JP6946791B2 - Method for producing sulfide solid electrolyte fine particles - Google Patents

Description

The present disclosure relates to a method for producing sulfide solid electrolyte fine particles capable of suppressing aggregation of fine-grained materials during a crystallization step.

With the rapid spread of information-related devices such as personal computers, video cameras and mobile phones, and communication devices in recent years, the development of batteries used as their power sources has been emphasized. In addition, the automobile industry and the like are also developing high-output and high-capacity batteries for electric vehicles or hybrid vehicles. Currently, among various batteries, lithium batteries are attracting attention from the viewpoint of high energy density.

Since the lithium battery currently on the market uses an electrolytic solution containing a flammable organic solvent, it is necessary to attach a safety device that suppresses a temperature rise at the time of a short circuit and a structure for preventing the short circuit. On the other hand, a lithium battery in which the battery is completely solidified by replacing the electrolyte with a solid electrolyte layer does not use a flammable organic solvent in the battery, so that the safety device can be simplified.

Since the sulfide solid electrolyte has high lithium ion conductivity, it is useful for increasing the output of the battery, and various studies have been conducted conventionally. For example, Patent Document 1 describes fine particles of the coarse-grained material contained in the slurry by a preparatory step of preparing a coarse-grained material of a sulfide solid electrolyte and a slurry containing a dispersion medium and a crushing apparatus using a crushing medium. A method for producing a sulfide solid electrolyte material, which comprises a atomization step of forming a sulfide solid electrolyte material by forming the sulfide solid electrolyte material, and the atomization step is performed in a temperature environment of 50 ° C. or higher. Is disclosed. Further, Patent Document 1 discloses that the atomized sulfide solid electrolyte material is heat-treated to crystallize.

Japanese Unexamined Patent Publication No. 2016-207421

With the improvement of the performance of batteries, the sulfide solid electrolyte is required to further improve the ionic conductivity. As one of the methods for improving the ionic conductivity of the sulfide solid electrolyte, for example, as shown in Patent Document 1, there is a method of heat-treating the sulfide solid electrolyte to crystallize it. Further, from the viewpoint of increasing the filling rate of the electrode active material layer or the solid electrolyte layer, the sulfide solid electrolyte preferably has a small average particle size.

In conducting research in view of the above circumstances, the inventors of the present disclosure crystallize fine-grained materials, which are atomized sulfide solid electrolytes, by heat treatment, and the fine-grained materials aggregate with each other, resulting in agglomeration. , We found the problem that the particle size of the obtained fine particles becomes large. A main object of the present disclosure is to provide a method for producing sulfide solid electrolyte fine particles capable of suppressing aggregation of fine-grained materials during a crystallization step.

In order to solve the above-mentioned problems, in the present disclosure, in the present disclosure, fine particles forming a fine-grained material are formed by atomizing the coarse-grained material by a preparatory step of preparing a coarse-grained material which is a sulfide solid electrolyte and a pulverization treatment. A sulfide solid electrolyte fine particle which comprises a crystallization step and a crystallization step of crystallizing the fine particle material by heat treatment, and in the crystallization step, the heat treatment is performed while giving a physical stimulus to the fine particle material. Provide a manufacturing method.

According to the present disclosure, agglomeration of fine-grained materials can be suppressed by performing heat treatment while giving a physical stimulus.

The method for producing the sulfide solid electrolyte fine particles of the present disclosure has an effect that the aggregation of the fine particle material can be suppressed during the crystallization step.

It is a process drawing which shows an example of the manufacturing method of the sulfide solid electrolyte fine particle of this disclosure. It is a flowchart which shows an example of the manufacturing method of the sulfide solid electrolyte fine particle of this disclosure. It is a figure explaining the estimation mechanism of this disclosure. It is a schematic diagram which shows an example of a rotary firing furnace. It is a measurement result of the particle size distribution of the sulfide solid electrolyte fine particles of Examples, Reference Examples and Comparative Examples. It is a measurement result of the average particle diameter (D _{50) in a comparative example and an example.} It is a measurement result of Li ion conductivity in a comparative example and an example.

