| 摘要 |
<p>A positive electrode active material for a lithium secondary cell having a high energy density and excellent in charging/discharging cycle performance, and a lithium secondary cell having a high energy density and excellent in charging/discharging cycle performance are disclosed. A positive electrode active material for a lithium secondary cell is characterized in that the composition of the active material is LixMnaNibCocO2 (where a, b, and c are values of a point (a, b, c) on a side of or inside a quadrilateral ABCD having vertexes A(0.5, 0.5, 0), B(0.55, 0.45, 0), C(0.55, 0.15, 0.30), and D(0.15, 0.15, 0.7)) on a ternary state diagram showing the relationship among a, b, and c, and satisfy the expressions 0.95<x/(a+b+c)<1.35) and in that the active material contains a composite oxide having an α-NaFeO2 structure. The lithium secondary cell comprises this active material.</p> |
