Anode active material for lithium secondary battery, preparation method therefor, and lithium secondary battery containing same

Patent metadata

Field	Value
Publication number	US-10340518-B2
Application number	US-201615737040-A
Country	US
Kind code	B2
Filing date	Jun 15, 2016
Priority date	Jun 15, 2015
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

An anode active material for a lithium secondary battery, a preparation method thereof, and a lithium secondary battery including the anode active material are provided. The anode active material includes carbon particles having a spherical shape, a first carbon coating layer present on surfaces of the carbon particles, a silicon coating layer present on the first carbon coating layer and including silicon nanoparticles, and a second carbon coating layer present on the silicon coating layer.

First claim

The invention claimed is:

1. An anode active material for a lithium secondary battery, comprising:
carbon particles having a spherical shape;
a first carbon coating layer present on surfaces of the carbon particles;
a silicon coating layer present on the first carbon coating layer and including silicon nanoparticles; and
a second carbon coating layer present on the silicon coating layer.

2. The anode active material of claim 1 , wherein the carbon particles having the first carbon coating layer thereon have an about 10% or greater increased Brunauer-Emmett-Teller (BET) specific surface area with respect to a BET specific surface area of the carbon particles having the spherical shape.

3. The anode active material of claim 1 , wherein the carbon particles having the first carbon coating layer thereon have an about 10% or greater decreased Brunauer-Emmett-Teller (BET) specific surface area with respect to a BET specific surface area of the carbon particles having the spherical shape.

4. The anode active material of claim 1 , wherein the silicon nanoparticles are semicrystalline.

5. The anode active material of claim 1 , wherein the first carbon coating layer partially includes a mixed layer of silicon and carbon.

6. The anode active material of claim 5 , wherein the mixed layer of silicon and carbon layer has a concentration gradient in which an amount of silicon decreases in the direction of a core.

7. The anode active material of claim 1 , wherein the silicon coating layer present on the first carbon coating layer is in a mixed form of a film and an island.

8. The anode active material of claim 1 , wherein a content ratio of silicon to carbon is 3:97 to 20:80, with respect to a total weight of the anode active material.

9. The anode active material of claim 1 , wherein the anode active material includes 2 wt % to 6 wt % of the first carbon coating layer, 4 wt % to 20 wt % of the silicon coating layer, and 1.5 wt % to 10 wt % of the second carbon coating layer, each based on a total of 100 wt % of the anode active material, and the remainder is the carbon particles.

10. The anode active material of claim 1 , wherein the carbon particles comprise graphite, amorphous carbon, or a combination thereof.

11. The anode active material of claim 1 , wherein the carbon particles have a particle diameter of 5 μm to 20 μm.

12. The anode active material of claim 1 , wherein the first carbon coating layer has a thickness of 5 nm to 200 nm.

13. The anode active material of claim 1 , wherein the silicon coating layer has a thickness of 20 nm to 60 nm.

14. The anode active material of claim 1 , wherein the second carbon coating layer has a thickness of 5 nm to 200 nm.

15. A lithium secondary battery comprising:
a cathode;
an anode; and
an electrolyte,
wherein the anode comprises the anode active material of claim 1 .

16. A method of preparing an anode active material for a lithium secondary battery, the method comprising:
preparing carbon particles having a spherical shape;
forming a first carbon coating layer on surfaces of the carbon particles;
forming, on the first carbon coating layer, a silicon coating layer including silicon nanoparticles; and
forming a second carbon coating layer on the silicon coating layer.

17. The method of claim 16 , wherein the forming of the first carbon coating layer on the surfaces of the carbon particles is performed using a sol-gel method.

18. The method of claim 16 , wherein the forming of the first carbon coating layer on the surfaces of the carbon particles is performed using a chemical vapor deposition method.

19. The method of claim 16 , wherein, in the forming of the silicon coating layer including silicon nanoparticles on the first carbon coating layer, the silicon nanoparticles are amorphous.

20. The method of claim 16 , wherein, in the forming of the silicon coating layer including silicon nanoparticles on the first carbon coating layer, the silicon coating layer is deposited in a mixed form of a film and an island.

21. The method of claim 16 , wherein the forming of the second carbon coating layer on the silicon coating layer is performed using a physical milling method, a sol-gel method, or a chemical vapor deposition method.

Assignees

• Ulsan Nat Inst Science & Tech Unist

Inventors

• Cho Jaephil
• Ko Min Seong
• Chae Su Jong
• Ma ji young
• Kim Nam Hyung

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/364

  as mixtures · CPC title

• C01B33/029 Primary

  by decomposition of monosilane · CPC title