| abstract |
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. n Li a Ni x Mn y Co z M w O 2-t A t (1)n wherein a, x, y, w, M, A, z, and t are the same as defined in the specification. |