| abstract |
Provided is a lithium secondary battery active material having a large discharge capacity and excellent in high-rate discharge characteristics, and also provided is a lithium secondary battery using the lithium secondary battery active material.nThe lithium secondary battery active material including a solid solution of a lithium transition metal composite oxide having an α-NaFeO 2 -type crystal structure and the lithium secondary battery using the lithium secondary battery active material are characterized in: having the composite ratio of the metal elements included in the solid solution, which satisfies Li 1+(x/3) Co 1-x-y-z Ni y/2 Mg z/2 Mn (2x/3)+(y/2)+(z/2) , where x>0, y>0, z>0, and x+y+z<1; having an X-ray diffraction pattern that can belong to the space group P3 1 12; and having a discharge capacity exceeding 200 mAh/g. In addition to the above characteristics, the lithium secondary battery active material and the lithium secondary battery are characterized in that the intensity ratio of the diffraction peaks in the (003) and (114) planes obtained by X-ray diffraction measurements is I (003) /I (114) ≥ 1.15 and/or the half-value width of the diffraction peak in the (003) plane is 0.15° or less and the half-value width of the diffraction peak in the (114) plane is 0.25° or less. |