Hereinafter, the details of the method for producing the sulfide solid electrolyte fine particles of the present disclosure will be described.
FIG. 1 is a process diagram showing an example of a method for producing the sulfide solid electrolyte fine particles of the present disclosure. The method for producing the sulfide solid electrolyte fine particles of the present disclosure includes, for example, as shown in FIG. 1 (a), a preparatory step for preparing a coarse-grained material 1a which is a sulfide solid electrolyte, and FIGS. 1 (a) and 1 (b). ), The fine-grained material 1b is crystallized by a pulverization step of forming the fine-grained material 1b by atomizing the coarse-grained material 1a by a pulverization treatment and a heat treatment as shown in FIG. 1 (c). It comprises a crystallization step of crystallization. In the crystallization step, the fine particle material 1b is heat-treated while giving a physical stimulus X. In the crystallization step, by crystallizing the fine particle material 1b, crystallized sulfide solid electrolyte fine particles 1c can be obtained as shown in FIG. 1 (d).

FIG. 2 is a flowchart showing an example of the method for producing the sulfide solid electrolyte fine particles of the present disclosure. As shown in FIG. 2, in the preparatory step in the present disclosure, for example, the raw material composition for synthesizing a sulfide solid electrolyte is subjected to an amorphous treatment (for example, a ball mill (BM) treatment) to obtain coarse particles. The material (precursor) may be synthesized. Further, in the atomization step in the present disclosure, for example, a ball mill (BM) treatment may be performed as a pulverization treatment to atomize the coarse-grained material to form the fine-grained material. Further, in the crystallization step in the present disclosure, the fine-grained material may be crystallized by, for example, heat treatment using a rotary firing furnace.

According to the present disclosure, agglomeration of fine-grained materials can be suppressed by performing heat treatment while giving a physical stimulus. As a result, sulfide solid electrolyte fine particles having a small average particle size can be obtained.

The inventors of the present disclosure say that when a fine-grained material, which is a fine-grained sulfide solid electrolyte, is crystallized by heat treatment, the fine-grained materials aggregate with each other, and as a result, the particle size of the obtained fine particles becomes large. I found a problem. As a specific example, it was found that the particle size of the obtained fine particles was increased in any of the following production methods (1) and (2).
The production method (1) is a production method in which a coarse-grained material, which is a glass ceramic as a sulfide solid electrolyte, is atomized and then crystallized. Specifically, a coarse-grained material (precursor) is synthesized by subjecting the raw material composition to an amorphous treatment (for example, a ball mill treatment). Next, the coarse-grained material is heat-treated to crystallize. Next, a pulverization treatment (ball mill treatment as an example) is performed to atomize the coarse-grained material to form a fine-grained material. Next, the fine-grained material is heat-treated and recrystallized. By the above procedure, sulfide solid electrolyte fine particles are obtained.
The production method (2) is a production method in which a coarse-grained material, which is sulfide glass as a sulfide solid electrolyte, is atomized and then crystallized. Specifically, a coarse-grained material (precursor) is synthesized by subjecting the raw material composition to an amorphous treatment (for example, a ball mill treatment). Next, a pulverization treatment (ball mill treatment as an example) is performed to atomize the coarse-grained material to form a fine-grained material. Next, the fine-grained material is heat-treated to crystallize. By the above procedure, sulfide solid electrolyte fine particles are obtained.

The reason why the particle size of the sulfide solid electrolyte fine particles is increased by crystallizing the fine particle material by heat treatment is presumed as follows.
The crystallization temperature of the sulfide solid electrolyte is, for example, in the range of 300 ° C. to 650 ° C. Further, in the crystallization step, generally, the sulfide solid electrolyte is heat-treated in a state of being allowed to stand in a heat treatment apparatus such as a firing furnace.
On the other hand, the atomized sulfide solid electrolyte (particulate material, fine particles) is likely to aggregate in the range of, for example, 300 ° C. to 650 ° C., and the aggregated particles are likely to be necked (welded) to each other. That is, particle growth is likely to occur.
As shown in FIG. 3, when the crystallization temperature of the sulfide solid electrolyte and the particle growth temperature overlap, it is presumed that the particle size becomes large.

For the above reasons, for example, in the production method (1) described above, in the recrystallization step, and in the production method (2) described above, in the crystallization step, the fine-grained material aggregates and necks. It is presumed that the particle size of the sulfide solid electrolyte fine particles becomes large.

On the other hand, according to the present disclosure, agglomeration of the fine-grained material can be suppressed by performing the heat treatment while giving a physical stimulus to the fine-grained material in the crystallization step. It is presumed that the reason is that the frequency of contact between the fine-grained materials can be reduced by giving a physical stimulus to the fine-grained materials. Further, in the present disclosure, since the aggregation of the fine particle material can be suppressed, as a result, sulfide solid electrolyte fine particles having a small average particle size can be obtained. It is presumed that the reason is that necking can be suppressed by suppressing the aggregation of the fine particle material.

