| abstract |
[Problem] To provide a "lithium-excess" active material having high initial efficiency. [Solution] The present invention provides a positive electrode active material for a non-aqueous electrolyte secondary battery, the positive electrode active material containing a lithium-transition metal composite oxide, wherein the lithium-transition metal composite oxide has a structure of α-NaFeO2, has a molar ratio of Li to transition metal (Me), i.e., Li/Me, of less than 1, contains Ni and Mn as the transition metal (Me), has an X-ray diffraction pattern that can be attributed to space group R3-m, and has a (101) plane half-width of 0.22˚ or less in the Miller index hkl as measured by X-ray diffraction using CuKα radiation. |