POSITIVE ELECTRODE ACTIVE MATERIAL FOR ALL-SOLID-STATE LITHIUM ION SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE SAME

A positive electrode active material for an all-solid-state lithium ion secondary battery includes a lithium-nickel composite oxide particle and a coating layer coating a surface of the particle. The lithium-nickel composite oxide particle has a crystal structure belonging to a space group R-3m, contains at least Li, Ni, an element M, and Nb, a molar ratio among the elements being represented by Li:Ni:M:Nb=a:(1-x-y):x:y (0.98≤a≤1.15, 0