LITHIUM SECONDARY BATTERY ACTIVE MATERIAL, LITHIUM SECONDARY BATTERY ELECTRODE AND LITHIUM SECONDARY BATTERY

It is an object of the present invention to provide an active material for a lithium secondary battery having high discharge capacity and excellent in high rate discharge characteristics and a lithium secondary battery using the same. The active material for a lithium secondary battery containing a solid solution of a lithium-transition metal composite oxide having an ±-NaFeO 2 type crystal structure and the lithium secondary battery using the same have features that the composition ratios of the metal elements contained in the solid solution satisfy Li 1 +( x/3 )Co 1-x-y-z Ni y/2 Mg z/2 Mn (2x/3)+(y/2)+(z/2) (x > 0; y > 0; z > 0; x + y + z < 1); the active material has an X-ray diffraction pattern capable of belonging to space group P3 1 12; and the active material has discharge capacity exceeding 200 mAh/g. Further, in addition to the above-mentioned features, they have features that an intensity ratio between the diffraction peak of (003) plane and the diffraction peak of (114) plane measured by X-ray diffractometry is I (003) /I (114) ‰¥ 1.15 and/or the half width of the diffraction peak of (003) plane is 0.15° or less and the half width of the diffraction peak of (114) plane is 0.25° or less.