POSITIVE ELECTRODE ACTIVE MATERIAL AND BATTERY INCLUDING THE SAME

A positive electrode active material includes a lithium composite oxide having a crystal structure belonging to the space group Fd-3m and has an integrated intensity ratio I/Iof greater than or equal to 0.05 and less than or equal to 0.90 and an integrated intensity ratio I/Iof greater than or equal to 0.8 and less than or equal to 2.0. The integrated intensity ratio I/Iis a ratio of an integrated intensity Ito an integrated intensity I. The integrated intensity ratio I/Iis a ratio of an integrated intensity Ito an integrated intensity I. The integrated intensity Iis an integrated intensity of a maximum peak present in a range of angle of diffraction 2θ greater than or equal to A° and less than or equal to B° in the X-ray diffraction pattern of the positive electrode active material.