METHOD OF MANUFACTURING SULFIDE-BASED INORGANIC SOLID ELECTROLYTE MATERIAL

Abstract

Provided is a method of manufacturing a sulfide-based inorganic solid electrolyte material including Li, P, and S as constituent elements, the method including: a preparation step of preparing a raw material inorganic composition (A) including at least lithium sulfide, phosphorus sulfide, and a crystal nucleating agent; and a vitrification step of mechanically processing the raw material inorganic composition (A) to vitrify the raw material inorganic composition (A).

Claims

1. A method of manufacturing a sulfide-based inorganic solid electrolyte material including Li, P, and S as constituent elements, the method comprising: a preparation step of preparing a raw material inorganic composition (A) including at least lithium sulfide, phosphorus sulfide, and a crystal nucleating agent; and a vitrification step of mechanically processing the raw material inorganic composition (A) to vitrify the raw material inorganic composition (A).

2. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 1, wherein the crystal nucleating agent includes an inorganic solid electrolyte material.

3. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 2, wherein the crystal nucleating agent includes a sulfide-based inorganic solid electrolyte material including Li, P, and S as constituent elements.

4. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 3, wherein a molar ratio (Li/P) of a content of Li to a content of P in the sulfide-based inorganic solid electrolyte material as the crystal nucleating agent is 1.0 or higher and 10.0 or lower, and a molar ratio (S/P) of a content of S to the content of P in the sulfide-based inorganic solid electrolyte material as the crystal nucleating agent is 1.0 or higher and 10.0 or lower.

5. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 1, a content of the crystal nucleating agent in the raw material inorganic composition (A) is 5 mass % or higher and 60 mass % or lower.

6. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 1, wherein the mechanical process in the vitrification step includes a mechanochemical process.

7. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 1, wherein the mechanical process in the vitrification step is performed in a dry condition.

8. The method of manufacturing a sulfide-based inorganic solid electrolyte material according to claim 1, further comprising: a crystallization step of heating an inorganic composition (B) obtained after the vitrification step to crystallize at least a part of the inorganic composition (B).

Description

EXAMPLES

[0085] Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples. However, the present invention is not limited to these Examples and Comparative Examples.

[0086] <Evaluation Method>

[0087] First, an evaluation method in the following Examples and Comparative Examples will be described.

[0088] (1) Measurement of Lithium Ionic Conductivity

[0089] In each of the sulfide-based inorganic solid electrolyte material obtained in each of Examples and Comparative Examples, the lithium ionic conductivity was measured using an alternating current impedance method.

[0090] For the measurement of the lithium ionic conductivity, a potentiostat/galvanostat SP-300 (manufactured by Bio-Logic Sciences Instruments) was used. The size of the sample was diameter: 9.5 mm and thickness: 1.2, 2.0 mm. Measurement conditions were applied voltage: 10 mV, measurement temperature: 27.0° C., and measurement frequency range: 0.1 Hz to 7 MHz, and electrode: Li foil.

[0091] Here, 150 mg of the powdery sulfide-based inorganic solid electrolyte material obtained in each of Examples and Comparative Examples was pressed using a press machine at 270 MPa for 10 minutes, and the plate-shaped sulfide-based inorganic solid electrolyte material having a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was obtained and used as the sample for the measurement of the lithium ionic conductivity.

Example 1

[0092] (1) Preparation of Sulfide-Based Inorganic Solid Electrolyte Material 1 for Crystal Nucleating Agent

[0093] A sulfide-based inorganic solid electrolyte material 1 for a crystal nucleating agent was prepared according to the following procedure.

[0094] Regarding the raw materials, Li.sub.2S (manufactured by Furukawa Co., Ltd., purity: 99.9%), P.sub.2S.sub.5 manufactured by Kanto Chemical Co., Inc.), and Li.sub.3N (manufactured by Furukawa Co., Ltd.) were used.

[0095] Next, in an argon glove box, Li.sub.2S powder, P.sub.2S.sub.5 powder, and Li powder were weighed (Li.sub.2S:P.sub.2S:Li.sub.3N=27:9:2 (molar ratio)), and all the powders were mixed in an agate mortar for 10 minutes.

[0096] Next, 1 g of the mixed powder was weighed, was put into a zirconia pot (inner volume: 45 mL) with 18 zirconia balls having a diameter ϕ of 10 mm, and was crushed and mixed using a planetary ball mill (rotation: 800 rpm, revolution: 400 rpm) for 30 hours. As a result, the sulfide-based inorganic solid electrolyte material (Li.sub.10P.sub.3S.sub.12) in the vitreous state was obtained.

