Powder manufacturing method

Abstract

The present invention provides a method for producing powder that allows for easy recovery of the slurry while maintaining the crystallinity of the solid electrolyte. [Solution] A liquid containing 65 wt% or more of a solvent having a dielectric constant of 2.6 or more and less than 5.0 at 20°C is mixed with a solid electrolyte, and the solid electrolyte is pulverized in this mixed state to produce a powder. Preferably, the solvent has a viscosity of 1 cP or less at 20°C. Preferably, the solvent has a solubility in water of 0.3 g / mL or less at 20°C. The solid electrolyte may contain Li. The solid electrolyte may be an oxide, and the oxide may have a garnet-type crystal structure containing Li, La, and Zr.

Description

Technical Field

[0001] The present invention relates to a method for producing a powder of a solid electrolyte.

Background Art

[0002] Prior art for producing a powder of a solid electrolyte by pulverizing the solid electrolyte in a slurry state in which a strongly hydrophobic organic solvent and the solid electrolyte are mixed is disclosed in Patent Document 1.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When pulverizing a solid electrolyte in a strongly hydrophobic organic solvent as in the prior art, elution of the elements constituting the solid electrolyte is small, so the crystallinity of the solid electrolyte is likely to be maintained. However, there is a problem that the slurry adheres to the container and media used for pulverization, and it is difficult to recover the slurry containing the powder.

[0005] The present invention has been made to solve this problem, and an object thereof is to provide a method for producing a powder that can easily recover a slurry while maintaining the crystallinity of a solid electrolyte.

Means for Solving the Problems

[0006] A first aspect for achieving this object is to produce a powder by pulverizing a solid electrolyte in a state where a liquid containing 65 wt% or more of a solvent having a relative permittivity at 20 °C of 2.6 or more and less than 5.0 and the solid electrolyte are mixed.

[0007] A second aspect is that, in the first aspect, the solvent has a viscosity at 20 °C of 1 cP or less. [[ID=五十一]]

[0008] In the third embodiment, the solvent has a solubility in water at 20°C of 0.3 g / mL or less, as in the first or second embodiment.

[0009] The fourth embodiment is the first or second embodiment, wherein the solvent has a solubility in water at 20°C of 0.1 g / mL or less.

[0010] The fifth aspect is that, in any of the first to fourth aspects, the solid electrolyte includes Li.

[0011] The sixth aspect is that, in any of the first to fifth aspects, the solid electrolyte is an oxide.

[0012] In the seventh embodiment, the oxide has a garnet-type crystal structure containing Li, La, and Zr, as in the sixth embodiment.

[0013] The eighth aspect is the same as the seventh aspect, wherein the oxide includes Mg and Sr. [Effects of the Invention]

[0014] According to the present invention, the solid electrolyte is pulverized in a slurry state obtained by mixing a liquid containing 65 wt% or more of a solvent having a relative permittivity of 2.6 or more and less than 5.0 at 20°C with the solid electrolyte. This makes it possible to easily recover the slurry while maintaining the crystallinity of the solid electrolyte. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing the crystal structure of a garnet-type crystal. [Modes for carrying out the invention]

[0016] Preferred embodiments of the present invention will be described below. The present invention is not limited to the following embodiments, and various modifications are possible without altering the spirit of the invention.

[0017] The solid electrolyte in this embodiment is an inorganic substance, and examples thereof include one or more selected from sulfide-based, oxide-based, hydride-based, and halide-based substances. The solid electrolyte may be crystalline or amorphous. Examples of the sulfide-based solid electrolyte include crystalline thiolysicon type, Li 10 GeP2S 12 type, argyrodite type, Li7P3S 11 type, and glass or glass-ceramic systems typified by Li2S-P2S5. Examples of the hydride-based solid electrolyte include solid solutions of LiBH4 and lithium halide compounds (LiI, LiBr, LiCl) and lithium amide (LiNH2). An example of the halide-based solid electrolyte is Li3YCl6.

[0018] Examples of the oxide-based solid electrolyte include crystalline and amorphous substances such as NASICON-based materials, LISICON-based materials, oxides having a perovskite structure, and oxides having a garnet structure. The NASICON-based material is a material represented by the general formula A x M2(TO4)3. Examples of A include Na and Li, examples of M include Zr, Ti, V, Mn, Cr, Fe, Ni, Al, and Ge, and examples of T include P, Si, and As. For example, Na3V2(PO4)3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Ge x Ti 2-x (PO4)3 can be cited.

