Si/C composite, method of preparing the same, and anode active material for lithium secondary battery including the Si/C composite

Patent metadata

Field	Value
Publication number	US-9831491-B2
Application number	US-201414272636-A
Country	US
Kind code	B2
Filing date	May 8, 2014
Priority date	Feb 19, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

Provided are a Si/C composite, in which carbon (C) is dispersed in an atomic state in a silicon (Si) particle, and a method of preparing the Si/C composite.
Since the Si/C composite of the present invention is used as an anode active material, electrical conductivity may be further improved and volume expansion may be minimized. Thus, life characteristics of a lithium secondary battery may be improved.

First claim

The invention claimed is:

1. A method of preparing a Si/C composite, the method comprising:
i) mixing an aromatic group-containing silicon alkoxide compound expressed by Chemical Formula 1 with an organic solvent to form a SiO 2 /C composite;
ii) mixing the SiO 2 /C composite obtained in step i) with an alkali metal or an alkaline earth metal and heat treating the mixture in an inert atmosphere to reduce SiO 2 ; and
iii) acid treating the heat-treated product obtained in step ii) to remove an oxide,
SiR 1 n R 2 4−n   <Chemical Formula 1>

wherein
R 1 is a phenyl group,
R 2 is an alkoxy group of C 1 to C 4 , and
n is 1 to 3,
wherein carbon in the SiO 2 /C composite is generated from the aromatic group-containing silicon alkoxide compound, and
wherein an amount of the carbon in the SiO 2 /C composite is adjusted according to an amount of the aromatic group-containing silicon alkoxide compound.

2. The method of claim 1 , wherein the aromatic group-containing silicon alkoxide compound is any one selected from phenyltriethoxysilane (PTES), phenyltrimethoxysilane (PTMS), diphenyldiethoxysilane (DDES), or a mixture of two or more thereof.

3. The method of claim 2 , wherein the aromatic group-containing silicon alkoxide compound is PTES.

4. The method of claim 1 , wherein an amount of the aromatic group-containing silicon alkoxide compound is in a range of 0.1 parts by weight to 20 parts by weight based on the organic solvent.

5. The method of claim 1 , further comprising adding a linear silicon alkoxide compound to the organic solvent in step i).

6. The method of claim 5 , wherein the linear silicon alkoxide compound is any one selected from tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), tetrapropyl orthosilicate (TPOS), tetrabutyl orthosilicate (TBOS), or a mixture of two or more thereof.

7. The method of claim 6 , wherein the linear silicon alkoxide compound is TEOS or TMOS.

8. The method of claim 5 , wherein a mixing ratio of the aromatic group-containing silicon alkoxide compound to the linear silicon alkoxide compound is in a range of 1:0.3 to 1:60 as a molar ratio.

9. The method of claim 1 , wherein the alkali metal is lithium, sodium, potassium, rubidium, cesium, or francium.

10. The method of claim 1 , wherein the alkaline earth metal is beryllium, magnesium, calcium, strontium, barium, or radium.

11. The method of claim 1 , wherein the heat treatment of step ii) is performed in a temperature range of 350° C. to 1400° C.

12. The method of claim 1 , further comprising coating a surface of the Si/C composite with carbon by mixing the Si/C composite with a carbon precursor after step iii).

13. The method of claim 12 , wherein the coating is performed in a temperature range of 300° C. to 1400° C.

14. The method of claim 12 , wherein the carbon precursor is pitch or a hydrocarbon-based material.

Assignees

• Lg Chemical Ltd

Inventors

• Ryu Ji Hoon
• Park Hong Kyu
• Jung Wang Mo
• Kang Sung Joong
• Jo Chi Ho
• Han Gi Beom

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M4/1395

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

• H01M4/386

  Silicon or alloys based on silicon · CPC title