Cathode active material and lithium secondary battery containing them
View Patent ↗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 mixture of a lithium/manganese spinel oxide having a substitution of a manganese (Mn) site with a certain metal ion and a lithium/nickel/cobalt/manganese composite oxide, as a cathode active material.
1. A cathode active material for a lithium secondary battery, comprising a mixture of a lithium/manganese cathode oxide represented by Formula I and a lithium/nickel/cobalt/manganese oxide represented by Formula II:
Li 1+x Mn 2−y M y O 4 (I)
Li 1+z Ni 0.4 Mn 0.4 CO 0.2 O 2 (II)
wherein,
M is a metal having an oxidation number of 2 to 3;
0≦x≦0.2;
0<y≦0.2;
0≦z≦0.1;
Wherein, the mixture of the lithium/manganese spinel oxide of Formula I and the lithium/nickel/cobalt/manganese composite oxide of Formula II is in the ratio of 30:70 to 70:30 by weight.
2. The cathode active material according to claim 1 , wherein M in Formula I is aluminum (Al), magnesium (Mg) or both of them.
3. The cathode active material according to claim 1 , wherein the value of y is in the range of 0.01 to 0.2.
4. A lithium secondary battery comprising the cathode active material of claim 1 .
5. A lithium secondary battery comprising the cathode active material of claim 2 .
6. A lithium secondary battery comprising the cathode active material of claim 3 .
7. A lithium secondary battery comprising the cathode active material of claim 1 .