Method of preparing negative active material containing a carbon-coated silicon core for a rechargeable lithium battery and a rechargeable lithium battery

• US 9,306,209 B2
• Filed: 01/14/2011
• Issued: 04/05/2016
• Est. Priority Date: 04/19/2010
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation), Ulsan National Institute of Science and Technology
• Original Assignee: LG Chem Limited (LG Corporation), Ulsan National Institute of Science and Technology
• Inventors: Cho, Jaephil, Seo, Min-Ho, Park, Mi-Hee, Kim, Hye-Jung, Kim, Ki-Tae, Kim, Je-Young
• Primary Examiner(s): Ruddock, Ula C
• Assistant Examiner(s): CHUO, TONY SHENG HSIANG
• Application Number:
  US13/006,921
• Publication Number:
  US 20110256452A1
• Time in Patent Office: 1,908 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides a method of preparing a negative active material for a rechargeable lithium battery, comprising the steps of: mixing a silicon precursor, a surfactant comprising an ammonium halide salt having a organic group, an initiator, and a solvent; heat-treating the mixture; cooling the heat-treated mixture to room temperature; washing the cooled, heat treated mixture; and calcining the washed product.

Claims

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

a) mixing a silicon precursor of silicon halide, a surfactant comprising an ammonium halide salt having an organic group, an initiator, and a solvent;

b) heat-treating the mixture to form a reverse micelle structure in which silicon particles are surrounded by the surfactant;

c) cooling the heat-treated mixture to room temperature;

d) washing the cooled, heat-treated mixture; and

e) calcining the washed product,

wherein the negative active material for the rechargeable lithium battery has a particle diameter of 3 nm to 30 nm,

wherein the negative active material for the rechargeable lithium battery comprises a core comprising silicon;

wherein the surfactant is degraded by the calcination; and

wherein carbon atoms derived from the calcined surfactant form a coating layer on the surface of the core.

2. The method according to claim 1, wherein the ammonium halide salt is represented by the following Chemical Formula 1:

3. The method according to claim 1, wherein the mixture comprises 50 to 70 weight % of the silicon precursor, to 20 weight % of the surfactant, 10 to 45 weight % of the initiator, and the remaining weight % of the solvent.

4. The method according to claim 1, wherein the initiator is sodium naphthalide.

5. The method according to claim 1, wherein the solvent is hexane, isopropyl alcohol, or a mixture thereof.

6. The method according to claim 1, wherein the heat-treatment is carried out at the temperature of 300°

C. to 500°

C.

7. The method according to claim 1, wherein the washing process is carried out by using hexane, water, or a mixture thereof.

8. The method according to claim 1, wherein the calcination step is carried out at a temperature of 600°

C. to 1000°

C.

9. The method according to claim 1, further comprising the step of coating the surface of the calcined product with carbon.

10. The method according to claim 1, wherein the particle diameter has a deviation of 2 nm or less.

11. The method according to claim 1, wherein the silicon in the core is crystalline and the carbon in the coating layer is amorphous.

12. The method according to claim 1, wherein the coating layer has a thickness of 0.5 nm to 5 nm.

13. The method according to claim 1, wherein the negative active material for the rechargeable lithium battery has a dispersity of 70 to 95%.