| 摘要 |
[Object] There is provided an active material for a lithium secondary battery, which has a high initial efficiency and a high discharge capacity, and particularly has a high discharge capacity at a low temperature (excellent low-temperature characteristic), and a lithium secondary battery using the active material. [Solution] An active material for a lithium secondary battery, which contains a solid solution of a lithium transition metal composite oxide having an ±-NaFeO 2 crystal structure, wherein the composition ratio of metal elements contained in the solid solution satisfies, Li 1+x-y Na y Co a Ni b Mn c O 2+d (0 < y ‰¤ 0.1, 0.4 ‰¤ c ‰¤ 0.7, x+a+b+c=1,0.1‰¤x‰¤ 0.25, -0.2 ‰¤ d ‰¤ 0.2), the active material has an X-ray diffraction pattern attributable to a space group R3-m (P3 1 12), and in the Miller index hkl, the half width of the diffraction peak of the (003) is 0.30° or less and the half width of the diffraction peak of the (114) plane is 0.50° or less. Further, the average of three oxygen position parameters determined from crystal structure analysis by the Rietveld method on the basis of the X-ray diffraction pattern is preferably 0.264 or less. |