[0019] Examples of the LISICON-based material include Li 4-2x Zn x GeO4(0≦x≦1). Examples of the oxide having a perovskite structure include Li x La (1-x) / 3 NbO3, La 2 / 3-X Li 3X TiO3(0≦x≦1). The crystal structure of the garnet type oxide is represented by the general formula C3A2B3O 12 . Oxides having a garnet structure are preferable because they have excellent reducibility resistance to lithium metal.

[0020] Figure 1 schematically shows a garnet-type crystal structure. In the garnet-type crystal structure, the C site Sc is dodecahedral in coordination with the oxygen atom Oa, the A site Sa is octahedral in coordination with the oxygen atom Oa, and the B site Sb is tetrahedral in coordination with the oxygen atom Oa. In the garnet-type crystal structure, Li can be present in the void V, which is the site where the oxygen atom Oa is octahedral in coordination. The void V is, for example, the area between B site Sb1 and B site Sb2. The Li present in void V is octahedral in coordination with the oxygen atom Oa that constitutes an octahedron including the tetrahedral face Fb1 forming B site Sb1 and the tetrahedral face Fb2 forming B site Sb2. For example, Li7La3Zr2O 12 In a garnet-type solid electrolyte with this composition, La may occupy the C site Sc, Zr may occupy the A site Sa, and Li may occupy the B site Sb and the void V.

[0021] Garnet-type solid electrolytes are found in the CSD (Cambridge Structural Database) X-ray diffraction file No. 422259 (Li7La3Zr2O 12 It has an XRD pattern similar to ). In garnet-type solid electrolytes, various elements are substituted. For example, Ca, Sr, Ba, etc. are substituted at the C site, Nb, Ta, Sn, Hf, etc. are substituted at the A site, and Al, Ga, etc. are substituted at the B site. The amount of lithium changes due to elemental substitution, and the ionic conductivity changes as the arrangement, occupancy rate, and occupancy sites of lithium ions in the crystal structure change. The diffraction angle and intensity ratio may differ compared to No. 422259 due to elemental substitution.

[0022] Garnet-type solid electrolytes are typically Li7La3Zr2O 12 Examples include: The solid electrolyte may have some of its constituent elements substituted with other elements, or it may have trace amounts of other elements added without substituting any constituent elements. Examples of other elements include at least one element selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Ga, Sr, Y, Nb, Sn, Sb, Ba, Hf, Ta, W, Bi, Rb, and lanthanides (excluding La).

[0023] Solid electrolytes include, for example, Li6La3Zr 1.5 W 0.5 O 12 ,Li 6.15 La3Zr 1.75 Ta 0.25 Al 0.2 O 12 ,Li 6.15 La3Zr 1.75 Ta 0.25 Ga 0.2 O 12 ,Li 6.25 La3Zr2Ga 0.25 O 12 ,Li 6.4 La3Zr 1.4 Ta 0.6 O 12 ,Li 6.5 La3Zr 1.75 Te 0.25 O 12 ,Li 6.75 La3Zr 1.75 Nb 0.25 O 12 ,Li 6.9 La3Zr 1.675 Ta 0.289 Bi 0.036 O 12 ,Li 6.46 Ga 0.23 La3Zr 1.85 Y 0.15 O 12 ,Li 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 ,Li 7.05 La 3.00 Zr 1.95 Gd 0.05 O 12 ,Li 6.20 Ba 0.30 La 2.95 Rb 0.05 Zr2O 12 and the like can be mentioned.

