Carbon compound-adsorbed cathode active material and lithium battery using the same
A cathode active material is prepared by mixing a transition metal compound and a lithium compound in a molar ratio of 1:1.0-1:1.2 and thermally treating the mixture while supplying CO 2 and O 2 in a ratio of partial pressures ranging from 1:0.001-1:1,000, and a lithium battery utilizes the cathode active material. The lithium battery ensures safety against over-charging because an overflow of current may be effectively cut off without reducing discharging capacity and cycle life characteristics.
1. A cathode active material comprising:
a lithium transition metal composite oxide in which a carbon compound is adsorbed to obtain a carbon content of 10-1,000 ppm.
2. The cathode active material of claim 1 , wherein the lithium transition metal composite oxide is at least one selected from the group consisting of LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiFePO 4 , LiNi x Co 1-x O 2 where 0<x<1, and LiNi 1-x-y Co x Mn y O 2 where 0<x<1, 0<y<1, and 0<x+y<1.
3. The cathode active material of claim 1 , wherein the carbon compound has a specific surface area of 10-5,000 m 2 /g.
4. A lithium battery comprising:
a cathode comprising:
a cathode active material that comprises a lithium transition metal composite oxide in which a carbon compound is adsorbed to obtain a carbon content of 10-1,000 ppm;
an anode comprising a carbonaceous material to facilitate intercalating and deintercalating lithium ions;
a separator interposed between the cathode and the anode;
an electrolytic solution containing an electrolytic solute dissolved in a nonaqueous solvent; and
a current cut-off device that operates in response to a rise in an internal pressure of the lithium battery.
5. The lithium battery of claim 4 , wherein the carbon compound has a specific surface area of 10-5,000 m 2 /g.
6. The lithium battery of claim 4 , wherein the separator is selected from the group consisting of a glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene, and a combination of thereof.
7. A lithium battery comprising:
a cathode comprising:
a cathode active material that comprises a lithium transition metal composite oxide in which a carbon compound is adsorbed to obtain a carbon content of 10-1,000 ppm and wherein the lithium transition metal composite oxide is at least one selected from the group consisting of LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiFePO 4 , LiNi x Co 1-x O 2 where 0<x<1, and LiNi 1-x-y Co x Mn y O 2 where 0<x<1, 0<y<1, and 0<x+y<1;
an anode comprising a carbonaceous material to facilitate intercalating and deintercalating lithium ions;
a separator interposed between the cathode and the anode;
an electrolytic solution containing an electrolytic solute dissolved in a nonaqueous solvent; and
a current cut-off device that operates in response to a rise in an internal pressure of the lithium battery.
8. The lithium battery of claim 7 , wherein a polymer resin is utilized as a binding agent for the anode and the cathode, and wherein the polymer resin is a vinylidenefluoride-hexafluoropropylene copolymer having 8-25% by weight of hexafluoropropylene.