| abstract |
A positive active material for lithium secondarynbatteries is provided with which a lithium secondarynbattery having a high energy density and excellentncharge/discharge cycle performance can be obtained. Alsonprovided is a lithium secondary battery having a highnenergy density and excellent charge/discharge cyclenperformance. n The positive active material for lithium secondarynbatteries is characterized by comprising a composite oxidenwhich is represented by the composite formula Li x Mn a Ni b Co c O 2 n(wherein a, b, and c are values within such a range that inna ternary phase diagram showing the relationship amongnthese, (a, b, c) is present on the perimeter of or insidenthe quadrilateral ABCD defined by point A (0.5, 0.5, 0),npoint B (0.55, 0.45, 0), point C (0.55, 0.15, 0.30), andnpoint D (0.15, 0.15, 0.7) as vertexes, andn0.95<x/(a+b+c)<1.35) and has an α-NaFeO 2 structure. Thenlithium secondary battery employs this active material. |