Lithium secondary battery

A lithium secondary battery having improved load characteristics such as high rate discharge properties is obtained by using a mixed cathode active material comprising a mixture of lithium-containing manganese oxide having a spinel type crystal structure and lithium-containing cobalt oxide, wherein the cathode collector retains mixed cathode active material in such a manner that the mixing ratio of lithium cobaltate X thereof should fall in a range of 0.1 ≤ X ≤ 0.9, that the bulk density Y (g/cm ) of the cathode mixed agent should be confined in a range satisfying the relation of 0.5X + 2.7 ≤ Y ≤ 0.6X + 3.3, and that the mean particle diameter of spinel type lithium manganate should be greater than the mean particle diameter of lithium cobaltate.