[0024] The solid electrolyte is preferably one that contains Mg and at least one of element A (where A is at least one element selected from the group consisting of Ca, Sr, and Ba), and the molar ratio of each element satisfies all of (1) to (3) below, or one that contains both Mg and element A, and the molar ratio of each element satisfies all of (4) to (6) below. Element A is preferably Sr in order to increase the ionic conductivity of the solid electrolyte. (1) 1.33 ≤ Li / (La+A) ≤ 3 (2) 0 ≤ Mg / (La+A) ≤ 0.5 (3) 0 ≤ A / (La + A) ≤ 0.67 (4) 2.0 ≤ Li / (La+A) ≤ 2.6 (5) 0.01 ≤ Mg / (La+A) ≤ 0.14 (6) 0.04 ≤ A / (La + A) ≤ 0.17

[0025] Solid electrolyte powders can be produced, for example, by the following method: First, a mixture of starting materials is prepared, consisting of metal salts such as oxides, hydroxides, carbonates, and oxalates containing the metal elements that make up the solid electrolyte. The mixture can be prepared by solid-phase, liquid-phase, or gas-phase methods without limitation. The means of mixing the starting materials can be wet or dry, without limitation.

[0026] The mixture is prepared so that the proportion of metal elements matches or approximates the stoichiometric composition to the extent that the desired solid electrolyte is obtained. If the mixture contains certain metal elements that are easily lost during calcination, such as lithium, those metal elements may be present in excess relative to the stoichiometric composition.

[0027] Next, the mixture is calcined. The mixture is generally calcined two or more times. The main purpose of the first calcination (hereinafter referred to as "primary calcination") is the thermal decomposition of the starting materials. Primary calcination facilitates the formation of a solid electrolyte structure in the second calcination (hereinafter referred to as "secondary calcination"). The calcined product after primary calcination may already have a solid electrolyte structure. Performing primary and secondary calcination is just one example, and the number of calcinations is not limited to two. The number of calcinations may be more or less than two.

[0028] For garnet-type solid electrolytes, the primary calcination temperature is typically between 850°C and 1150°C. The primary calcination may include steps of calcination at lower temperatures and steps of calcination at higher temperatures within this temperature range. Before proceeding to the next calcination step, the calcined materials from each step may be crushed and mixed. It is desirable to crush the calcined materials dry. The primary calcination time is typically between 10 and 15 hours at the set maximum temperature.

[0029] The primary purpose of secondary firing is the synthesis of the solid electrolyte. For garnet-type solid electrolytes, the secondary firing temperature is typically between 1100°C and 1250°C. The secondary firing time is typically between 10 and 20 hours at the set maximum temperature.

[0030] Solid electrolyte powder is produced by pulverizing the calcined material (solid electrolyte). The pulverization of the solid electrolyte is carried out in a slurry state, which is a mixture of the solid electrolyte and liquid. The pulverization process involves placing the solid electrolyte, liquid, and media such as beads into a container, applying energy to the media, and crushing the solid electrolyte dispersed in the liquid through collisions and shearing of the media. Methods of pulverization include media-agitating mills such as planetary mills and bead mills, which mechanically agitate the media to pulverize the solid electrolyte.

[0031] The liquid contains 65 wt% or more of a solvent whose relative permittivity at 20°C is 2.6 or more and less than 5.0. Examples of such solvents include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propionic acid, cyclopentyl methyl ether (CPME), and chloroform. The relative permittivity of the solvent is calculated by measuring the dielectric constant at a test frequency of 10 kHz using a dielectric constant meter according to the method specified in JIS C2138:2007.

[0032] As the dielectric constant of a solvent decreases, it becomes more hydrophobic (e.g., a nonpolar solvent), which worsens the dispersibility of the powder. This makes the slurry more likely to adhere to the containers and media used for grinding, and makes it difficult to recover the slurry containing the powder. Conversely, as the dielectric constant of a solvent increases, it becomes more hydrophilic (e.g., a polar solvent), which makes solvation more likely. This makes it easier for elements constituting the solid electrolyte to dissolve into the solvent, and the crystalline phase of the solid electrolyte tends to change. In particular, when the solid electrolyte contains lithium, the amount of lithium that dissolves in the solvent increases, making the crystalline phase of the solid electrolyte more susceptible to change.

[0033] In contrast, by using a solvent with a dielectric constant of 2.6 or higher and less than 5.0 at 20°C for grinding, the amount of slurry adhering to the containers and media used for grinding is reduced, making it easier to recover the slurry containing the powder. Furthermore, the leaching of elements constituting the solid electrolyte is reduced, resulting in less change in the crystalline phase due to grinding, and thus preserving the crystallinity of the solid electrolyte.

