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

Patent metadata

Field	Value
Publication number	US-2018151874-A1
Application number	US-201615577233-A
Country	US
Kind code	A1
Filing date	Sep 23, 2016
Priority date	Sep 24, 2015
Publication date	May 31, 2018
Grant date	—

Abstract

The present specification relates to a negative electrode active material which includes 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, and which has a bimodal pore structure including nanopores and mesopores. In a lithium secondary battery including the negative electrode active material, an oxygen content in the silicon-based composite can be controlled to improve initial efficiency and capacity characteristics, and a specific surface area can also be controlled, and thus a side reaction with electrolyte can be reduced.

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 has a bimodal pore structure including mesopores and macropores.

2 . The negative electrode active material according to claim 1 , wherein the silicon-based composite has the bimodal pore structure formed entirely from an inner central portion to a surface portion of the silicon-based composite.

3 . The negative electrode active material according to claim 1 , wherein a diameter of the mesopore is in a range of 2 to 50 nm.

4 . The negative electrode active material according to claim 1 , wherein a diameter of the macropore is in a range of 50 to 700 nm.

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 a specific surface area of the negative electrode active material is in a range of 1 to 20 m 2 /g.

7 - 8 . (canceled)

9 . 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); 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 has a bimodal pore structure including mesopores and macropores.

10 . (canceled)

11 . The method according to claim 9 , 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.

12 . The method according to claim 9 , wherein the thermal treatment includes thermally reducing a silicon-based precursor with a metal reducing agent in an inert atmosphere.

13 . The method according to claim 9 , wherein the thermal treatment is performed in a temperature range of 650 to 900° C.

14 . (canceled)

15 . The method according to claim 12 , wherein the metal reducing agent includes one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof

16 . The method according to claim 12 , 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.

17 . The method according to claim 9 , wherein the preparing of the silicon-based composite includes removing impurities using an acidic aqueous solution.

18 . (canceled)

19 . The method according to claim 9 , 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.

20 . A secondary battery comprising the negative active material of claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

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

Classifications

• B01J13/20

  After-treatment of capsule walls, e.g. hardening · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title