POSITIVE ELECTRODE ACTIVE MATERIAL AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium positive electrode active material and a nonaqueous electrolyte secondary battery wherein superior cycle characteristics and high temperature storage characteristics can be obtained while suppressing lowering in discharge capacity.

SOLUTION: The nonaqueous electrolyte secondary battery is equipped with a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes: lithium; the main transition metal M1; and particles of lithium transition metal complex oxide to contain a metal element M2 different from the main transition metal M1. The metal element M2 has a concentration gradient from the particle center toward a particle surface. A ratio d(%) from the particle surface to a prescribed depth (=[(mass of main transition metal M1)+(mass of metal element M2)]/(particle all mass)) is a mol fraction r (=(material amount of metal element M2)/[(material amount of main transition metal M1)+(material amount of metal element M2)]) is within a range of 0.20≤r≤0.80 within a range to satisfy 0.020%≤d≤0.050%.

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