Sulfide solid electrolyte material, battery, and method for producing sulfide solid electrolyte material

A sulfide solid electrolyte material comprising as a main body a crystal structure having an octahedron O comprising an M1 element and an S element, a tetrahedron T1 comprising an M2a element and an S element, and a tetrahedron T2 comprising an M2b element and an S element, in which the tetrahedron T1 and the octahedron O share an edge, and the tetrahedron T2 and the octahedron O share a corner;

• and
• wherein M1 is at least one kind selected from the group consisting of Li, Na, K, Mg, Ca and Zn;
• and
• M2a and M2b are each independently at least one kind selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V and Nb.

A method for producing a sulfide solid electrolyte material, comprising the steps of:

• an ion conductive material synthesizing step of synthesizing a crystalline ion conductive material by using a raw material composition containing an M1 element (M1 is at least one kind selected from the group consisting of Li, Na, K, Mg, Ca and Zn), an M2 element (M2 is at least one kind selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V and Nb), and an S element;
• a crystallinity decreasing step of decreasing crystallinity of the ion conductive material by mechanical milling;
• and
• a heating step of heating the ion conductive material with the crystallinity decreased to obtain a sulfide solid electrolyte material having a peak in positions of 2θ=20.18°±0.50°, 20.44°±0.50°, 26.96°±0.50° and 29.58°±0.50° in an X-ray diffraction measurement using a CuKα line, and having an IB/IA value of 0.25 or less when a diffraction intensity at the peak of 2θ=29.58°±0.50° is represented by IA and a diffraction intensity at a peak of 2θ=27.33°±0.50° is represented by IB.