[0034] The proportion of one or more solvents with a dielectric constant of 2.6 or more and less than 5.0 to the liquid is 65 wt% or more and 100 wt% or less. This is to ensure the dispersibility of the powder during grinding and to reduce elution into the liquid. When the proportion of solvent to the liquid is 65 wt% or more and less than 100 wt%, examples of substances other than the solvent contained in the liquid include solvents with a dielectric constant of less than 2.6 and solvents with a dielectric constant of more than 5.0. Examples of solvents with a dielectric constant of less than 2.6 include non-aqueous solvents such as hexane, fluorinate, and toluene. Examples of solvents with a dielectric constant of more than 5.0 include non-aqueous solvents such as butyl acetate, methyl ethyl ketone (MEK), propylene carbonate (PC), and ethylene carbonate (EC).

[0035] The viscosity of the solvent at 20°C is preferably 1 cP or less, provided that the dielectric constant is between 2.6 and 5.0. This is because it reduces the energy absorbed by the media during grinding, allowing the solid electrolyte to be crushed into smaller particles even with less energy applied to the media, thus enabling the production of powders with a particle size distribution, for example, a median diameter of less than 1.0 μm. The viscosity of the solvent is measured using a vibrating viscometer according to the method specified in JIS Z8803:2011.

[0036] If the water content of the liquid used during grinding increases, the elution of elements constituting the solid electrolyte increases, which may reduce the crystallinity of the solid electrolyte. Therefore, grinding is usually performed in an atmosphere with a low dew point (for example, a dew point of around -50°C to -60°C). The solubility of the solvent contained in the liquid, having a dielectric constant of 2.6 or more and less than 5.0, in water at 20°C is preferably less than 1.0 g / mL, more preferably 0.3 g / mL or less, and particularly preferably 0.1 g / mL or less. This is because the hygroscopicity of the solvent can be reduced, so the water content of the liquid can be reduced without excessively lowering the dew point of the atmosphere during grinding (for example, a dew point of around -20°C to -30°C). The solubility of the solvent in water is measured using a Karl Fischer moisture meter, and the fully saturated solvent is measured by the Karl Fischer coulometric titration method specified in JIS K0113:2005.

[0037] The resulting solid electrolyte powder can be used as a material for electrochemical elements such as energy storage devices like secondary batteries and electrochemical capacitors, and electrochemical sensors like gas sensors. Examples of electrochemical capacitors include redox capacitors that utilize redox reactions and hybrid capacitors, which are asymmetric cells combining electric double-layer capacitors with solid electrolytes.

[0038] A molded body can be created by applying pressure to a powder or by applying a slurry containing the powder, and this molded body can be used as part of an electrochemical element. A sintered body can also be created by firing the molded body, and this sintered body can also be used as part of an electrochemical element. The sintered body may be processed as needed. Examples of processing include polishing, grinding, and cutting. [Examples]

[0039] The present invention will be described in more detail by reference to examples, but the present invention is not limited to these examples.

[0040] (Preparation of solid electrolytes) Li 6.95 Mg 0.15 La 2.75 Sr 0.25 Zr 2.0 O 12 Li2CO3, MgO, La(OH)3, SrCO3, and ZrO2 were weighed accordingly. Li2CO3 was kept in excess by approximately 15 mol% in elemental terms, considering the volatilization of Li during calcination. The weighed raw materials and ethanol were placed in a nylon pot along with zirconia balls and ground and mixed in a ball mill for 15 hours. After drying the slurry removed from the pot, it was placed on an MgO plate and calcined at 1200°C for 10 hours. The calcined powder was ground in a mortar and pestle, and the material that passed through a 250 μm mesh was obtained as calcined powder. The calcined powder was placed in an MgO sieve and further calcined at 1100°C for 4 hours to obtain a calcined product. The calcined product was dry-ground in a mortar and pestle, and the material that passed through a 250 μm mesh was collected to obtain a solid electrolyte (hereinafter referred to as "LLZ").

[0041] The X-ray diffraction pattern of LLZ was obtained by powder X-ray diffraction. A RIGAK RINT TTR3 powder X-ray diffractometer was used, and the diffraction intensity was plotted at 0.02° intervals in the range of 2θ = 10°-80°. The lattice constant of the main phase of LLZ calculated from the X-ray diffraction pattern was less than 13.00 Å, so the main phase of LLZ was identified as a cubic crystal, which is said to have high lithium-ion conductivity.

