Cathode active material and lithium secondary battery for controlling impurity or swelling including the same and method of preparing cathode active material with enhanced productivity

摘要

Disclosed are a cathode active material represented by Formula 1 below and including a metal cation having a greater ionic radius than a Ni cation and represented by M of Formula 1 at a Li cation site or in an empty space within a crystal lattice so as to prevent mixing of Ni cations into a Li layer, a lithium secondary battery including the same, and a method of preparing the cathode active material which has improved productivity.Li_aNi_xMn_yCo_zM_wO_2−tA_t  (1)wherein a, x, y, w, M, A, z, and t are the same as defined in the specification.