Crystallization of the sulfide solid electrolyte is one of the effective methods for obtaining a sulfide solid electrolyte having high Li ion conductivity, but atomization while maintaining high Li ion conductivity (high Li ion). There is a fact that it is difficult to achieve both conductivity and atomization). On the other hand, by applying the production method of the present disclosure, sulfide fine particles having high Li ion conductivity and a small average particle size can be obtained.

Hereinafter, the method for producing the sulfide solid electrolyte fine particles of the present disclosure will be described for each step.

1. 1. Preparation Step The preparation step in the present disclosure is a step of preparing a coarse-grained material which is a sulfide solid electrolyte.
In the present disclosure, at least a coarse-grained material may be prepared, only the coarse-grained material may be prepared, or a slurry containing the coarse-grained material and the dispersion medium may be prepared. The coarse-grained material and the slurry may be produced by themselves or may be purchased on the market. Further, the coarse-grained material preferably has Li ion conductivity.

The coarse-grained material is a sulfide solid electrolyte and usually has a Li element and an S element. Further, the coarse-grained material preferably contains at least one of P element, Ge element, Sn element and Si element. Further, the coarse-grained material may contain at least one of an O element and a halogen element (for example, F element, Cl element, Br element, and I element). As the coarse material, for _{example, Li 2 S-P 2 S} 5, Li 2 S-P 2 S 5 -GeS 2, Li 2 S-P 2 S 5 -SnS 2, Li 2 S-P 2 S 5 _{-SiS 2, Li 2 S-P} 2 S 5 -LiI, Li 2 S-P 2 S 5 -LiI-LiBr, Li 2 S-P 2 S 5 -Li 2 O, Li 2 S-P 2 S 5 - Li ₂ O-Li I, Li ₂ S-SiS ₂ , Li ₂ S-SiS _2- LiI, Li ₂ S-SiS _2- LiBr, Li ₂ S-SiS _2- LiCl, Li ₂ S-SiS _2- B ₂ S _3- LiI, Li ₂ S-SiS _2- P ₂ S _5- LiI, Li _{2 SB 2} S ₃ , Li _{2 SP 2} S _5- Z _m S _n (where m and n are positive numbers .Z is any of Ge, Zn, Ga.), Li ₂ S-GeS ₂ , Li ₂ S-SiS _{2 -Li 3} PO ₄ , Li ₂ S-SiS _{2 -Li x} MO _y (where x, y is a positive number, and M can be any of P, Si, Ge, B, Al, Ga, In, and the like. The above description of "Li ₂ SP ₂ S ₅ " means a material made of a raw material composition containing _{Li 2} S and P ₂ S _{5, and the same applies to other descriptions.}

The coarse-grained material preferably does not contain _{Li 2 S.} This is because the amount of hydrogen sulfide generated can be reduced. Specifically, in XRD measurement using a CuKα ray, the peak of _{Li 2 S (2θ = 27.0 °} , 31.2 °, 44.8 °, 53.1 °) it is preferred that is not observed. Further, the coarse-grained material preferably does not contain crosslinked sulfur. This is because the amount of hydrogen sulfide generated can be reduced. Examples of the cross-linked sulfur include cross-linked sulfur having an S ₃ P-S-PS ₃ structure formed _{by reacting Li 2} S and P ₂ S _5. Specifically, it is preferable that the peak _{of the S 3} PS- ₃ structure ( ^{peak near 402 cm -1} ) is not confirmed in the measurement of the Raman spectroscopic spectrum.

The shape of the coarse-grained material may be, for example, spherical. The average particle size (D ₅₀ ) of the coarse-grained material is, for example, in the range of 5 μm to 20 μm. The Li ion conductivity of the coarse-grained material at 25 ° C. is, for example, 1 × 10 ^-5 S / cm or more, and ^{preferably 1 × 10 -4} S / cm or more.

The coarse-grained material may be sulfide glass or glass ceramics, but the former is preferable. Sulfide glass can usually be obtained by amorphous treatment of a raw material composition (eg, _{a mixture of Li 2} S and P ₂ S _5). Examples of the amorphous treatment include mechanical milling. Further, the mechanical milling may be a dry mechanical milling or a wet mechanical milling, but the latter is preferable. This is because it is possible to prevent the raw material composition from sticking to the wall surface of the container or the like. Further, glass ceramics can be obtained by heat-treating sulfide glass. The coarse-grained material is not particularly limited as long as it is a sulfide solid electrolyte, and may be synthesized by, for example, a solid-phase reaction. When the coarse-grained material is a material having crystallinity, it is preferable that the coarse-grained material has a crystal phase A described later.

