Negative electrode active material for lithium secondary battery and method of preparing the same

Patent metadata

Field	Value
Publication number	US-11075369-B2
Application number	US-201615576992-A
Country	US
Kind code	B2
Filing date	Sep 23, 2016
Priority date	Sep 24, 2015
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiOa (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite, and provides a negative electrode active material in which the crystal growth of crystalline silicon in a silicon-based composite prepared by thermal reduction with a metal reducing agent is suppressed in a state where a carbon coating layer is formed, and the ratio of silicon in the composite is high, and a method of preparing the same.

First claim

The invention claimed is:

1. A method of preparing a negative electrode active material, comprising:
forming a carbon coating layer on a silicon-based precursor represented by SiO x (0<x<2) by flowing acetylene gas and argon gas over the silicon-based precursor;
thermally treating the silicon-based precursor on which the carbon coating layer is formed; and
preparing a silicon-based composite represented by SiO a (0<a<1) and having a surface on which a carbon coating layer is distributed by removing impurities;
wherein the silicon-based composite includes an amorphous silicon,
wherein the thermal treatment includes thermally reducing a silicon-based precursor with a metal reducing agent in an inert atmosphere, and
wherein the thermal treatment is performed in a temperature range of 350 to 650° C.

2. The method according to claim 1 , wherein the silicon-based composite further includes crystalline silicon having a crystal size of 10 nm or less.

3. The method according to claim 1 , wherein a content of the carbon coating layer is in a range of 1 to 50 wt % of a total weight of the negative electrode active material.

4. The method according to claim 1 , wherein the metal reducing agent includes one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof.

5. The method according to claim 1 , wherein a molar ratio of the silicon-based precursor to the metal reducing agent is in a range of 1:0.001 to 1:1.

6. The method according to claim 1 , wherein the preparing of the silicon-based composite includes removing impurities using an acidic aqueous solution.

7. The method according to claim 1 , wherein the impurities include one or more materials selected from the group consisting of a metal oxide, a metal silicide and a metal silicate, and the metal is one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof.

8. A method of preparing a negative electrode active material, comprising:
forming a carbon coating layer on a silicon-based precursor represented by SiO x (0<x<2),
wherein the carbon coating layer is formed by (1) dispersing a carbon precursor in a solvent to form a mixture, adding the mixture to the silicon-based precursor, and performing drying; and (2) performing first thermal treatment of the silicon-based precursor;
performing second thermal treatment of the silicon-based precursor on which the carbon coating layer is formed; and
preparing a silicon-based composite represented by SiO a (0<a<1) and having a surface on which a carbon coating layer is distributed by removing impurities;
wherein the silicon-based composite includes an amorphous silicon,
wherein the second thermal treatment includes thermally reducing a silicon-based precursor with a metal reducing agent in an inert atmosphere, and
wherein the second thermal treatment is performed in a temperature range of 350 to 650° C.

Assignees

• Lg Chemical Ltd

Inventors

• Kim Hyun Chul
• Lee Yong Ju
• Kim Eun Kyung

Classifications

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/134 Primary

  Electrodes based on metals, Si or alloys · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M10/052

  Li-accumulators · CPC title