NEGATIVE ACTIVE MATERIAL FOR RECHARGEABLE LITHIUM BATTERY, METHOD FOR PREPARING SAME, AND RECHARGEABLE LITHIUM BATTERY INCLUDING SAME

• US 20140342235A1
• Filed: 01/07/2014
• Published: 11/20/2014
• Est. Priority Date: 05/15/2013
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Park, Sung Soo, Lee, Sang-Hun, Cha, Jun-Kyu, Kim, Ki-Jun, Kim, Jae-Myung, Song, Su-Bin, Lee, Eun-Cheol, Shim, Jae-Hyun
• Granted Patent: US 9,496,548 B2
• Time in Patent Office: Days
• US Class Current: 429/231.8
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/139 Processes of manufacture
• CPC Class Codes: H01M 4/362 Composites
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Disclosed are a negative active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery including the same. The negative active material includes a composite particle including a silicon particle and a carbon coating layer coated on the surface of the silicon particle and a porous space formed by the entangled carbon nanofibers, the composite particle contacting the external surface of the carbon nanofibers in the porous space of the carbon nanofiber structure, and the carbon nanofibers have a larger diameter than that of the composite particle and a diameter ranging from about 100 nm to about 2000 nm.

Claims

1. A negative active material for a rechargeable lithium battery, comprising:

a composite particle comprising a silicon particle and a carbon coating layer coated on the surface of the silicon particle; and

a carbon nanofiber structure comprising a porous space formed by entangled carbon nanofibers,

wherein the composite particle contacts the external surface of the carbon nanofibers in the porous space of the carbon nanofiber structure, and

the carbon nanofiber has a diameter ranging from about 100 nm to about 2000 nm and a larger diameter than that of the composite particle.

2. The negative active material of claim 1, wherein the carbon nanofiber has a diameter that is about 2 times to about 200 times larger than that of the composite particle.

3. The negative active material of claim 1, wherein a diameter of the silicon particle ranges from about 5 nm to about 300 nm.

4. The negative active material of claim 1, wherein the porous space has a diameter ranging from about 5 nm to about 500 nm.

5. The negative active material of claim 1, wherein the silicon particle is included in an amount of about 1 part to about 25 parts by weight based on 100 parts by weight of the carbon nanofiber.

6. The negative active material of claim 1, wherein an amount of the composite particle ranges from about 25 wt % to about 98 wt % based on the total amount of the negative active material.

7. The negative active material of claim 1, wherein an amount of the carbon nanofiber ranges from about 2 wt % to about 75 wt % based on the total amount of the negative active material.

8. The negative active material of claim 1, wherein the composite particle is present in an inner space of the carbon nanofibers.

9. A method of preparing the negative active material for a rechargeable lithium battery comprising:

preparing a polymer solution by mixing polyacrylonitrile, 1-methoxy-2-propanol acetate, and a silicon particle;

preparing a carbon nanofiber structure including the silicon particle dispersed therein by electrospinning the polymer solution at about 5 kV to about 20 kV; and

carbonizing the carbon nanofiber structure that includes the silicon particle dispersed therein.

10. The method of claim 9, wherein the polymer solution comprises the polyacrylonitrile, the 1-methoxy-2-propanol acetate and the silicon particle at weight ratios from about 40 to 70:

from about 10 to 35;

from about 1 to 25.

11. The method of claim 9, wherein the carbonizing process is performed at a temperature ranging from about 500°

C. to about 1500°

C.

12. The method of claim 9, which further comprises stabilization of the carbon nanofiber structure including the silicon particle dispersed therein between the electrospinning and the carbonizing processes.

13. The method of claim 12, wherein the stabilization is performed at a temperature ranging from about 200°

C. to about 1000°

C.

14. A rechargeable lithium battery, comprising:

a negative electrode including a negative active material comprising a composite particle comprising a silicon particle and a carbon coating layer coated on the surface of the silicon particle; and

a carbon nanofiber structure comprising a porous space formed by entangled carbon nanofibers, wherein the composite particle contacts the external surface of the carbon nanofibers in the porous space of the carbon nanofiber structure, and the carbon nanofiber has a diameter ranging from about 100 nm to about 2000 nm and a larger diameter than that of the composite particle;

a positive electrode including a positive active material; and

an electrolyte.

15. The rechargeable lithium battery of claim 14, wherein the carbon nanofiber of the negative active material has about 2 times to about 200 times a larger diameter than that of the composite particle.

16. The rechargeable lithium battery of claim 14, wherein a diameter of the silicon particle of the negative active material ranges from about 5 nm to about 300 nm.

17. The rechargeable lithium battery of claim 14, wherein the porous space has a diameter ranging from about 5 nm to about 500 nm.

18. The rechargeable lithium battery of claim 14, wherein the silicon particle of the negative active material is included in an amount of about 1 part to about 25 parts by weight based on 100 parts by weight of the carbon nanofiber.

19. The rechargeable lithium battery of claim 14, wherein an amount of the composite particle of the negative active material ranges from about 25 wt % to about 98 wt % based on the total amount of negative active material.

20. The rechargeable lithium battery of claim 14, wherein an amount of the carbon nanofiber of the negative active material ranges from about 2 wt % to about 75 wt % based on the total amount of the negative active material.