[0097] Next, the sulfide-based inorganic solid electrolyte material in the vitreous state was annealed in argon at 290° C. for 2 hours. As a result the sulfide-based inorganic solid electrolyte material (Li.sub.10:P.sub.:3S.sub.12) in the glass ceramic state was obtained. Next, the obtained sulfide-based inorganic solid electrolyte material in the glass ceramic state is crushed and mixed using a planetary ball mill (rotation: 800 rpm, revolution: 400 rpm) for 30 hours and was vitrified again. As a result, the sulfide-based inorganic solid electrolyte material 1 for the crystal nucleating agent was obtained.

[0098] (2) Preparation of Target Sulfide-Based Inorganic Solid Electrolyte Material

[0099] The target sulfide-based inorganic solid electrolyte material was prepared according to the following procedure.

[0100] Regarding the raw materials, Li.sub.2S (manufactured by Furukawa Co., Ltd., purity: 99.9%), P.sub.2S.sub.5 (manufactured by Kanto Chemical Co., Inc.), and Li.sub.3N (manufactured by Furukawa Co., Ltd.) were used.

[0101] Next, in an argon glove box, Li.sub.2S powder, P.sub.2S.sub.5 powder, and Li.sub.3N powder were weighed (Li.sub.2S:P.sub.2S.sub.5:Li.sub.3N=27:9:2 (molar ratio)), the sulfide-based inorganic solid electrolyte material 1 for the crystal nucleating agent was weighed such that the content thereof was as shown in Table 1 with respect to the raw material powders, and all the powders were mixed in an agate mortar for 10 minutes.

[0102] Next, 1 g of the mixed powder (raw material inorganic composition (A)) was weighed, was put into a zirconia pot (inner volume: 45 mL) with 18 zirconia balls having a diameter ϕ of 10 mm, and was crushed and mixed (mechanochemical process) using a planetary ball mill (rotation: 800 rpm, revolution: 400 rpm) for 3 hours. As a result, the sulfide-based inorganic solid electrolyte material (Li.sub.10P.sub.3S.sub.12) in the vitreous state was obtained.

[0103] Next, the sulfide-based inorganic solid electrolyte material in the vitreous state was annealed in argon at 290° C. for 2 hours. As a result, the sulfide-based inorganic solid electrolyte material (Li.sub.10P.sub.3S.sub.12) in the glass ceramic state was obtained.

[0104] The lithium ionic conductivity of each of the obtained sulfide-based inorganic solid electrolyte materials in the vitreous state and the obtained sulfide-based inorganic solid electrolyte materials in the class ceramic state was measured. The obtained results are shown in Table 1.

Examples 2 to 4 and Comparative Example 1

[0105] Sulfide-based inorganic solid electrolyte materials in the vitreous state and sulfide-based inorganic solid electrolyte materials (Li.sub.10P.sub.3S.sub.12) in the glass ceramic state were prepared using the same method as that of Example 1, except that the content of the sulfide-based inorganic solid electrolyte material 1 for the crystal nucleating agent was changed as shown in Table 1. The lithium ionic conductivity of each of the obtained sulfide-based inorganic solid electrolyte materials in the vitreous state and the obtained sulfide-based inorganic solid electrolyte materials in the glass ceramic state was measured. The obtained results are shown in Table 1.

Examples 5 to 9

[0106] Sulfide-based inorganic solid electrolyte materials in the vitreous state and sulfide-based inorganic solid electrolyte materials (Li.sub.10P.sub.3S.sub.12) in the glass ceramic state were prepared using the same method as that of Example 2, except that the time of the mechanochemical process by the planetary ball mill was changed as shown in Table 1. The lithium ionic conductivity of each of the obtained sulfide-based inorganic solid electrolyte materials in the vitreous state and the obtained sulfide-based inorganic solid electrolyte materials in the glass ceramic state was measured. The obtained results are shown in Table 1.

Examples 10 and 11 and Comparative Examples 2 and 3

[0107] (1) Preparation of Sulfide-Based inorganic Solid Electrolyte Material 2 for Crystal Nucleating Agent

[0108] A sulfide-based inorganic solid electrolyte material 2 for a crystal nucleating agent was prepared using the same method as that of the sulfide-based inorganic solid electrolyte material 1 for the crystal nucleating agent, except that the mixing ratio between the respective raw materials was adjusted such that the composition was Li.sub.3PS.sub.4.

