HIGH-CAPACITY POSITIVE ELECTRODE ACTIVE MATERIAL WITH IMPROVED CONDUCTIVITY AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY COMPRISING SAME

Disclosed is a cathode active material including a lithium manganese-based oxide. The lithium manganese-based oxide has a spinel structure, exhibits core-shell phase transition by which phase transition of a crystal structure occurs from a cubic structure to a tetragonal structure in a direction from the surface of particles to the center of the particles during discharging to the 3V region, and includes a conductive material at the shell to improve electrical conductivity of the tetragonal structure.