Cathode active material, cathode and lithium battery including cathode active material, and method of preparing the cathode active material

A cathode active material including: a lithium manganese oxide of which primary particles has a diameter of 1µm or more and which has a spinel structure in which an X-ray diffraction (XRD) peak intensity ratio of I(111)/I(311) is 1.0 or more; and a boron element disposed at least one position selected from the group consisting of inside the primary particles and on surfaces of the primary particles.