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

Patent metadata

Field	Value
Publication number	US-2021313557-A1
Application number	US-202117354060-A
Country	US
Kind code	A1
Filing date	Jun 22, 2021
Priority date	Sep 24, 2015
Publication date	Oct 7, 2021
Grant date	—

Abstract

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiO a (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

1 . A negative electrode active material, comprising:
a silicon-based composite represented by SiO a (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite; wherein the silicon-based composite includes amorphous silicon.

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

3 . The negative electrode active material according to claim 1 , wherein the silicon-based composite further includes a crystalline silicon oxide.

4 . The negative electrode active material according to claim 2 , wherein an amount of the crystalline silicon in the silicon-based composite is 10 wt % or less based on the total weight of silicon.

5 . The negative electrode active material according to claim 1 , wherein a thickness of the carbon coating layer is in a range of 0.003 to 3.0 μm.

6 . The negative electrode active material according to claim 1 , wherein an average particle diameter of the negative electrode active material is in a range of 0.1 to 20 μm.

7 . The negative electrode active material according to claim 1 , wherein an average particle diameter of the negative electrode active material is in a range of 0.5 to 10 μm.

8 . The negative electrode active material 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.

9 . The negative electrode active material according to claim 1 , wherein the carbon coating layer includes one or more selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fibers and carbon black.

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

11 . The negative electrode active material according to claim 1 , wherein the negative electrode active material is formed by a method including:
forming a carbon coating layer on a silicon-based precursor represented by SiO x (0<x<2); 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, the thermal treatment includes thermally reducing a silicon-based precursor with a metal reducing agent in an inert atmosphere, and the thermal treatment is performed in a temperature range of 350 to 650° C.

12 . The negative electrode active material according to claim 11 , wherein the thermal treatment is performed in a rotary kiln.

13 . The negative electrode active material according to claim 11 , wherein the metal reducing agent includes one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof.

14 . The negative electrode active material according to claim 11 , 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.

15 . The negative electrode active material according to claim 11 , wherein the preparing of the silicon-based composite includes removing impurities using an acidic aqueous solution.

16 . The negative electrode active material according to claim 11 , wherein the acidic aqueous solution includes one or more selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid.

17 . The negative electrode active material according to claim 11 , 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.

18 . A negative electrode comprising the negative electrode active material of claim 1 .

19 . A secondary battery comprising the negative electrode of claim 18 .

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