POSITIVE-ELECTRODE ACTIVE MATERIAL CONTAINING LITHIUM COMPOSITE OXIDE, AND BATTERY INCLUDING THE SAME

A positive-electrode active material contains a lithium composite oxide, wherein the lithium composite oxide is a multiphase mixture including a first phase, of which a crystal structure belongs to a space group Fm-3m, and a second phase, of which a crystal structure belongs to a space group Fd-3m; and in an XRD pattern of the lithium composite oxide, the integrated intensity ratio I/Iof a first maximum peak Iwithin a first range of 18 degrees to 20 degrees at a diffraction angle 2θ to a second maximum peak Iwithin a second range of 43 degrees to 46 degrees at the diffraction angle 2θ satisfies 0.05≤I/I≤0.90.