Active material for a lithium secondary battery, method of manufacturing the same, electrode including the active material, and lithium secondary battery including the electrode
An active material for a lithium secondary battery, a method of manufacturing the same, an electrode including the active material, and a lithium secondary battery including the electrode, the active material including a lithium composite oxide represented by the following Formula 1: Li[Li x Ni a Co b Mn c ]O 2-y F y . [Formula 1]
1. An active material for a lithium secondary battery, the active material comprising a lithium composite oxide represented by the following Formula 1:
Li[Li x Ni a Co b Mn c ]O 2-y F y , [Formula 1]
wherein:
in Formula 1, x, a, b, c, and y satisfy the following relations: 0.05≦x≦0.3, 0.12≦a≦0.25, 0.00≦b≦0.25, 0.45≦c≦0.60, x+a+b+c=1.0, 1.25≦(1+x)/(a+b+c)≦1.6, and 0<y≦0.1, and
the lithium composite oxide has a full width at half maximum of a diffraction angle at a (003) surface of about 0.216° to about 0.219° in a powder X-ray diffraction spectrum obtained by using CuKα ray.
2. The active material as claimed in claim 1 , wherein the lithium composite oxide represented by Formula 1 is represented by the following Formula 1a:
Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-y F y , in which 0<y≦0.1. [Formula 1a]
3. The active material as claimed in claim 1 , wherein, in Formula 1, 0.02≦y≦0.06.
4. The active material as claimed in claim 1 , wherein the lithium composite oxide represented by Formula 1 is one of Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.96 F 0.04 , Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.94 F 0.06 , or Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.98 F 0.02 .
5. The active material as claimed in claim 1 , wherein, in Formula 1, x, a, b, c, and y satisfy the following relations: 0.1≦x≦0.2, 0.17≦a≦0.21, 0.05≦b≦0.17, 0.50≦c≦0.55, 0.01≦y≦0.1.
6. A method of manufacturing an active material for a lithium secondary battery, the method comprising:
mixing a fluorine-containing compound, a lithium compound, and a metal hydroxide represented by the following Formula 2:
Ni a Co b Mn c (OH) 2 [Formula 2]
wherein, in Formula 2, a, b, and c satisfy the following relations: 0.15≦a≦0.30, 0.0≦b≦0.30, 0.55≦c≦0.70, and a+b+c=1.0;
heat treating the mixture under an oxidizing atmosphere at a temperature of about 650° C. to about 850° C.; and
cooling the heat treated mixture at a cooling rate of about 0.1° C./min to about 2° C./min such that the active material includes a lithium composite oxide having a full width at half maximum of a diffraction angle at a (003) surface of about 0.216° to about 0.219° in a powder X-ray diffraction spectrum obtained by using CuKα ray.
7. The method as claimed in claim 6 , wherein the lithium composite oxide is represented by the following Formula 1:
Li[Li x Ni a Co b Mn c ]O 2-y F y , [Formula 1]
wherein, in Formula 1, x, a, b, c, and y satisfy the following relations: 0.05≦x≦0.3, 0.12≦a≦0.25, 0.00≦b≦0.25, 0.45≦c≦0.60, x+a+b+c=1.0, 1.25≦(1+x)/(a+b+c)≦1.6, and 0<y≦0.1.
8. The method as claimed in claim 6 , wherein the fluorine-containing compound includes LiF or NH 4 F.
9. The method as claimed in claim 6 , wherein the cooling is performed for about 350 to about 7,000 minutes.
10. The method as claimed in claim 6 , wherein the heat treating is performed at about 675° C. to about 750° C.
11. The method as claimed in claim 6 , wherein the heat treating is performed for about 1 to about 10 hours.
12. The method as claimed in claim 6 , wherein the oxidizing atmosphere includes:
about 10 to about 20 vol % of oxygen or air, and
about 80 to about 90 vol % of inert gas.
13. The method as claimed in claim 6 , wherein the metal hydroxide represented by Formula 2 includes one of Ni 1/6 Co 1/6 Mn 1/2 (OH) 2 or Ni 0.2 Co 0.2 Mn 0.6 (OH) 2 .
14. The method as claimed in claim 7 , wherein the active material represented by Formula 1 is one of Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.96 F 0.04 , Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.94 F 0.06 , or Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 1.98 F 0.02 .
15. An electrode for a lithium secondary battery, the electrode comprising the active material as claimed in claim 1 .
16. A lithium secondary battery including the electrode as claimed in claim 15 .
17. The active material as claimed in claim 1 , wherein the lithium composite oxide is prepared by:
mixing a fluorine-containing compound, a lithium compound, and a metal hydroxide represented by the following Formula 2:
Ni a Co b Mn c (OH) 2 [Formula 2]
wherein, in Formula 2, a, b, and c satisfy the following relations: 0.15≦a≦0.30, 0.0≦b≦0.30, 0.55≦c≦0.70, and a+b+c=1.0;
heat treating the mixture under an oxidizing atmosphere at a temperature of about 650° C. to about 850° C.; and
cooling the heat treated mixture at a cooling rate of about 0.1° C./min to about 2° C./min.