Cathode active material for lithium secondary battery
Disclosed is a cathode active material for secondary batteries, comprising at least one compound selected from the following Formula 1: xLi 2 MO 3 *yLiM′O 2 *zLi 3 PO 4 (1) wherein M is at least one element selected from 1 period or 2 period metals having an oxidation number of +4; M′ is at least one element selected from 1 period or 2 period metals having a mean oxidation number of +3; and 0.1≦x≦0.9, 0.1≦y≦0.9, 0<z≦0.2 and x+y+z=1.
1. A cathode active material for secondary batteries, comprising at least one compound selected from the following Formula 1:
x Li 2 M 1-a A a O 3-b B b *y LiM′ 1-a′ A′ a′ O 2-b′ B b′ *z Li 3 P 1-a″ A″ a″ O 4-b″ B″ b″ (1)
wherein M is at least one element selected from 1 period or 2 period metals having an oxidation number of +4;
M′ is at least one element selected from 1 period or 2 period metals having a mean oxidation number of +3;
A and A′ are a metal or non-metal element that may have a 6-coordinaion structure, respectively;
A″ is an element stable for a 4-coordination structure;
B, B′, and B″ are another anion, respectively; and
0.1≦x≦0.9, 0.1≦y≦0.9, 0<z≦0.2, x+y+z=1, 0≦a≦0.1, 0≦a′≦0.1, 0≦a″≦0.1, 0≦b≦0.1, 0≦b′≦0.1, 0≦b″≦0.1,
wherein the at least one compound selected from Formula 1 is prepared by applying heat treatment to precursor materials for their conversion into the at least one compound, and the active material of Formula 1 is in the form of a composite or a solid solution.
2. The cathode active material according to claim 1 , wherein, in Formula 1, z satisfies 0<z<0.1.
3. The cathode active material according to claim 1 , wherein M is at least one element selected from the group consisting of Mn, Sn, Ti and Zr.
4. The cathode active material according to claim 3 , wherein M is Mn.
5. The cathode active material according to claim 1 , wherein M′ is at least two elements selected from the group consisting of Mn, Ni and Co.
6. The cathode active material according to claim 5 , wherein M′ comprises Mn and Ni.
7. A cathode mix for secondary batteries comprising the cathode active material according to claim 1 .
8. A cathode for lithium secondary batteries in which the cathode mix according to claim 7 is applied to a current collector.
9. A lithium secondary battery comprising the cathode according to claim 8 .
10. A medium and large battery pack comprising the lithium secondary battery according to claim 9 as a unit battery.