| 摘要 |
A positive active material for lithium secondary batteries is provided with which a lithium secondary battery having a high energy density and excellent charge/discharge cycle performance can be obtained. Also provided is a lithium secondary battery having a high energy density and excellent charge/discharge cycle performance. <??>The positive active material for lithium secondary batteries is characterized by comprising a composite oxide which is represented by the composite formula LixMnaNibCocO2 (wherein a, b, and c are values within such a range that in a ternary phase diagram showing the relationship among these, (a, b, c) is present on the perimeter of or inside the quadrilateral ABCD defined by point A (0.5, 0.5, 0), point B (0.55, 0.45, 0), point C (0.55, 0.15, 0.30), and point D (0.15, 0.15, 0.7) as vertexes, and 0.95<x/(a+b+c)<1.35) and has an alpha -NaFeO2 structure. The lithium secondary battery employs this active material. <IMAGE> |
