| 摘要 |
The present invention provides an active material for a lithium secondary battery with a high discharge capacity, particularly for a lithium secondary battery that can increase the discharge capacity in a potential region of 4.3 V or lower, a method for producing the same, a lithium secondary battery having a high discharge capacity, and a method for producing the same. The active material for a lithium secondary battery includes a solid solution of a lithium transition metal composite oxide having anα-NaFeO2 type crystal structure, in which the composition ratio of Li, Co, Ni, and Mn contained in the solid solution satisfies Li1+(1/3)xCo1−x−yNi(1/2)yMn(2/3)x+(1/2)y (x+y≰1, 0≰y and 1−x−y=z); in an Li[Li1/3Mn2/3]O2(x)-LiNi1/2Mn1/2O2(y)-LiCoO2(z) type ternary phase diagram, (x, y, z) is represented by values in a range present on or within a line of a heptagon (ABCDEFG) defined by the vertexes; point A(0.45, 0.55, 0), point B(0.63, 0.37, 0), point C(0.7, 0.25, 0.05), point D(0.67, 0.18, 0.15), point E(0.75, 0, 0.25), point F(0.55, 0, 0.45), and point G(0.45, 0.2, 0.35); and the intensity ratio between the diffraction peaks on (003) plane and (104) plane measured by X-ray diffractometry before charge-discharge is I(003)/I(104)≧1.56 and at the end of discharge is I(003)/I(104)>1. The invention provides a method for producing the active material for a lithium secondary battery using a coprecipitation method, a lithium secondary battery including a positive electrode containing the active material and a method for producing the lithium secondary battery.
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