Coated positive electrode active material, positive electrode for nonaqueous secondary battery, nonaqueous secondary battery, and their production methods

摘要

Disclosed is a nonaqueous secondary battery (100) comprising a positive electrode (155) having a positive current collector (151) made of a metal, and a positive electrode active material (153) composed of a lithium-metal complex oxide. The surface of the positive electrode active material (153) is coated with a lithium salt (158) having an average thickness of 20-50 nm.

主权项

1. A method of producing a coated positive electrode active material in which a positive electrode active material made of lithium-metal complex oxide has a surface coated with a coating of lithium salt containing lithium carbonate and having an average thickness of 20 to 50 nm, the method comprising:
a first firing step of firing a raw material for the positive electrode active material in a reaction system having an oxygen atmosphere; and a second firing step, following the first firing step, of supplying CO2 gas into the reaction system having the oxygen atmosphere and firing the raw material in the reaction system having the oxygen atmosphere containing CO2 at a higher concentration than in the first firing step, the second firing step including firing the raw material for 4 to 8 hours in an oxygen atmosphere at a CO2 concentration of 300 to 400 ppm to form the coating of lithium salt having an average thickness of 20 to 50 nm on the surface of the positive electrode active material.