Metal element-containing sulfide-type solid electrolyte and method for producing same

A method for producing a metal element-containing sulfide solid electrolyte, the method comprising contacting a sulfide solid electrolyte comprising a lithium element, a sulfur element and a phosphorus element, or two or more starting materials comprising a lithium element, a sulfur element and a phosphorus element, with a metal compound,

• wherein a molar ratio of the lithium element to the phosphorus element (Li/P) comprised in the metal element-containing sulfide solid electrolyte is 2.4 or more and 12 or less, and a molar ratio of the sulfur element to the phosphorus element (S/P) is 3.7 or more and 12 or less, and
• the metal compound comprises at least one metal element selected from metal elements of Groups 2 to 12 and Period 4 or higher of the Periodic Table.