Cathode active material for lithium secondary battery and lithium secondary battery including the same
A cathode active material for a lithium secondary battery includes a lithium-aluminum-titanium oxide formed on a surface of a lithium metal oxide particle having a specific formula. The cathode active material may have an improved structural stability even in a high temperature condition.
1. A cathode active material for a lithium secondary battery, comprising:
a lithium metal oxide particle formed of a crystal of a compound represented by Formula 1 below; and
a lithium-aluminum-titanium oxide represented by Formula 2 below and formed on at least a part of a surface of the lithium metal oxide particle:
Li α Ni y M z O 2-β [Formula 1]
wherein, in the above Formula 1, M is at least one element selected from the group consisting of Co, Mn, Ti, Zr, Al and B, and α, β, y, and z are in a range of 0.7≤α≤1.1, −0.1≤β≤0.5, 0.7≤y≤0.95, and 0.95<y+z≤1.1, respectively
Li γ Al v Ti w O x [Formula 2]
wherein, in the above Formula 2, γ, v, w and x are in a range of 0.8<γ≤1.2, 0<v≤1, 0<w≤1, 0.98≤v+w≤1.02, and 1.5≤x≤4, respectively.
2. The cathode active material for a lithium secondary battery according to claim 1 , wherein, in the above Formula 1, M z is Co a Mn b M′ c , M′ is at least one element selected from the group consisting of Ti, Zr, Al and B, and a, b, c, and y are in a range of 0.05≤a≤0.2, 0.03≤b≤0.2, and 0.95<y+a+b+c≤1.1, respectively.
3. The cathode active material for a lithium secondary battery according to claim 2 , wherein, in the above Formula 1, a, b, c, and y are in a range of 0.8≤y≤0.88, 0.09≤a≤0.1, 0.03≤b≤0.1, respectively.
4. The cathode active material for a lithium secondary battery according to claim 1 , further comprising at least one of Al 2 O 3 and LiAlO 2 formed on the surface of the lithium metal oxide particle.
5. The cathode active material for a lithium secondary battery according to claim 1 , further comprising LiTiO 2 formed on the surface of the lithium metal oxide particle.
6. The cathode active material for a lithium secondary battery according to claim 1 , further comprising a zirconium (Zr)-including oxide formed on the surface of the lithium metal oxide particle.
7. The cathode active material for a lithium secondary battery according to claim 6 , wherein the zirconium including oxide includes AlZrO.
8. The cathode active material for a lithium secondary battery according to claim 1 , further comprising a boron (B)-including oxide formed on the surface of the lithium metal oxide particle.
9. The cathode active material for a lithium secondary battery according to claim 8 , wherein the boron including oxide includes at least one selected from the group consisting of B 4 O 10 , AlBO 3 and Li 2 B 4 O 7 .
10. The cathode active material for a lithium secondary battery according to claim 1 , wherein the lithium-aluminum-titanium oxide is formed by dry-mixing the lithium metal oxide particle with Al 2 O 3 and TiO 2 having a particle diameter of 30 to 70 nm, respectively, under a high temperature condition, then performing oxygenation.
11. The cathode active material for a lithium secondary battery according to claim 10 , wherein the dry-mixing is performed by further including at least one of ZrO 2 and H 3 BO 3 .
12. The cathode active material for a lithium secondary battery according to claim 11 , wherein Al 2 O 3 , TiO 2 , ZrO 2 and H 3 BO 3 are used in an amount of 2500 to 3500 ppm, 500 to 1500 ppm, 300 to 700 ppm, and 300 to 700 ppm, respectively, based on a weight of the lithium metal oxide particle.
13. The cathode active material for a lithium secondary battery according to claim 11 , wherein the ZrO 2 has a particle diameter of 70 to 130 nm.
14. The cathode active material for a lithium secondary battery according to claim 11 , wherein the lithium-aluminum-titanium oxide is formed by dry-mixing the lithium metal oxide particle with Al 2 O 3 , TiO 2 and ZrO 2 under a high temperature condition and performing oxygenation, then further dry-mixing H 3 BO 3 therewith under a high temperature condition and performing oxygenation.
15. The cathode active material for a lithium secondary battery according to claim 14 , wherein the Al 2 O 3 , TiO 2 and ZrO 2 are mixed at a temperature of 600 to 800° C. and the H 3 BO 3 is mixed at a temperature of 250 to 330° C.
16. The cathode active material for a lithium secondary battery according to claim 1 , wherein the lithium metal oxide particle and the lithium-aluminum-titanium oxide are formed by dry-mixing a composite metal salt compound, a lithium salt compound, and Al 2 O 3 and TiO 2 having a particle diameter of 30 to 70 nm, respectively, under a high temperature condition and performing oxygenation.
17. The cathode active material for a lithium secondary battery according to claim 1 , wherein at least a part of the surface of the lithium metal oxide particle is coated with the lithium-aluminum-titanium oxide.
18. A lithium secondary battery comprising:
an electrode assembly including a cathode made of the cathode active material for a lithium secondary battery according to claim 1 , an anode, and a separation membrane disposed between the cathode and the anode;
a case in which the electrode assembly is housed; and
an electrolyte in which the electrode assembly is impregnated in the case.