POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE, SECONDARY BATTERY, ELECTRONIC DEVICE, AND VEHICLE

A positive electrode active material with high charge and discharge capacity is provided. A positive electrode active material with high charge and discharge voltage is provided. A secondary battery which hardly deteriorates is provided. A highly safe power storage device is provided. A novel secondary battery is provided. The positive electrode active material contains cobalt, oxygen, and fluorine and includes a bond of the cobalt and the fluorine in a surface portion or the vicinity of a grain boundary. By having the bond with fluorine, at least part of cobalt is high-spin (paramagnetic) Co. Thus, in ESR analysis, the spin concentration at 113 K is higher than the spin concentration at 300 K by 1.1×10spins/g or more.