Cathode active material for lithium secondary battery
View Patent ↗Disclosed herein is a cathode active material based on lithium nickel-manganese-cobalt oxide represented by Formula 1, wherein the lithium nickel-manganese-cobalt oxide has nickel content of at least 40% among overall transition metals and is coated with an ion-conductive solid compound at a surface thereof. A lithium secondary battery having the disclosed cathode active material has advantages of not deteriorating electrical conductivity while maintaining high temperature stability, so as to efficiently provide high charge capacity.
1. A cathode active material, comprising:
cathode active material particles comprising a lithium nickel-manganese-cobalt oxide represented by Formula (1), wherein the lithium nickel-manganese-cobalt oxide has nickel content of at least 40% among overall transition metals wherein the cathode active material particles are coated with a lithium phosphate at a surface thereof:
Li x M y O 2 (1)
wherein M is Ni 1-a-b Mn a Co b (0.05≦a≦0.4, 0.1≦b≦0.4, 0.4≦(1-a-b)≦0.9), x+y is about 2 and 0.95≦x≦1.15, and
the cathode active material and the lithium phosphate are present in a relative ratio by weight of 100:1 to 100:2.
2. The cathode active material according to claim 1 , wherein the cathode active material particles comprise particles with an agglomerated structure consisting of an aggregate of micro fine particles.
3. The cathode active material according to claim 1 , wherein the cathode active material particles comprise particles have an average particle diameter D50 of 3 to 20.
4. The cathode active material according to claim 2 , wherein the microfine particles have an average particle diameter D90 of 0.01 to 8 μm.
5. The cathode active material according to claim 1 , wherein the lithium phosphate is thoroughly or partially applied to a surface of cathode active material particles.
6. The cathode active material according to claim 1 , wherein 20 to 80% of an overall surface of the cathode active material particles is coated with the lithium phosphate.
7. The cathode active material according to claim 1 , wherein a coating thickness of the lithium phosphate ranges from 0.01 to 10 μm.
8. A lithium secondary battery including the cathode active material as set forth in claim 1 .
9. The lithium secondary battery according to claim 8 , wherein the lithium secondary battery is used as a power supply for a power tool, an electric vehicle, an electric two-wheel vehicle and/or an electric golf cart.
10. A cathode prepared by coating a slurry of the cathode active material of claim 1 , a conductive material, and a binder onto a cathode collector.
11. The lithium secondary battery according to claim 8 , wherein the battery comprises a cathode, an anode, a separator between the cathode and the anode, and a non-aqueous electrolyte containing lithium salt, in which the cathode is formed by coating the cathode active material onto a cathode collector.