Positive electrode active material and lithium secondary battery including the same
Disclosed herein are a positive electrode active material including at least one selected from among compounds represented by Formula 1 below and a lithium secondary battery including the same that is capable of improving lifetime characteristics and rate characteristics while exhibiting excellent safety: Li[Li x M y M′ (1-x-y) ]O 2-z A z (1), where M is at least one element selected from a group consisting of Ru, Mo, Nb, Te, Re, Ir, Pt, Cr, S, W, Os, and Po, M′ is at least one element selected from a group consisting of Ni, Ti, Co, Al, Mn, Fe, Mg, B, Cr, Zr, Zn, and second row transition metals, A is a negative monovalent or divalent anion, and 0<x<0.3, 0.2≤y≤0.5, 0≤z<0.5, and 0.2<x+y<0.8.
1. A positive electrode active material comprising at least one selected from among compounds represented by Formula 1 below:
Li[Li x M y M′ (1-x-y) ]O 2-z A z (1),
where
M is at least one element selected from a group consisting of Ru, Te, Re, Ir, Pt, S, W, Os, and Po,
M′ is at least one element selected from a group consisting of Ni, Ti, Co, Al, Mn, Fe, Mg, B, Cr, Zr, Zn, and second row transition metals,
A is a negative monovalent or divalent anion, and
0<x<0.3, 0.2≤y≤0.5, 0≤z<0.5, and 0.2<x+y<0.8.
2. The positive electrode active material according to claim 1 , wherein M is at least one element selected from a group consisting of Ru, S, W, Os, and Po.
3. The positive electrode active material according to claim 2 , wherein M is Ru.
4. The positive electrode active material according to claim 1 , wherein M′ is at least two elements selected from a group consisting of Ni, Ti, Co, Al, Fe, Mg, B, Cr, Zr, and Zn.
5. The positive electrode active material according to claim 1 , wherein M′ (1-x-y) is Ni a Mn b (0<a<0.8, 0<b<0.8, and a+b+x+y=1).
6. The positive electrode active material according to claim 5 , wherein 0.1≤a≤0.6, 0<b<0.8, 0.5≤a+b≤0.8, and a+b+x+y=1.
7. The positive electrode active material according to claim 1 , wherein 0<x≤0.25.
8. The positive electrode active material according to claim 1 , wherein 0.2≤y≤0.4.
9. The positive electrode active material according to claim 1 , wherein 0.2<x+y≤0.6.
10. The positive electrode active material according to claim 1 , wherein A is at least one element selected from a group consisting of halogen elements, sulfur, and nitrogen.
11. A positive electrode for secondary batteries formed by applying a positive electrode active material according to claim 1 to a current collector.
12. A lithium secondary battery comprising a positive electrode for secondary batteries according to claim 11 .
13. A battery module comprising a lithium secondary battery according to claim 12 as a unit battery.
14. A battery pack comprising a battery module according to claim 13 .
15. A device using a battery pack according to claim 14 as a power source.
16. The device according to claim 15 , wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage apparatus.
17. The positive electrode material of claim 1 , wherein 0<z<0.5, and A is at least one selected from the group consisting of F, Cl, Br, I, S, and N.