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

Patent metadata

Field	Value
Publication number	US-9306209-B2
Application number	US-201113006921-A
Country	US
Kind code	B2
Filing date	Jan 14, 2011
Priority date	Apr 19, 2010
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

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.

First claim

We claim:

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:

wherein,
R 1 , R 2 , R 3 , and R 4 are the same or different from each other, and independently represent hydrogen, or a C 1 -C 30 aliphatic organic group, and
X is F, Cl, Br, or I.

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%.

Assignees

• Cho Jaephil
• Seo Min-Ho
• Park Mi-Hee
• Kim Hye-Jung
• Kim Ki-Tae
• Kim Je-Young
• Ulsan Nat Inst Of Science And Technology
• Lg Chemical Ltd

Inventors

• Cho Jaephil
• Seo Min-Ho
• Park Mi-Hee
• Kim Hye-Jung
• Kim Ki-Tae
• Kim Je-Young

Classifications

• Y02E60/122

  Cross-Sectional Technologies · mapped topic

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M4/38

  of elements or alloys · CPC title

• H01M4/366 Primary

  as layered products · CPC title