POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM ION SECONDARY BATTERY AND METHOD FOR PRODUCING THE SAME, POSITIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, AND LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a positive electrode active material used for a lithium ion secondary battery excellent in battery characteristics, specifically in cycle characteristics.SOLUTION: In a positive electrode active material for a lithium ion secondary battery, a metal oxide in which a part of O is replaced with a halogen element is supported on at least a part of a surface of a lithium-containing composite oxide which contains Li and at least one or more transition metal elements selected from among Ni, Co and Mn and has a Li content of 0.95 times or more in a molar ratio relative to the total amount of the content of the transition metal elements.