| abstract |
The present invention provides a positive electrode active material with which an increase in the interface resistance between the positive electrode active material and a sulfide solid electrolyte over time can be suppressed and also the interface resistance is low. The positive electrode active material of the present invention includes particles that have core particles containing a complex oxide of lithium and a metal element and a coating layer arranged on the surface of the core particles, and is used in a solid-state battery containing a sulfide solid electrolyte. The coating layer is composed of an oxide containing Li and M, where M represents one or two or more elements selected from the group consisting of B, Nb, Ti, Zr, Ta, Zn, W, and Al, or M is B when M represents one element. The molar ratio of Li/M on the surface of the coating layer, as obtained by X-ray photoelectron spectroscopy, is from 0.85 to 3.95. |