JP2019016530A - Manufacturing method of sulfide solid electrolyte fine particle - Google Patents

Abstract

To provide a manufacturing method of a sulfide solid electrolyte fine particle capable of suppressing aggregation of a fine particle material during a crystallization process.SOLUTION: There is provided a manufacturing method of a sulfide solid electrolyte fine particle having a preparation process for preparing a coarse particle material which is a sulfide solid electrolyte, an atomization process for atomizing the coarse particle material by a pulverization treatment to form a fine particle material, and a crystallization process for crystallizing the fine particle material by a heat treatment, in which the heat treatment is conducted with adding physical stimulation to the fine particle material in the crystallization process.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a method for producing sulfide solid electrolyte fine particles capable of suppressing aggregation of a fine particle material during a crystallization process.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, lithium batteries are attracting attention among various batteries from the viewpoint of high energy density.

  Since lithium batteries currently on the market use an electrolyte solution containing a flammable organic solvent, a safety device for preventing a temperature rise at the time of a short circuit and a structure for preventing a short circuit are required. In contrast, a lithium battery in which the electrolyte solution is replaced with a solid electrolyte layer and the battery is completely solid does not use a flammable organic solvent in the battery, and thus 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 made heretofore. For example, Patent Document 1 discloses that the coarse material contained in the slurry is finely divided by a preparation step of preparing a slurry containing a coarse particle material of a sulfide solid electrolyte and a dispersion medium and a pulverizer using a pulverization medium. A method for producing a sulfide solid electrolyte material, wherein the atomization step is performed in a temperature environment of 50 ° C. or higher. Is disclosed. Patent Document 1 discloses that the atomized sulfide solid electrolyte material is heat-treated to be crystallized.

JP, 2006-207421, A

  As the performance of batteries increases, sulfide solid electrolytes are required to further improve ion conductivity. As one of techniques for improving the ionic conductivity of the sulfide solid electrolyte, for example, as shown in Patent Document 1, there is a technique of crystallizing the sulfide solid electrolyte by heat treatment. 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.

  Inventors of the present disclosure, while conducting research in view of the above circumstances, when the finely divided sulfide solid electrolyte is crystallized by heat treatment, the finely divided materials are aggregated, and as a result The problem of increasing the particle size of the obtained fine particles was discovered. The main object of the present disclosure is to provide a method for producing sulfide solid electrolyte fine particles capable of suppressing aggregation of a fine particle material during a crystallization process.

  In order to solve the above-described problems, in the present disclosure, a fine particle that forms a fine particle material by preparing a coarse particle material that is a sulfide solid electrolyte and atomizing the coarse particle material by a pulverization process And a crystallization step of crystallizing the fine particle material by heat treatment, wherein in the crystallization step, the heat treatment is performed while applying physical stimulation to the fine particle material. A manufacturing method is provided.

  According to the present disclosure, agglomeration of the fine particle material can be suppressed by performing heat treatment while applying physical stimulation.

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

It is process drawing which shows an example of the manufacturing method of the sulfide solid electrolyte fine particle of this indication. It is a flowchart which shows an example of the manufacturing method of the sulfide solid electrolyte fine particle of this indication. It is a figure explaining the presumed mechanism of this indication. It is a schematic diagram which shows an example of a rotary baking furnace. It is a measurement result of the particle size distribution of the sulfide solid electrolyte fine particle of an Example, a reference example, and a comparative example. The measurement results of the average particle diameter in Comparative Examples and Examples (D _50). It is a measurement result of Li ion conductivity in a comparative example and an example.