In the preparation step, a slurry containing the coarse-grained material and the dispersion medium may be prepared.
The dispersion medium preferably has an aprotic property that does not react with the coarse-grained material, and examples thereof include a polar aprotic liquid and a non-polar aprotic liquid.

2. Aluminization Step The atomization step in the present disclosure is a step of forming a fine particle material by atomizing the coarse particle material by a pulverization treatment.

The method of the pulverization treatment is not particularly limited as long as the coarse-grained material can be atomized and a desired fine-grained material can be obtained. As a method of crushing treatment, for example, a method of using a crushing device using a crushing medium can be mentioned.
Examples of the crushing medium include beads, balls, blades and the like. Examples of the material of the pulverized media include ceramics, glass, metal and the like. Examples of the crushing device include a bead mill device and a ball mill device. The conditions for atomization are appropriately adjusted so that the desired sulfide solid electrolyte fine particles can be obtained.

Inside the container of the crushing device, a rotating body that agitates the crushing media (gives kinetic energy to the crushing media) may be installed. The peripheral speed of the rotating body may be in the range of, for example, 8 m / s to 18 m / s. The peripheral speed of the rotating body usually means the peripheral speed of the outermost circumference of the rotating body.

In addition, the total crushing energy given to the coarse-grained material by the crushing device is defined as follows.
The total milling energy ^{= (mv 2/2) nt} / s
(In the formula, m is the weight (kg) per crushing medium, v is the peripheral speed (m / s) of the rotating body, n is the number (pieces) of the crushing media, and t is the processing time. (Seconds), where s is the weight (g) of the coarse grain material)
The total pulverization energy may be in the range of, for example, 4.5 kJ · sec / g to 30 kJ · sec / g.

The shape of the fine-grained material obtained in the atomization step may be, for example, a spherical shape such as a true sphere or an elliptical sphere, or a flat shape (scaly shape). The average particle size (D ₅₀ ) of the fine particle material may be, for example, about the same as _{the average particle size (D 50} ) of the sulfide solid electrolyte fine particles described later.

3. 3. Crystallization Step The crystallization step in the present disclosure is a step of crystallizing the fine-grained material by heat treatment.
In the crystallization step, the above heat treatment is performed while giving a physical stimulus to the fine particle material. In the crystallization step, when a physical stimulus is applied, the fine-grained material rotates (rolls) and vibrates, for example, so that the frequency of contact between the fine-grained materials is reduced and aggregation and necking are suppressed. Guessed.

The heat treatment method for heat-treating the fine-grained material while giving a physical stimulus may be, for example, a heat treatment method using a firing furnace equipped with a rotating device (rotary firing furnace), or a firing furnace equipped with a stirring device. It may be a heat treatment method using the above, or it may be a heat treatment method using a firing furnace equipped with a vibrating device. In the present disclosure, the heat treatment method using a rotary firing furnace is preferable. This is because agglomeration of fine-grained materials can be suitably suppressed.

Here, the rotary firing furnace used in the crystallization step will be described with reference to the drawings. FIG. 4 is a schematic cross-sectional view showing an example of a rotary firing furnace. The rotary firing furnace 10 shown in FIG. 4 connects a firing furnace (for example, a tubular furnace) 11, a quartz tube 12 arranged in the firing furnace 11, a rotating portion 13, and a quartz tube 12 and a rotating portion 13. It has a rotary rod 14.

In the heat treatment method using a rotary firing furnace, the inner diameter of the quartz tube is preferably in the range of, for example, φ5 mm to φ25 mm. This is because the fine-grained material can be satisfactorily heat-treated. Further, the rotation speed in the rotary firing furnace is, for example, more preferably 10 rpm or more, preferably 30 rpm or more, and further preferably 50 rpm or more. The rotation speed is, for example, preferably 500 rpm or less, more preferably 250 rpm or less, and particularly preferably 100 rpm or less.
The shape of the firing furnace used in the rotary firing furnace is not particularly limited as long as the fine-grained material can be heat-treated at the target heat treatment temperature, and examples thereof include a tubular furnace.

