Positive electrode active material for all-solid-state lithium-ion secondary batteries, and all-solid-state lithium-ion secondary batteries

Abstract

To provide a positive electrode active material with high discharge capacity for use as a positive electrode active material in all-solid-state secondary batteries. [Solution] A positive electrode active material for an all-solid-state lithium-ion secondary battery, comprising lithium transition metal composite oxide particles, a first coating layer disposed in contact with the surface of the lithium transition metal composite oxide particles, and a second coating layer disposed on the first coating layer, wherein the first coating layer contains an oxide-based solid electrolyte having lithium ion conductivity, and the second coating layer contains a material that can suppress reaction with a sulfide-based solid electrolyte.