SECONDARY BATTERY

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material particle. The positive electrode active material particle includes a layered rock-salt lithium composite oxide and a spinel metal oxide. The positive electrode active material particle has therein the spinel metal oxide provided on at least a surface of a particle including the layered rock-salt lithium composite oxide. The electrolytic solution includes a chain carboxylic acid ester and a cyclic ether.