Hereinafter, the details of the method for producing 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 sulfide solid electrolyte fine particles of the present disclosure. For example, as shown in FIG. 1 (a), the method for producing sulfide solid electrolyte fine particles of the present disclosure includes a preparation step of preparing a coarse particle material 1a that is a sulfide solid electrolyte, and FIGS. 1 (a) and 1 (b). As shown in FIG. 1C, the coarse material 1a is atomized by pulverization to form a fine material 1b. As shown in FIG. 1C, the fine material 1b is crystallized by heat treatment. And a crystallization step. In the crystallization process, heat treatment is performed while giving a physical stimulus X to the fine particle material 1b. In the crystallization step, by crystallizing the fine particle material 1b, as shown in FIG. 1 (d), crystallized sulfide solid electrolyte fine particles 1c can be obtained.

  FIG. 2 is a flowchart showing an example of a method for producing sulfide solid electrolyte fine particles of the present disclosure. As shown in FIG. 2, in the preparation step in the present disclosure, for example, the raw material composition for synthesizing the sulfide solid electrolyte is subjected to an amorphous treatment (for example, a ball mill (BM) treatment) to obtain coarse particles. A material (precursor) may be synthesized. In the atomization step in the present disclosure, for example, a coarse material may be atomized to form a fine material by performing a ball mill (BM) process as a pulverization process. Further, in the crystallization step in the present disclosure, the fine particle material may be crystallized by, for example, heat treatment using a rotary baking furnace.

  According to the present disclosure, agglomeration of the fine particle material can be suppressed by performing heat treatment while applying physical stimulation. As a result, sulfide solid electrolyte fine particles having a small average particle diameter can be obtained.

The inventors of the present disclosure say that when a fine particle material, which is a finely divided sulfide solid electrolyte, is crystallized by heat treatment, the fine particle materials are aggregated together, and as a result, the particle size of the obtained fine particles is increased. I knew the problem. As a specific example, it has been found that the particle size of the obtained fine particles is increased in any of the following production methods (1) and (2).
The production method (1) is a production method in which a coarse material, which is glass ceramics, is atomized as a sulfide solid electrolyte and then crystallized. Specifically, a coarse 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 and crystallized. Next, the coarse material is atomized by pulverization (for example, ball mill treatment) to form the fine material. Next, the fine particle 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 material which is sulfide glass as a sulfide solid electrolyte is atomized and then crystallized. Specifically, a coarse material (precursor) is synthesized by subjecting the raw material composition to an amorphous treatment (for example, a ball mill treatment). Next, the coarse material is atomized by pulverization (for example, ball mill treatment) to form the fine material. Next, the fine particle material is heat-treated and crystallized. By the above procedure, sulfide solid electrolyte fine particles are obtained.

The reason for increasing the particle size of the sulfide solid electrolyte fine particles 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. In the crystallization step, generally, the sulfide solid electrolyte is heat-treated in a state of being left in a heat treatment apparatus such as a firing furnace.
On the other hand, the atomized sulfide solid electrolyte (fine particle material, fine particles) easily aggregates, for example, within a range of 300 ° C. to 650 ° C., and the aggregated particles are easily necked (welded). 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 increases.

  For the above reasons, for example, in the recrystallization step in the manufacturing method (1) described above, and in the crystallization step in the manufacturing method (2) described above, the fine particle material aggregates and necks, It is estimated that the particle size of the sulfide solid electrolyte fine particles is increased.

  On the other hand, according to the present disclosure, aggregation of the fine particle material can be suppressed by performing a heat treatment while giving physical stimulation to the fine particle material in the crystallization step. The reason is presumed to be that the frequency of contact between the fine particle materials can be reduced by applying physical stimulation to the fine particle material. Moreover, in this indication, since aggregation of a fine particle material can be suppressed, as a result, the sulfide solid electrolyte fine particle with a small average particle diameter can be obtained. The reason is presumed to be that necking can be suppressed by suppressing aggregation of the fine particle material.

  Crystallization of a sulfide solid electrolyte is one of the effective methods for obtaining a sulfide solid electrolyte having high Li ion conductivity. However, the sulfide solid electrolyte is atomized while maintaining high Li ion conductivity (high Li ion). There is a situation where 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 diameter can be obtained.

