Positive active material for lithium secondary battery and method of preparing same
Disclosed in a positive active material for a lithium secondary battery including a compound represented by formula 1 and having a 10% to 70% ratio of diffracted intensity of diffraction lines in 2θ=53° (104 plane) with respect to diffracted intensity of diffraction lines in the vicinity of 2θ=22° (003 plane) in X-ray diffraction patterns using a CoKα-ray, Li x CoO 2-y A y (1) wherein, x is from 0.90 to 1.04, y is from 0 to 0.5, and A is selected from the group consisting of F, S and P.
1. A method of preparing a positive active material for a lithium secondary battery, comprising:
mixing a lithium source and a cobalt source at a mole ratio of 0.90 to 1.04 of lithium based on 1 mole of cobalt; and
sintering the mixture at 950 to 980° C. for six to ten hours,
producing the positive active material comprising a compound represented by formula 1:
Li x CoO 2-y A y (1)
wherein x is from 0.90 to 1.04, y is from 0 to 0.5, A is selected from the group consisting of F, S, and P, and the positive active material has a ratio of diffracted intensity of diffraction lines in 2θ=53° (104 plane) with respect to diffracted intensity of diffraction lines in the vicinity of 2θ=22° (003 plane) in X-ray diffraction patterns using a CoKα-ray from 10% to 70%.
2. The method of manufacturing a positive active material for a lithium secondary battery according to claim 1 , wherein the sintering temperature is from 970 to 980° C.
3. The method of manufacturing a positive active material for a lithium secondary battery according to claim 1 , wherein the positive active material has a ratio of diffracted intensity of diffraction lines in 2θ=45° (104 plane) with respect to diffracted intensity of diffraction lines in the vicinity of 2θ=18° (003 plane) in X-ray diffraction patterns using a CuKα-ray from 20% to less than 40%.
4. The method of manufacturing a positive active material for a lithium secondary battery according to claim 1 , wherein the positive active material has a half width of diffraction lines in 2θ=18° to 20° (003 plane) from 0.08 to 0.16 in X-ray diffraction patterns using a CuKα-ray.