METHOD FOR PRODUCING SULFIDE SOLID ELECTROLYTE

1 . A method for producing a sulfide solid electrolyte, the method comprising:

a step of mixing a lithium (Li) element source, a phosphorus (P) element source, and a sulfur (S) element source, thereby obtaining a raw material composition;

a step of firing the raw material composition, thereby obtaining a sulfide;

a step of milling a slurry containing a solvent having fluorine atoms and the sulfide; and

a step of drying the slurry.

2 . The method according to claim 1 , wherein the sulfide in the slurry has a concentration of 3 to 40 mass %.

3 . The method according to claim 1 , wherein the solvent is an organic compound.

4 . The method according to claim 3 , wherein the organic compound has at least one selected from the group consisting of an alkyl group, a vinyl group, an aryl group, an ether group, an ester group, a hydroxy group, an aldehyde group, a carbonyl group, a carboxy group, an amino group, and a sulfo group.

5 . The method according to claim 1 , wherein the step of milling is performed in an environment with a temperature which is −20° C. or lower than a dew point.

6 . The production method according to claim 1 , wherein the step of milling is a step of dry milling the sulfide, and mixing the dry milled sulfide and the solvent, thereby preparing the slurry.

7 . The method according to claim 1 , wherein the sulfide has a crystalline phase with an argyrodite-type crystal structure.