The present invention provides a non-aqueous electrolyte-based high power
lithium secondary battery having a long-term service life and superior
safety at both room temperature and high temperature, even after repeated
high-current charging and discharging, wherein the battery comprises a
mixture of a particular lithium manganese-metal composite oxide (A)
having a spinel structure and a particular lithium
nickel-manganese-cobalt composite oxide (B) having a layered structure,
as a cathode active material.