Negative active material for rechargeable lithium battery, method of preparing same and rechargeable lithium battery including same

Patent metadata

Field	Value
Publication number	US-10205162-B2
Application number	US-201514980714-A
Country	US
Kind code	B2
Filing date	Dec 28, 2015
Priority date	Jan 15, 2015
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

A negative active material for a rechargeable lithium battery, a method of preparing a negative active material for a rechargeable lithium battery, and a rechargeable lithium battery, the negative active material including a silicon-graphite composite, wherein the silicon-graphite composite includes a graphite particle, a silicon particle inside the graphite particle, and amorphous carbon inside the graphite particle.

First claim

What is claimed is:

1. A negative active material for a rechargeable lithium battery, the negative active material comprising a silicon-graphite composite,
wherein the silicon-graphite composite includes:
a graphite particle,
a silicon particle inside the graphite particle,
a silicon particle on a surface of the graphite particle, and
amorphous carbon inside the graphite particle,

wherein an amount of the silicon particle inside the graphite particle is about 30 wt % to about 70 wt %, based on a total weight of the silicon particles present inside and on the surface of the graphite particle.

2. The negative active material for a rechargeable lithium battery as claimed in claim 1 , wherein a total amount of the silicon particle present inside and on the surface of the graphite particle is about 15 wt % to about 60 wt %, based on a total weight of the silicon-graphite composite.

3. The negative active material for a rechargeable lithium battery as claimed in claim 1 , wherein the graphite particle includes expanded graphite.

4. The negative active material for a rechargeable lithium battery as claimed in claim 1 , wherein the amorphous carbon inside the graphite particle is included in an amount of about 5 wt % to about 40 wt %, based on a total weight of the silicon-graphite composite.

5. The negative active material for a rechargeable lithium battery as claimed in claim 1 , further comprising a coating layer surrounding the silicon-graphite composite, wherein the coating layer includes amorphous carbon.

6. The negative active material for a rechargeable lithium battery as claimed in claim 1 , wherein the negative active material has a specific surface area of about 1 m 2 /g to about 10 m 2 /g.

7. A rechargeable lithium battery comprising a negative electrode, the negative electrode including the negative active material as claimed in claim 1 .

8. A method of preparing the negative active material for a rechargeable lithium battery as claimed in claim 1 , the method comprising:
mixing a graphite particle raw material, a silicon particle raw material, and an amorphous carbon raw material to obtain a silicon-graphite composite precursor; and
compression-forming the silicon-graphite composite precursor to obtain the silicon-graphite composite.

9. The method as claimed in claim 8 , wherein the compression-forming includes pressing the silicon-graphite composite precursor at a pressure of about 2 MPa to about 10 MPa.

10. The method as claimed in claim 8 , wherein the graphite particle includes expanded graphite.

11. The method as claimed in claim 10 , wherein the expanded graphite is prepared by performing an expansion process for about 1 hour to about 20 hours.

12. The method as claimed in claim 8 , further comprising:
mixing the silicon-graphite composite and amorphous carbon raw material to obtain a mixture; and
firing the mixture such that a coating layer is formed on the silicon-graphite composite.

13. The method as claimed in claim 8 , wherein:
the graphite particle has an average particle diameter of about 5μm to about 20 μm, and
the silicon particle has an average particle diameter of about 50 nm to about 300 nm.

14. The method as claimed in claim 8 , wherein the amorphous carbon raw material includes sucrose, methylene diphenyl diisocyanate, polyurethane, a phenolic resin, a naphthalene resin, polyvinyl alcohol, polyvinylchloride, furfuryl alcohol, polyacrylonitrile, polyamide, furan resin, cellulose, styrene, polyimide, an epoxy resin, a vinyl chloride resin, coal-based pitch, petroleum-based pitch, mesophase pitch, tar, low molecular weight heavy oil, or a combination thereof.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Youm Chul

Classifications

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title