High voltage positive active material and method for preparing the same
Disclosed herein is a high voltage cathode active material and a method for preparing the same. The cathode active material includes particles of a spinel-type compound having a composition represented by Formula (1) and a carbon-based material present on surfaces of the particles of the spinel-type compound: Li 1+a M x Mn 2−x O 4−z A z (1) where −0.1≤a≤0.1, 0.3≤x≤0.8 and 0≤z≤0.1.
1. A cathode active material comprising:
particles of a spinel-type compound having a composition represented by Formula (2);
wherein the particles of the spinel-type compound has a material present on surfaces of the particles of the spinel-type compound, wherein the material consists of particles consisting of a carbon-based material:
Li 1+a Ni b M c Mn 2−(b+c) O 4−z A z (2)
where M is at least one selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and period II transition metals,
A is a monoanion or dianion, and
−0.1≤a≤0.1, 0.3≤b≤0.6, 0≤c≤0.2, and 0≤z≤0.1,
wherein the carbon-based material is physically and/or chemically bonded to the surfaces of the particles of the spinel-type compound of Formula (2),
wherein an average particle diameter (D50) of the carbon-based material is equal to or greater than 2 nm and equal to or less than 500 nm, and
the cathode active material is prepared by mixing the spinel-type compound of Formula (2) and a carbon precursor to form a resulting mixture, wherein the carbon precursor and the spinel-type compound are mixed using dry mixing, wherein the carbon precursor is petroleum-based pitch; and
thermally treating the resulting mixture at a temperature of 400 to 800° C. under an inert atmosphere or an oxygen deficient atmosphere with an oxygen concentration of 35% by volume or less.
2. The cathode active material according to claim 1 , wherein the carbon-based material covers equal to or greater than 20% and equal to or less than 100% of the entire surface of the spinel-type compound of Formula (2).
3. The cathode active material according to claim 2 , wherein the carbon-based material covers equal to or greater than 50% and equal to or less than 80% of the entire surface of the spinel-type compound of Formula (2).
4. A lithium secondary battery comprising the cathode active material according to claim 1 .
5. A battery pack comprising the lithium secondary battery according to claim 4 .
6. An electric vehicle comprising the battery pack according to claim 5 .
7. A method for preparing the cathode active material of claim 1 , the method comprising:
(1) mixing a spinel-type compound having a composition represented by Formula (2) and a carbon precursor,
wherein the carbon precursor and the spinel-type compound are mixed using dry mixing, wherein the carbon precursor is petroleum-based pitch;
(2) thermally treating the resulting mixture under an inert atmosphere or an oxygen deficient atmosphere with an oxygen concentration of 35% by volume or less:
Li 1+a Ni b M c Mn 2−(b+c) O 4−z A z (2)
where M is at least one selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and period II transition metals,
A is a monoanion or dianion, and
−0.1≤a≤0.1, 0.3≤b≤0.6, 0≤c≤0.2, and 0≤z≤0.1,
(3) resulting in the cathode active material of claim 1 .
8. The method according to claim 7 , wherein the thermal treatment is performed at a temperature of 400 to 800° C.
9. The method according to claim 7 , wherein the carbon precursor comprises at least one selected from the group consisting of petroleum-based pitch, tar, phenolic resin, furan resin and carbohydrate.
10. The method according to claim 7 , wherein the inert atmosphere is a nitrogen (N 2 ) or argon (Ar) atmosphere.