SULFIDE SOLID ELECTROLYTE AND BATTERY

Provided is a novel sulfide solid electrolyte containing Li, P, S, and a halogen, which can be used as a solid electrolyte for a lithium secondary battery or the like, and is able to suppress the generation of a hydrogen sulfide gas even when exposed to moisture in the atmosphere.The sulfide solid electrolyte comprises a crystal phase or a compound having an argyrodite -type structure and containing Li, P, S, and a halogen; and a compound composed of Li, Cl, and Br and having a peak at each position of 2θ = 29.1° ± 0.5° and 33.7° ± 0.5° in an X-ray diffraction pattern.