Negative electrode active material for lithium secondary battery, preparation method therefor, and lithium secondary battery comprising same

Patent metadata

Field	Value
Publication number	US-11515520-B2
Application number	US-201816630175-A
Country	US
Kind code	B2
Filing date	Jul 10, 2018
Priority date	Jul 12, 2017
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

The present invention relates to a negative active material for a lithium secondary battery, a preparation method therefor, and a lithium secondary battery including the same. The negative electrode active material is a negative electrode material for a secondary battery, the negative electrode active material comprising a silicon-carbon composite comprising: a core comprising crystalline carbon and silicon particles; and an amorphous carbon-containing coating layer disposed on a surface of the core, wherein the negative electrode active material comprises: silicon oxide formed on a surface of the silicon particles; and an oxide of crystalline carbon, formed on a surface of the crystalline carbon, the average particle diameter (D50) of the silicon particles having a nanometer size, the proportion of O relative to Si in the silicon oxide is 30%-50%, and the proportion of O relative to C in the oxide of the crystalline carbon is 4%-10%.

First claim

The invention claimed is:

1. A negative active material for a lithium secondary battery comprising a silicon-carbon composite including a core including crystalline carbon and silicon particles and an amorphous carbon-containing coating layer disposed on a surface of the core,
wherein:
the negative active material comprises:
a silicon oxide formed on a surface-of the silicon particles, and
an oxide of crystalline carbon formed on a surface of the crystalline carbon,

an average particle diameter (D50) of the silicon particles has a nanometer size,
a ratio of 0 relative to Si in the silicon oxide is 30 wt % to 50 wt %, and
a ratio of 0 relative to C in the oxide of the crystalline carbon is 4 wt % to 10 wt %.

2. The negative active material of claim 1 , wherein the average diameter (D50) of the silicon particles is 5 nm to 500 nm.

3. The negative active material of claim 1 , wherein a content of the silicon oxide is 1 wt % to 20 wt % based on a total weight of the silicon-carbon composite.

4. The negative active material of claim 1 , wherein a content of the crystalline carbon is 2 wt % to 10 wt % based on a total weight of the silicon-carbon composite.

5. The negative active material of claim 1 , wherein the crystalline carbon is artificial graphite, natural graphite, or a combination thereof.

6. A method of preparing a negative active material for a lithium secondary battery comprising
mixing crystalline carbon particles having an oxide of crystalline carbon on the surface and silicon particles having an oxide of silicon particles on the surface to prepare a first mixture;
adding an amorphous carbon precursor to the first mixture to prepare a second mixture; and
heat-treating the second mixture.

7. The method of claim 6 , wherein the crystalline carbon particles having the oxide of crystalline carbon on the surface are prepared by heat-treating crystalline carbon particles under a nitrogen atmosphere, an oxygen atmosphere, an air atmosphere, or a combination atmosphere.

8. The method of claim 6 , wherein the silicon particles having the oxide of silicon particles on the surface are prepared by heat-treating silicon particles under a nitrogen atmosphere, an oxygen atmosphere, an air atmosphere, or a combination atmosphere.

9. The method of claim 6 , wherein the mixing is performed at 70° C. to 90° C.

10. The method of claim 6 , wherein a mixing ratio of the crystalline carbon particles having the oxide of crystalline carbon on the surface and the silicon particles having the oxide of silicon particles on the surface is 10: 90 wt % to 90: 10 wt %.

11. The method of claim 6 , wherein a mixing ratio of the first mixture and the amorphous carbon precursor is 5:95 wt % to 30:70 wt %.

12. A lithium secondary battery, comprising
a negative electrode comprising the negative active material of claim 1 ;
a positive electrode including a positive active material; and
an electrolyte.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Park Sangeun
• Kwak Jiyeon
• Kim Yeongap
• Kim Youngugk
• Do Uisong
• Oh Yuntaek
• You Yongchan
• Jeong Changui
• Cha Inoh
• Choi Hee Seon

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• C04B2235/425

  Graphite · CPC title

• C04B35/532

  containing a carbonisable binder · CPC title

• H01M4/364 Primary

  as mixtures · CPC title

• C04B2235/5445

  submicron sized, i.e. from 0,1 to 1 micron · CPC title