Abstract: The present invention relates to a sulfide solid electrolyte to be used for a lithium-ion secondary battery, the sulfide solid electrolyte including: an argyrodite crystal including Li, P, S, and Ha, in which the Ha represents at least one element selected from the group consisting of F, Cl, Br, and I, and the Ha includes at least one of Cl and Br, the argyrodite crystal satisfies at least one of requirements (A) and (B), and in the argyrodite crystal, relationships of {(1/?(S))×[S2?]+(1/?(O))×[O2?]+(1/?(Br))×[Br?]+(1/?(Cl))×[Cl?]+(1/?(F))×[F?]}?0.36 and [S2?]+[O2?]+[Br?]+[Cl?]+[F?]=1 are satisfied.

Abstract: The present invention relates to a sulfide solid electrolyte to be used for a lithium-ion secondary battery. The sulfide solid electrolyte contains: an argyrodite crystal containing Li, P, S, and Ha (F, Cl, Br, and I). Relationships of {(1/?(S))×[S2-]0+(1/?(O))×[O2-]0+(1/?(Br))×[Br?]0+(1/?(Cl))×[Cl?]0+(1/?(F))×[F?]0}?0.33 and [S2-]0+[O2-]0+[Br?]0+[Cl?]0+[F?]0=1 are satisfied, where [S2-]0, [O2-]0, [Br?]0, [Cl?]0, and [F?]0 are surface anion contents, and ? is an electronegativity thereof.