Cathode active material and lithium secondary battery containing the same

摘要

Provided is a non-aqueous electrolyte-based, high-power lithium secondary battery having a long service life and superior safety at both room temperature and high temperature, even after repeated high-current charging and discharging. The battery comprises a cathode active material composed of a mixture of lithium/manganese spinel oxide and lithium/nickel/cobalt/manganese composite oxide wherein the cathode active material exhibits the life characteristics that the capacity at 300 cycles is more than 70% relative to the initial capacity, in the provision of satisfying the condition (i) regarding the particle size and the condition (ii) regarding the mixing ratio.

主权项

1. A cathode active material for a lithium secondary battery, comprising a mixture of a lithium/manganese spinel oxide represented by Formula I and a lithium/nickel/cobalt/manganese composite oxide represented by Formula II, wherein the cathode active material exhibits the life characteristics that the capacity at 300 cycles is more than 80% relative to the initial capacity, in the provision that the below conditions (i) and (ii) are satisfied,
(i) the lithium/manganese spinel oxide of Formula I has an average particle diameter of 15-30 μm, or the lithium/manganese spinel oxide of Formula I and the lithium/nickel/cobalt/manganese composite oxide of Formula II have an average particle diameter of 15-30 μm, respectively; and (ii) the mixing ratio of the lithium/manganese spinel oxide:lithium/nickel/cobalt/manganese composite oxide is in the range of 10:90 to 70:30 (w/w),
Li1+xMn2O4  (I)Li1+yNibMncCo1−(b+c)O2  (II)wherein,
0≦x≦0.2; 0≦y≦0.1; 0.2≦b≦0.7; 0.2≦c≦0.7; and b+c<1; wherein each oxide is an aggregate of large numbers of oxide units, and wherein an oxide unit of the lithium/manganese spinel oxide of Formula I has a particle diameter of 0.2 to 12 μm and surface area of 0.1 to 1.0 m2/g.