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

1. Preparation Step The preparation step in the present disclosure is a step of preparing a coarse material that is a sulfide solid electrolyte.
In the present disclosure, at least a coarse material may be prepared, only a coarse material may be prepared, or a slurry containing the coarse material and a dispersion medium may be prepared. Note that the coarse-grained material and the slurry may be produced by themselves, or commercially available products may be purchased. Moreover, it is preferable that the said coarse grain material has Li ion conductivity.

The coarse-grained material is a sulfide solid electrolyte and usually contains Li element and S element. Furthermore, it is preferable that the coarse grain material contains at least one of P element, Ge element, Sn element and Si element. The coarse-grained material may contain at least one of O element and halogen element (eg, F element, Cl element, Br element, I element). Examples of the coarse-grained material include 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 , and 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-LiI, 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 S-B 2 S 3, Li 2 S-P 2 S 5 -Z m S n ( however, m, n is a positive number .Z is, Ge, Zn, one of the _{Ga.), Li 2 S-} GeS 2, L _{2 S-SiS 2 -Li 3 PO} 4, Li 2 S-SiS 2 -Li x MO y ( provided that, x, y is a positive number .M is, P, Si, Ge, B , Al, Ga, the In Any). The description of “Li ₂ S—P ₂ S ₅ ” means a material using 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, it is preferable that Li ₂ S peaks (2θ = 27.0 °, 31.2 °, 44.8 °, 53.1 °) are not observed in the XRD measurement using CuKα rays. Moreover, it is preferable that the said coarse grain material does not contain bridge | crosslinking sulfur. This is because the amount of hydrogen sulfide generated can be reduced. The bridging sulfur, for example, cross-linking sulfur Li ₂ S and _P 2 _{S 5} is reacted _{S 3} PS-PS 3 structure. Specifically, it is preferable that the peak of the S ₃ P—S—PS ₃ structure (peak in the vicinity of 402 cm ⁻¹ ) is not confirmed in the measurement of the Raman spectrum.

Examples of the shape of the coarse material include a spherical shape. The average particle size _{(D 50)} of the coarse material, for example, in the range of 5Myuemu～20myuemu. Moreover, Li ion conductivity in 25 degreeC of the said coarse-grained material is 1 * 10 < ^-5 > S / cm or more, for example, and it is preferable that it is 1 * 10 < ^-4 > S / cm or more.

The coarse-grained material may be sulfide glass or glass ceramics, but the former is preferable. The sulfide glass can be usually obtained by subjecting a raw material composition (for example, a mixture of Li ₂ S and P ₂ S ₅ ) to an amorphous treatment. Examples of the amorphous treatment include mechanical milling. The mechanical milling may be dry mechanical milling or wet mechanical milling, but the latter is preferred. It is because it can prevent that a raw material composition adheres to wall surfaces, such as a container. Glass ceramics can be obtained by heat-treating sulfide glass. The coarse 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. Moreover, when a coarse-grained material is a material which has crystallinity, it is preferable that a coarse-grained material has the crystal phase A mentioned later.

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

2. Atomization step The atomization step in the present disclosure is a step of forming a fine-grain material by atomizing the coarse-grain material by pulverization.

The pulverization method is not particularly limited as long as a coarse material can be atomized to obtain a desired fine material. Examples of the pulverization method include a method using a pulverization apparatus using a pulverization medium.
Examples of the grinding media include beads, balls, and blades. Examples of the material for the grinding media include ceramics, glass, and metal. Examples of the grinding device include a bead mill device and a ball mill device. The atomization conditions are adjusted as appropriate so that the desired sulfide solid electrolyte fine particles can be obtained.

  A rotating body that stirs the crushing medium (giving kinetic energy to the crushing medium) may be installed inside the container of the crushing device. The peripheral speed of the rotating body may be within a range of 8 m / s to 18 m / s, for example. The peripheral speed of the rotating body usually means the peripheral speed of the outermost periphery of the rotating body.