[0042] (Grinding of solid electrolytes) As solvents, hexane, fluorinated inert liquid Fluorinert®, toluene, diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propionic acid, cyclopentyl methyl ether (CPME), chloroform, butyl acetate, methyl ethyl ketone (MEK), propylene carbonate (PC), and ethylene carbonate (EC) were prepared. Not only solvents with a water content of less than 10 ppm (mass concentration) were prepared, but also solvents that had absorbed moisture to 10 ppm to less than 100 ppm and 100 ppm to less than 1000 ppm.

[0043] In an atmosphere with a dew point of -50°C, LLZ, solvent, and media (3 mm diameter beads) were placed in a planetary mill container, and the planetary mill was operated at a rotation speed of 600 rpm for 6 hours to grind the LLZ. After removing the slurry from the container, the solvent contained in the slurry was evaporated to obtain the powders for samples No. 1-14. In the grinding of samples No. 1-14, the material and size of the container, the material of the media, and the amounts of LLZ, solvent, and media placed in the container were kept constant.

[0044] Table 1 shows the names of the solvents used for grinding samples No. 1-14, the dielectric constant of the solvent at 20°C, the viscosity of the solvent at 20°C, and the solubility of the solvent in water at 20°C. The dielectric constant was determined at a test frequency of 10 kHz, and the viscosity of the solvent was measured using a vibrating viscometer VM-10A (Sekonic Corporation).

[0045] The solvent for Sample No. 10 was a mixed solvent consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylene carbonate (EC), and propylene carbonate (PC) in a mass ratio of 35:20:10:20:15. Since the dielectric constant, viscosity, and solubility of each individual solvent constituting the mixed solvent were known, the dielectric constant, viscosity, and solubility of the mixed solvent were not measured.

[0046] [Table 1]

[0047] (evaluation) In samples No. 1-14, the degree of adhesion of the slurry to the container and media was evaluated after removing the slurry from the container and separating the slurry from the media. Samples with no adhesion to the container or media were rated A, while samples where the slurry adhered to the container or media and recovery was difficult were rated C. The results are shown in the adhesion column of Table 1.

[0048] The particle size distribution of powders in samples No. 1-14 was measured by laser diffraction and scattering. The median diameter (D) of the powder was measured. 50 A was evaluated as A if the median diameter was 0.5 μm or less, B if the median diameter was greater than 0.5 μm but less than 1.0 μm, and C if the median diameter was 1.0 μm or greater. The results are shown in Table 1, D. 50 I wrote it in the column.

[0049] X-ray diffraction patterns of powders No. 1-14 were obtained using powder X-ray diffraction (Rigaku RINT TTR3). The lattice constant of the LLZ main phase was calculated from the X-ray diffraction patterns. Samples with a lattice constant of less than 13.00 Å were evaluated as A (main phase is cubic), and samples with a lattice constant of 13.00 Å or more were evaluated as C (main phase is tetragonal). The results are shown in the lattice constant column of Table 1.

[0050] Based on the above evaluation, it is fixed, D 50 And if all evaluations of the lattice constants were A, it was judged as A. Fixation, D 50 Furthermore, even if the lattice constant evaluation for a moisture content of less than 10 ppm was A, if the evaluation for other lattice constants was C, it was judged as B. (Fixation, D) 50 If either the lattice constant or the moisture content was less than 10 ppm was rated as C, the result was determined to be C. The results of the determination are recorded in the "Determination" column of Table 1.

[0051] Samples No. 4-9, which were ground using a solvent with a dielectric constant of 2.6 or more and less than 5.0 at 20°C, and Sample No. 10, which was ground using a liquid containing 65 wt% of a solvent with a dielectric constant of 2.6 or more and less than 5.0 at 20°C, received a rating of A or B. However, samples No. 1-3, which were ground using a solvent with a dielectric constant of less than 2.6 at 20°C, received a rating of C for adhesion. Furthermore, samples No. 11-14, which were ground using a solvent with a dielectric constant of 5.0 or more at 20°C, received a rating of C for lattice constant with a water content of less than 10 ppm. The examples demonstrate that grinding LLZ using a liquid (non-aqueous solvent) containing 65 wt% or more of a solvent with a dielectric constant of 2.6 or more and less than 5.0 at 20°C reduces the slurry that adheres to containers and media, and maintains the crystallinity of LLZ.

