POSITIVE-ELECTRODE ACTIVE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, AND LITHIUM ION SECONDARY BATTERY

摘要

Provided are a positive-electrode active material capable of exerting a high potential and capable of suppressing the elution of metal elements, and a lithium ion secondary battery having excellent capacity and high-temperature service life. The present invention has: a composite oxide containing Li (lithium) and a transition metal including at least Mn (manganese); and a surface oxide that is an oxide having a metal element with a valence of two or more. The composite oxide is fluorinated in a surface layer section (B) thereof, and is not fluorinated in a center section (C) thereof. The surface oxide (A) is present on the surface of the composite oxide, and is fluorinated.