Further, the total pulverization energy imparted to the coarse material by the pulverizer is defined as follows.
The total milling energy ^{= (mv 2/2) nt} / s
(Where m is the weight (kg) per crushing medium, v is the peripheral speed (m / s) of the rotating body, n is the number of crushing media (pieces), and t is the processing time. (Second) and s is the weight (g) of the coarse-grained material)
The total pulverization energy may be within a range of, for example, 4.5 kJ · sec / g to 30 kJ · sec / g.

The shape of the fine particle material obtained in the atomization step may be, for example, a spherical shape such as a true spherical shape or an elliptical spherical shape, or may be a flat shape (scale shape). The average particle diameter (D ₅₀ ) of the fine particle material may be, for example, approximately the same as the average particle diameter (D ₅₀ ) of sulfide solid electrolyte fine particles described later.

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

  As a heat treatment method for performing heat treatment while giving physical stimulation to the fine particle material, for example, a heat treatment method using a firing furnace (rotary firing furnace) provided with a rotating device may be used, and a firing furnace provided with a stirring device. It may be a heat treatment method using a heat treatment method, or a heat treatment method using a firing furnace equipped with a vibration device. In the present disclosure, a heat treatment method using a rotary firing furnace is particularly preferable. This is because agglomeration between the fine particle materials can be suitably suppressed.

  Here, the rotary firing furnace used in the crystallization process will be described with reference to the drawings. FIG. 4 is a schematic sectional view showing an example of a rotary firing furnace. A rotary baking furnace 10 shown in FIG. 4 connects a baking furnace (for example, a tubular furnace) 11, a quartz tube 12 disposed in the baking furnace 11, a rotating unit 13, the quartz tube 12 and the rotating unit 13. And a rotating 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 φ5 mm to φ25 mm, for example. This is because the fine particle material can be heat-treated satisfactorily. Further, the number of rotations in the rotary baking furnace is, for example, more preferably 10 rpm or more, preferably 30 rpm or more, and more preferably 50 rpm or more. The number of rotations 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 particle material can be heat-treated at a target heat treatment temperature, and examples thereof include a tubular furnace.

The heat treatment temperature and 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. The heat treatment temperature may be, for example, 650 ° C. or less, 600 ° C. or less, or 550 ° C. or less.
The heat treatment time may be, for example, 30 minutes or longer, 1 hour or longer, or 2 hours or longer. The heat treatment time may be, for example, 24 hours or less, 12 hours or less, or 10 hours or less.
The rate of temperature rise (° C./min) from room temperature (25 ° C.) to the heat treatment time is not particularly limited.
The heat treatment is preferably performed in an inert gas atmosphere (eg, 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.
In the crystallization step, the fine particle material may be heat-treated within a 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 diameter (D ₅₀ ) of the sulfide solid electrolyte fine particles obtained by the present disclosure is, for example, 10 μm or less, and preferably 5 μm or less. On the other hand, the average particle diameter (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 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. The sulfide solid electrolyte fine particles obtained by the present disclosure are usually glass ceramics.

  In addition, the sulfide solid electrolyte fine particles obtained by the present disclosure have 2θ = 17.38 °, 20.18 °, 20.44 °, 23.56 °, 23.96 in the 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 fluctuate within a range of ± 0.50 ° or may fluctuate within a 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 one or more peak positions having a high peak intensity.

  On the other hand, as a crystal phase having lower Li ion conductivity than the 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 °, crystalline phases are known. Since the crystal lattice slightly changes depending on the material composition and the like, these peak positions may also move around ± 0.50 ° or around ± 0.30 °. The presence of the crystal phase B can be specified from one or more peak positions having a high peak intensity.

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. It is particularly preferred. Further, the value of I _B / I _A may be 0. In other words, the sulfide solid electrolyte fine particles may not have the crystal phase B. By increasing the proportion of the crystal phase A, it is possible to obtain sulfide solid electrolyte fine particles having high Li ion conductivity.

