| abstract |
PROBLEM TO BE SOLVED: To provide a positive electrode active material particle powder having a high capacity and a high capacity retention rate and excellent in a high temperature overcharge test, a production method thereof, and a secondary battery using the same. SOLUTION: Positive electrode active material particles having core particles made of lithium cobaltate having a layered structure containing element M (M is Mg and / or Al), and a surface layer made of lithium cobaltate having a layered structure in which at least Ti is dissolved. A positive electrode active material particle powder, wherein the average layer thickness of the surface layer is 0.005 to 1.5 μm, and the BET specific surface area is 0.02 to 0.25 m 2 / g. [Selection figure] None |