[0052] Of the samples No. 4-10 that received a rating of A or B, samples No. 4-6 and 8-10, which were pulverized using a solvent with a viscosity of 1.00 cP or less at 20°C, were rated D. 50 The evaluation was A. However, sample No. 7, which was pulverized using a solvent with a viscosity of 1.02 cP at 20°C, was D. 50 The evaluation was B. It is presumed that in samples No. 4-6 and 8-10, the energy loss due to the solvent was reduced because a solvent with a viscosity of 1.00 cP or less was used, allowing the solid electrolyte to be broken down into smaller pieces by the energy of the media.

[0053] Of samples No. 4-10, samples No. 4-6 and 8-10, which were ground using a solvent with a solubility in water of less than 1.0 g / L (especially 0.3 g / mL or less) at 20°C, received a lattice constant evaluation of A when the water content of the solvent was between 10 ppm and 100 ppm. However, sample No. 7, which was ground using propionic acid with a solubility in water of 1.0 g / L at 20°C, received a lattice constant evaluation of C when the water content of the solvent was between 10 ppm and 100 ppm. The solvents for samples No. 4-6 and 8-10 had a solubility in water of 0.3 g / mL or less, while the propionic acid solvent for sample No. 7 had a solubility in water of 1.0 g / mL. Therefore, it is presumed that lithium ions of LLZ dissolved in the water dissolved in the propionic acid, resulting in a decrease in the crystallinity of LLZ.

[0054] Of samples No. 4-6 and 8-10, samples No. 4, 5, and 8-10, which were ground using a solvent with a solubility in water of 0.10 g / L or less at 20°C, received a lattice constant evaluation of A when the solvent's water content was between 100 ppm and less than 1000 ppm. However, sample No. 6, which was ground using a solvent with a solubility in water of approximately 0.14 g / L at 20°C, received a lattice constant evaluation of C when the solvent's water content was between 100 ppm and less than 1000 ppm. While the solvents for samples No. 4, 5, and 8-10 had a solubility in water of 0.10 g / mL or less, the DMC solvent for sample No. 6 had a solubility in water of 0.13 g / mL. Therefore, it is presumed that lithium ions of LLZ dissolved in the water dissolved in DMC, resulting in a decrease in the crystallinity of LLZ.

[0055] The solvents in samples No. 4-6 and 8-10 had a solubility of 0.3 g / mL in water at 20°C, and in particular, the solvents in samples No. 4, 5, and 8-10 had a solubility of 0.10 g / mL or less at 20°C. Since the hygroscopicity of the solvents can be reduced, it was found that the effect of maintaining the crystallinity of LLZ is greater when the water content of the solvent is 10 ppm or higher, especially when the water content is 20 ppm or higher. Furthermore, since the hygroscopicity of the solvent can be reduced, it is not necessary to set the dew point of the atmosphere during grinding to a low dew point of around -50°C to -60°C, and it is estimated that the crystallinity of LLZ can be maintained even when grinding in a mild atmosphere with a dew point of around -20°C to -30°C.

Claims

1. A method for producing a powder of a solid electrolyte, A method for producing a powder, comprising mixing the solid electrolyte with a liquid containing 65 wt% or more of a solvent having a relative permittivity of 2.6 or more and less than 5.0 at 20°C, and then pulverizing the solid electrolyte.

2. The method for producing the powder according to claim 1, wherein the solvent has a viscosity of 1 cP or less at 20°C.

3. The method for producing the powder according to claim 1, wherein the solvent has a solubility in water of 0.3 g / mL or less at 20°C.

4. The method for producing the powder according to claim 1, wherein the solvent has a solubility in water at 20°C of 0.1 g / mL or less.

5. The method for producing the powder according to any one of claims 1 to 4, wherein the solid electrolyte comprises Li.

6. The method for producing the powder according to any one of claims 1 to 4, wherein the solid electrolyte is an oxide.

7. The method for producing the powder according to claim 6, wherein the oxide has a garnet-type crystalline structure containing Li, La, and Zr.

8. The method for producing the powder according to claim 7, wherein the oxide comprises Mg and Sr.

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