  Examples of the use of the sulfide solid electrolyte fine particles obtained by the present disclosure include a solid battery use. Further, in the present disclosure, there is provided 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, characterized in that the sulfide solid electrolyte fine particles described above are used for at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer. The solid battery may be a primary battery or a secondary battery, but is preferably a secondary battery. This is because it can be repeatedly charged and discharged and is useful, for example, as an in-vehicle battery.

  In addition, this indication is not limited to the said embodiment. The above-described embodiment is an exemplification, and the present invention has the same configuration as the technical idea described in the claims of the present disclosure and has the same function and effect regardless of the present embodiment. It is included in the technical scope of the disclosure.

  The present disclosure will be described more specifically with reference to examples.

[Example]
(Preparation of fine particle material)
Li ₂ S, P ₂ S ₅ and SnS ₂ were mixed to obtain a raw material composition. Mechanical milling was performed on the raw material composition to synthesize sulfide glass. The obtained sulfide glass and zirconia balls (φ1 mm) were put in a zirconia pot (volume 45 mL), and mechanical milling was performed to obtain a finely divided sulfide solid electrolyte (fine particle material).

(Heat treatment of fine-grained material in a rotary firing furnace)
500 mg of finely divided sulfide solid electrolyte (fine particle 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 tubular furnace. The number of revolutions was set to 70 rpm, the temperature was raised to 550 ° C. over 15 minutes, and held for 3 hours for firing. Thereafter, natural cooling was performed in the furnace to room temperature (about 25 ° C.) to obtain crystalline sulfide solid electrolyte fine particles.

[Comparative example]
(Heat treatment of fine particles by standing in a muffle furnace)
A fine particle material was prepared in the same manner as in the example.
500 mg of the obtained fine material was vacuum-sealed in a quartz tube as a powder. The quartz tube was allowed to stand in a muffle furnace, heated to 550 ° C. over 15 minutes, held for 3 hours and fired. Thereafter, natural cooling was performed in the furnace to room temperature (about 25 ° C.) to obtain crystalline sulfide solid electrolyte fine particles.

[Evaluation]
(Particle size distribution measurement)
The particle size distribution and average particle size (D ₅₀ ) of the sulfide solid electrolyte fine particles obtained in the examples and comparative examples were measured using a particle size distribution measuring device (manufactured by Microtrack Bell). As a reference example, the particle size distribution of the fine particle material before heat treatment was measured. FIG. 5 shows the particle size distribution measurement results of the examples, reference examples, and comparative examples, and FIG. 6 shows the average particle size (D ₅₀ ) results of the examples and comparative examples. As shown in FIG. 5, it was confirmed that the particle size distribution can be maintained in the example 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 diameter than the reference example were distributed. 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 diameter than those of the comparative examples were obtained.

(Li ion conductivity measurement)
The sulfide solid electrolyte fine particles obtained in the examples and comparative examples were compacted to produce pellets having an area of 1 cm and a thickness of about 0.5 mm. Li ion conduction is obtained by obtaining a resistance value of 100 kHz by AC impedance method using an impedance analyzer (VMP3, manufactured by Bio-logic) and correcting the resistance value with the thickness of the pellet. I asked for a 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 the comparative example was 3.2 mS / cm. In Examples, it was confirmed that Li ion conductivity was higher than that in 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.

DESCRIPTION OF SYMBOLS 1a ... Coarse-grain material 1b ... Fine-grain material 1c ... Sulfide solid electrolyte fine particle X ... Physical stimulation

Claims (1)

A preparation step of preparing a coarse-grained material that is a sulfide solid electrolyte;
By pulverizing the coarse material by pulverization, a finely pulverizing step for forming the fine pulverized material,
A crystallization step of crystallizing the fine particle material by heat treatment,
In the crystallization step, a method for producing sulfide solid electrolyte fine particles, wherein the heat treatment is performed while physically stimulating the fine particle material.

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