Positive electrode active material containing lithium composite oxide and covering material and battery

A positive electrode active material comprising:

• a lithium composite oxide;
• and
• a covering material that covers a surface of the lithium composite oxide,
• wherein the covering material has an electron conductivity of 106 S/m or less,
• the lithium composite oxide is a multiphase mixture, in which a plurality of first regions constituted by a first phase and a plurality of second regions constituted by a second phase are three-dimensionally mixed in a random manner, the first phase having a first crystal structure that belongs to a space group Fm-3m, the second phase having a second crystal structure that belongs to a space group other than a space group Fm-3m, and
• a ratio I(18°-20°)/I(43°-46°) of a first integrated intensity I(18°-20°) of a first maximum peak present at a first diffraction angle 2θ of 18° or more and 20° or less to a second integrated intensity I(43°-46°) of a second maximum peak present at a second diffraction angle 2θ of 43° or more and 46° or less in an XRD pattern of the lithium composite oxide satisfies 0.05≤I(18°-20°)/I(43°-46°)≤0.90.