The heat treatment temperature and the heat treatment time in the crystallization step are appropriately adjusted according to the desired sulfide solid electrolyte fine particles. The heat treatment temperature may be, for example, 300 ° C. or higher, 350 ° C. or higher, or 400 ° C. or higher. Further, the heat treatment temperature may be, for example, 650 ° C. or lower, 600 ° C. or lower, or 550 ° C. or lower.
Further, the heat treatment time may be, for example, 30 minutes or more, 1 hour or more, or 2 hours or more. Further, the heat treatment time may be, for example, 24 hours or less, 12 hours or less, or 10 hours or less.
The heating rate (° C./min) from room temperature (25 ° C.) to the heat treatment time is not particularly limited.
The heat treatment is preferably carried out in an inert gas atmosphere (for example, Ar gas atmosphere) or a reduced pressure atmosphere (particularly in vacuum). This is because deterioration (for example, oxidation) of the sulfide solid electrolyte can be prevented.
Further, in the crystallization step, the fine particle material may be heat-treated within the range of 100 mg to 10 g.

In the present disclosure, sulfide solid electrolyte fine particles can be obtained by performing a crystallization step.

4. Sulfide solid electrolyte fine particles The average particle size (D ₅₀ ) of the sulfide solid electrolyte fine particles obtained in the present disclosure is, for example, 10 μm or less, and preferably 5 μm or less. On the other hand, the average particle size (D ₅₀ ) of the sulfide solid electrolyte fine particles is, for example, 0.01 μm or more.

Also, when the average particle size of the sulfide solid electrolyte fine particles obtained by the present disclosure _{(D 50)} and _{D A,} to an average particle size of the fine material _{(D 50)} and _{D B, D} A / _{D B,} for example It may be 2, 2 or less, 1.5 or less, 1.2 or less, or 0.95 or less.

The sulfide solid electrolyte fine particles obtained by the present disclosure may be spherical or flat. Further, the sulfide solid electrolyte fine particles obtained by the present disclosure are usually glass ceramics.

Further, the sulfide solid electrolyte fine particles obtained by the present disclosure are 2θ = 17.38 °, 20.18 °, 20.44 °, 23.56 °, 23.96 in X-ray diffraction measurement using CuKα ray. It is preferable to have a crystal phase having peaks at positions of °, 24.93 °, 26.96 °, 29.07 °, 29.58 °, 31.71 °, 32.66 ° and 33.39 °. Since the crystal lattice slightly changes depending on the material composition and the like, these peak positions may be changed in the range of ± 0.50 ° or may be changed in the range of ± 0.30 °. This crystal phase (referred to as crystal phase A) is known as a so-called LGPS type crystal phase. The presence of the crystal phase A can be identified from the peak positions of 1 or 2 or more having high peak intensities.

On the other hand, as a crystal phase having lower Li ion conductivity than crystal phase A (referred to as crystal phase B), 2θ = 17.46 °, 18.12 °, 19.99 °, 22.73 °, 25.72 °. , 27.33 °, 29.16 °, 29.78 ° peaks are known. Since the crystal lattice of these peak positions changes slightly depending on the material composition and the like, the peak positions may be changed in the range of ± 0.50 ° or may be changed in the range of ± 0.30 °. The presence of the crystal phase B can be identified from the peak positions of 1 or 2 or more having high peak intensities.

The diffraction intensity of the peak near 2 [Theta] = 29.58 ° in the crystal phase A and _{I A,} the diffraction intensity of the peak near 2 [Theta] = 27.33 ° in the crystalline phase B when the _{I B,} the I B / _{I A} The value is, for example, less than 0.50, preferably 0.45 or less, more preferably 0.25 or less, further preferably 0.15 or less, and 0.07 or less. Is particularly preferred. _The value of I B / _{I A} may be 0. In other words, the sulfide solid electrolyte fine particles do not have to have the crystal phase B. By increasing the proportion of the crystal phase A, sulfide solid electrolyte fine particles having high Li ion conductivity can be obtained.

Examples of applications of the sulfide solid electrolyte fine particles obtained by the present disclosure include solid-state battery applications. Further, in the present disclosure, it is a method for manufacturing a solid battery having a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer. It is also possible to provide a method for producing a solid battery, which comprises using the above-mentioned sulfide solid electrolyte fine particles for at least one of the above-mentioned positive electrode active material layer, the above-mentioned negative electrode active material layer and the above-mentioned solid electrolyte layer. The solid-state battery may be a primary battery or a secondary battery, but is preferably a secondary battery. This is because it can be charged and discharged repeatedly and is useful as an in-vehicle battery, for example.

