Anode active material, method of preparing the same, and anode and lithium battery containing the material

1. An anode active material, comprising:

a graphite core; and

a first coating layer formed on the surface of the graphite core; and

a second coating layer formed on the surface of the first coating layer,

wherein the first coating layer comprises silicon microparticles coated with a first carbon film, and the second coating layer comprises carbon fiber coated with a second carbon film,

wherein the carbon fiber is separated from the graphite core and the silicon microparticles, and

wherein the average particle size of the silicon microparticles is about 0.01 μm to about 1 μm.

2. The anode active material of claim 1 ,

wherein the second coating layer is coated on the first coating layer.

3. The anode active material of claim 1 ,

wherein the silicon microparticles of the first coating layer are present on the surface of the graphite core.

4. The anode active material of claim 1 , further comprising: silicon microparticles within the graphite core.

5. The anode active material of claim 1 , wherein the first coating layer is about 0.1 μm to about 3 μm thick, on average.

6. The anode active material of claim 1 , wherein the second coating layer excluding the portion occupied by carbon fibers is about 0.1 μm to about 3 μm thick, on average.

7. The anode active material of claim 1 ,

wherein the average diameter of the carbon fibers is about 0.01 μm to about 1 μm.

8. The anode active material of claim 1 ,

wherein the aspect ratio of the carbon fibers is about 10 to about 200.

9. The anode active material of claim 1 ,

wherein the carbon fibers are fabricated by vapor grown method.

10. The anode active material of claim 1 ,

wherein the concentration of the silicon microparticles is about 3 wt % to about 15 wt % based on the total weight of the anode active material.

11. The anode active material of claim 1 ,

wherein the concentration of the carbon fibers is about 0.1 wt % to about 20 wt % based on the total weight of the anode active material.

12. The anode active material of claim 1 ,

wherein the first coating layer and the second coating layer comprise low crystalline carbon with an interlayer spacing of 3.45 Å or higher, or amorphous carbon.

13. An anode, comprising the anode active material of claim 1 .

14. A lithium battery, comprising the anode comprising the anode active material of claim 1 .

15. The anode active material of claim 1 , wherein the first carbon film and the second carbon film have face-to-face dimensions of at least 3.45 Å.

16. The anode active material of claim 1 , wherein the carbon fiber is not within the first carbon film.