| abstract |
An object of the present invention is to provide an active material for a lithium secondary battery having a large discharge capacity and excellent high efficiency discharge characteristics, and a lithium secondary battery using the same. The [MEANS FOR SOLVING PROBLEMS] α-NaFeO a lithium secondary battery using a lithium secondary battery active material and this, containing a solid solution of a lithium transition metal compound oxide having a second crystal structure, the composition ratio of the metal elements contained in the above solid solution, Li 1 + (x / 3) Co 1- xy- z Ni y / 2 Mg z / 2 Mn (2x / 3) + (y / 2) + (z / 2) (x> 0, y> 0, z> 0, It is characterized by having an X-ray diffraction pattern that satisfies x + y + z <1, and is attributed to the space group P3 1 12, and has a discharge capacity exceeding 200 mAh / g. In addition to the above-mentioned features, the intensity ratio of the diffraction peaks of the (003) plane and the (114) plane by X-ray diffraction measurement is I (003) / I (114) ≥ 1.15, and / or (003 The half width of the diffraction peak of the plane) is 0.15 ° or less, and the half width of the diffraction peak of the (114) plane is 0.25 ° or less. |