For lithium ion batteries sulfide-based solid electrolyte and the solid electrolyte compound

Relates for lithium ion batteries sulfide-based solid electrolyte compound having a cubic Argyrodite type crystal structure, it is possible to suppress the generation amount of hydrogen sulfide in when left to stand in the atmosphere, high conductivity even when left to stand in dry air it is possible to maintain the rate, to St. propose a new compound. Containing a crystal phase of cubic system Argyrodite type crystal structure, composition formula (1): a in