type silicate compound was obtained in the same manner as in Example 1 except that only 37.5 cm ^{3 of} ultrapure water was used instead of the solvent used in Example 1. An olivine type silicate compound was obtained in the same manner as in Example 1. Next, a lithium ion battery was produced in the same manner as in Example 1, and charging and discharging were performed for one cycle. Table 1 shows the charge / discharge capacity of the battery constructed from the positive electrode material obtained in Comparative Example 1.

[Comparative Example 2]
Instead of the solvent used in Example 1, (the content of ethylene glycol in the solvent: 13% by mass) solvent containing the ultrapure water 32.5cm ³ and ethylene glycol 5.0 cm ³ except for using, implementation In the same manner as in Example 1, an olivine type silicate compound was obtained. Next, a lithium ion battery was produced in the same manner as in Example 1, and charging and discharging were performed for one cycle. Table 1 shows the charge / discharge capacity of the battery constructed with the positive electrode material obtained in Comparative Example 2.

  From the results in Table 1, it can be seen that the batteries obtained in Examples 1 to 3 have superior battery properties as compared with Comparative Examples 1 and 2.

Claims (4)

The following components (A), (B), (C) and (D):
(A) MSO ₄ (wherein, M is, Fe, Ni, Co, Al , Zn, V, showing the Zr or Mn) metallic sulphates or (R) in ₂ M (wherein represented by, R represents represents an organic acid residue, M is, Fe, Ni, Co, Al , Zn, V, Zr or an Mn) represented by an organic acid metal Shokushio, (B) a lithium compound,
(C) Silicate compound, and (D) A solvent containing 20 to 80% by mass of polyol and water is mixed, and then hydrothermally reacted at 100 to 200 ° C. to produce an olivine type silicate compound Method.   The method for producing an olivine-type silicate compound according to claim 1, wherein the polyol is a divalent alcohol. The polyol is at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, 1,4-butanediol, glycerin, trimethylolethane, trimethylolpropane, and 2-methylpropanetriol. Item 3. A method for producing an olivine-type silicate compound according to Item 1 or 2 .   A method for producing a positive electrode active material for a lithium ion battery, wherein carbon is supported on the olivine-type silicate compound according to any one of claims 1 to 3, followed by firing.