SULFIDE SOLID ELECTROLYTE

A sulfide solid electrolyte has peak A at 2θ = 20.7° ± 0.5° in an X-ray diffraction pattern obtained by performing X-ray diffraction measurement using CuKal radiation. It is preferable that the sulfide solid electrolyte has peak B at 2θ = 25.4° ± 1.0° in the X-ray diffraction pattern obtained by performing X-ray diffraction measurement using CuKal radiation. It is also preferable that the value of the ratio of IA to IB, IA/IB, is more than 0 and 0.7 or less, where IA is the intensity of peak A and IB is the intensity of peak B. It is also preferable that the sulfide solid electrolyte has peak C at 2θ = 22.0° ± 0.5° in the X-ray diffraction pattern obtained by performing X-ray diffraction measurement using CuKal radiation.