The present disclosure is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same structure as the technical idea described in the claims of the present disclosure and exhibiting the same effect and effect is the present invention. Included in the technical scope of the disclosure.

The present disclosure will be described in more detail with reference to Examples below.

[Example]
(Preparation of fine grain material)
Li ₂ S, P ₂ S ₅ and SnS ₂ were mixed to obtain a raw material composition. The raw material composition was mechanically milled to synthesize sulfide glass. The obtained sulfide glass and zirconia balls (φ1 mm) were placed in a zirconia pot (volume 45 mL) and mechanically milled to obtain a atomized sulfide solid electrolyte (fine particle material).

(Heat treatment of fine particles in a rotary firing furnace)
500 mg of the atomized sulfide solid electrolyte (particulate material) was vacuum-sealed in a quartz tube (inner diameter φ15 mm) as a powder. A quartz tube was connected to a rotating rod and held in a tube furnace. The rotation speed was 70 rpm, the temperature was raised to 550 ° C. over 15 minutes, and the mixture was held for 3 hours for firing. Then, it was naturally cooled to room temperature (about 25 ° C.) in the furnace to obtain crystalline sulfide solid electrolyte fine particles.

[Comparison example]
(Heat treatment of fine particles by standing in a muffle furnace)
A fine-grained material was prepared in the same manner as in Examples.
500 mg of the obtained fine-grained material was vacuum-sealed in a quartz tube as a powder. This quartz tube was allowed to stand in a muffle furnace, heated to 550 ° C. over 15 minutes, held for 3 hours, and fired. After that, it was naturally cooled to room temperature (about 25 ° C.) in the furnace to obtain crystalline sulfide solid electrolyte fine particles.

[evaluation]
(Measurement of particle size distribution)
The particle size distribution and average particle size of the sulfide solid electrolyte fine particles obtained in Examples and Comparative Examples (D _50), was measured with a particle size distribution measuring apparatus (manufactured by Microtrac Bell). In addition, as a reference example, the particle size distribution of the fine particle material before the heat treatment was measured. The particle size distribution measurement results of Examples, Reference Examples and Comparative Examples are shown in FIG. 5, and the results of the average particle size (D ₅₀ ) of Examples and Comparative Examples are shown in FIG. As shown in FIG. 5, it was confirmed that in the examples, the particle size distribution can be maintained as compared with the fine particle material (reference example) before the heat treatment. On the other hand, in the comparative example, it was confirmed that a large number of particles having a larger particle size were distributed as compared with the reference example. Further, as shown in FIG. 6, the average particle size (D ₅₀ ) of the example was 0.83 μm, and the average particle size (D ₅₀ ) of the comparative example was 6.3 μm. In the examples, it was confirmed that sulfide solid electrolyte fine particles having a smaller average particle size than those of the comparative examples could be obtained.

(Measurement of Li ion conductivity)
The sulfide solid electrolyte fine particles obtained in Examples and Comparative Examples were compacted to prepare pellets having an area of 1 cm and a thickness of about 0.5 mm. For the obtained pellets, the resistance value of 100 kHz was obtained by the AC impedance method using an impedance analyzer (VMP3, manufactured by Bio-logic), and the resistance value was corrected by the thickness of the pellets to conduct Li ion conduction. I asked for the degree. The result is shown in FIG. As shown in FIG. 7, the Li ion conductivity of the example was 4.6 mS / cm, and that of the comparative example was 3.2 mS / cm. In the examples, it was confirmed that the Li ion conductivity was higher than that in the comparative examples.

From the above results, it was confirmed that in the examples, the average particle size can be reduced while achieving high Li ion conductivity.

1a ... Coarse grain material 1b ... Fine grain material 1c ... Sulfide solid electrolyte fine particles X ... Physical irritation

Claims (2)

A preparatory step of preparing a coarse-grained material which is a sulfide solid electrolyte using a raw material composition containing Li ₂ S, P ₂ S ₅ and Sn _{S 2.}
A pulverization step of forming a fine-grained material by atomizing the coarse-grained material by a pulverization treatment, and a fine-grained material.
A crystallization step of crystallizing the fine-grained material by heat treatment is provided.
In the crystallization step, the heat treatment is performed while giving a physical stimulus to the fine particle material.
The heat treatment is a process using a rotary firing furnace.
A method for producing sulfide solid electrolyte fine particles. Crystallization temperature before Symbol particulate material is in the range of 300 ° C. to 650 ° C.,
The method for producing sulfide solid electrolyte fine particles according to claim 1.

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