[0109] (2) Preparation of Target Sulfide-Based Inorganic Solid Electrolyte Material

[0110] Sulfide-based inorganic solid electrolyte materials in the vitreous state and sulfide-based inorganic solid electrolyte materials (Li.sub.3PS.sub.4) in the glass ceramic state were prepared using the same method as that of Example 1, except that the mixing ratio between the respective raw materials was adjusted such that the composition was Li.sub.3PS.sub.4, time of the mechanochemical process by the planetary ball mill was changed as shown in Table 1, and the kind and the content of the sulfide-based inorganic solid electrolyte material for the crystal nucleating agent were changed as shown in Table 1. The lithium ionic conductivity of each of the obtained sulfide-based inorganic solid electrolyte materials in he vitreous state and the obtained sulfide-based inorganic solid electrolyte materials in the glass ceramic state was measured. The obtained results are shown in Table 1.

TABLE-US-00001 TABLE 1 Kind Lithium Ionic Crystal Nucleating Agent Time of of Solid Conductivity [S .Math. cm.sup.−1] Content Mechanochemical Electrolyte Vitreous Glass Ceramic Kind [mass %] Process (h) Material State State Example 1 Li.sub.10P.sub.3S.sub.12 40 3 h (3 h × 1) Li.sub.10P.sub.3S.sub.12 1.44 × 10.sup.−4 1.35 × 10.sup.−3 Example 2 Li.sub.10P.sub.3S.sub.12 30 3 h (3 h × 1) Li.sub.10P.sub.3S.sub.12 1.47 × 10.sup.−4 1.36 × 10.sup.−3 Example 3 Li.sub.10P.sub.3S.sub.12 20 3 h (3 h × 1) Li.sub.10P.sub.3S.sub.12 1.35 × 10.sup.−4 1.08 × 10.sup.−3 Example 4 Li.sub.10P.sub.3S.sub.12 10 3 h (3 h × 1) Li.sub.10P.sub.3S.sub.12 1.28 × 10.sup.−4 0.64 × 10.sup.−3 Example 5 Li.sub.10P.sub.3S.sub.12 30 3 h (1.5 h × 2) Li.sub.10P.sub.3S.sub.12 1.51 × 10.sup.−4 1.43 × 10.sup.−3 Compartive Li.sub.10P.sub.3S.sub.12 0 3 h (3 h × 1) Li.sub.10P.sub.3S.sub.12 1.20 × 10.sup.−4 0.53 × 10.sup.−3 Example 1 Example 6 Li.sub.10P.sub.3S.sub.12 30 6 h (3 h × 2) Li.sub.10P.sub.3S.sub.12 2.67 × 10.sup.−4 1.77 × 10.sup.−3 Example 7 Li.sub.10P.sub.3S.sub.12 30 12 h (6 h × 2) Li.sub.10P.sub.3S.sub.12 4.48 × 10.sup.−4 1.91 × 10.sup.−3 Example 8 Li.sub.10P.sub.3S.sub.12 30 16 h (8 h × 2) Li.sub.10P.sub.3S.sub.12 4.59 × 10.sup.−4 1.90 × 10.sup.−3 Example 9 Li.sub.10P.sub.3S.sub.12 30 30 h (15 h × 2) Li.sub.10P.sub.3S.sub.12 4.50 × 10.sup.−4 1.40 × 10.sup.−3 Example 10 Li.sub.3PS.sub.4 30 30 h (15 h × 2) Li.sub.3PS.sub.4 3.61 × 10.sup.−4 0.97 × 10.sup.−3 Compartive Li.sub.3PS.sub.4 0 30 h (15 h × 2) Li.sub.3PS.sub.4 3.62 × 10.sup.−4 0.12 × 10.sup.−3 Example 2 Example 11 Li.sub.3PS.sub.4 30 6 h (3 h × 2) Li.sub.3PS.sub.4 3.24 × 10.sup.−4 0.96 × 10.sup.−3 Compartive Li.sub.3PS.sub.4 0 6 h (3 h × 2) Li.sub.3PS.sub.4 1.70 × 10.sup.−4 0.57 × 10.sup.−3 Example 3

[0111] When the sulfide-based inorganic solid electrolyte materials are classified in terms of the kinds and are compared to each other in the time of the mechanochemical process, it can be understood that, with the method of manufacturing the sulfide-based inorganic solid electrolyte material according to Examples, the sulfide-based inorganic solid electrolyte material having a high ionic conductivity can be obtained within a short period of time.

[0112] Based on the above result, it can be understood that, with the method of manufacturing the sulfide-based inorganic solid electrolyte material according to the present embodiment, the inorganic composition can be vitrified within a shorter period of time, and the manufacturing time can be reduced.

[0113] The present application claims priority based on Japanese Patent Application No. 2019-066565 filed on Mar. 29, 2019, the entire content of which is incorporated herein by reference.