Methods for forming negative electrode active materials for lithium-based batteries

Patent metadata

Field	Value
Publication number	US-9379374-B2
Application number	US-201414332184-A
Country	US
Kind code	B2
Filing date	Jul 15, 2014
Priority date	Jul 15, 2014
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

In an example method, a transition metal precursor is selected so its transition metal has a diffusion rate that is slower than a diffusion rate of silicon. An aqueous mixture is formed by dissolving the precursor in an aqueous medium, and adding silicon particles to the medium. The mixture is exposed to a hydroxide, which forms a product including the silicon particles and a transition metal hydroxide precipitate. The product is dried. In an inert or reducing environment, silicon atoms of the silicon particles in the dried product are caused to diffuse out of, and form voids in and/or at a surface of, the particles. At least some silicon atoms react with the transition metal hydroxide in the dried product to form i) a SiO x (0<x≦2) coating on the silicon particles and ii) the transition metal, which reacts with other silicon atoms to form silicides.

First claim

What is claimed is:

1. A method for forming a negative electrode active material, the method comprising:
selecting a transition metal precursor including a transition metal having a diffusion rate that is slower than a diffusion rate of silicon;
forming an aqueous mixture by:
dissolving the transition metal precursor in an aqueous medium; and
adding silicon particles to the aqueous medium;
exposing the aqueous mixture to a hydroxide, thereby forming a product including the silicon particles and a transition metal hydroxide precipitate;
drying the product; and
in an inert or reducing environment, causing silicon atoms of the silicon particles in the dried product to diffuse out of the silicon particles, thereby forming voids in the silicon particles, on a surface of the silicon particles, or both in the silicon particles and on the surface of the silicon particles, and whereby at least some of the silicon atoms react with the transition metal hydroxide in the dried product to form i) a SiO x (0<x≦2) coating on the silicon particles and ii) the transition metal, and whereby at least some other of the silicon atoms react with the transition metal to form silicides.

2. The method as defined in claim 1 , further comprising removing the SiO x (0<x≦2) coating from the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

3. The method as defined in claim 1 wherein the transition metal is selected from the group consisting of chromium, and titanium.

4. The method as defined in claim 1 , further comprising forming a carbon coating layer on the SiO x (0<x≦2) coating.

5. The method as defined in claim 4 wherein the carbon coating layer is a substantially amorphous carbon layer and wherein the carbon coating layer is formed using chemical vapor deposition or a polyol method.

6. The method as defined in claim 4 wherein after forming the carbon coating layer, the method further comprises removing the SiO x (0<x≦2) coating, thereby forming a gap between the respective carbon coating layers and each of the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

7. The method as defined in claim 1 , further comprising any of:
i) removing the SiO x (0<x≦2) coating from the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof; or
ii) forming a carbon coating layer on the SiO x (0<x≦2) coating to form multi-layered silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof; or
iii) forming a carbon coating layer on the SiO x (0<x≦2) coating; and
then removing the SiO x (0<x≦2) coating to form carbon-coated silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

8. The method as defined in claim 7 , further comprising incorporating the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof, or the multi-layered silicon particles, or the carbon-coated silicon particles into a negative electrode of a battery.

9. The method as defined in claim 8 wherein the battery is a lithium ion battery or lithium-sulfur battery.

10. A method for forming a negative electrode active material, the method comprising: selecting a transition metal precursor including a transition metal having a diffusion rate that is faster than a diffusion rate of silicon;
forming an aqueous mixture by:
dissolving the transition metal precursor in an aqueous medium; and
adding silicon particles to the aqueous medium;
exposing the aqueous mixture to a hydroxide, thereby forming a product including the silicon particles and a transition metal hydroxide precipitate;
drying the product; and
in an inert or reducing environment, causing transition metal atoms of the transition metal hydroxide in the dried product to diffuse into the silicon particles, thereby forming silicides in the silicon particles, on a surface of the silicon particles, or both in the silicon particles and on the surface of the silicon particles, and whereby hydroxide ions of the transition metal hydroxide react with silicon atoms at a surface of the silicon particles to form a SiO x (0<x≦2) coating on the silicon particles; and

removing the silicides to form voids in the silicon particles, at the surface of the silicon particles, or both in the silicon particles and on the surface of the silicon particles.

11. The method as defined in claim 10 , further comprising removing the SiO x (0<x≦2) coating from the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

12. The method as defined in claim 10 wherein the transition metal is selected from the group consisting of iron, cobalt, nickel, copper, and vanadium.

13. The method as defined in claim 10 , further comprising forming a carbon coating layer on the SiO x (0<x≦2) coating.

14. The method as defined in claim 13 , wherein the carbon coating layer is a substantially amorphous carbon layer and wherein the carbon coating layer is formed using chemical vapor deposition or a polyol method.

15. The method as defined in claim 13 wherein the carbon coating layer is formed prior to removing the silicides, and wherein after the carbon coating layer is formed, the method further comprises removing the SiO x (0<x≦2) coating simultaneously with the removing of the silicides, thereby forming a gap between the respective carbon coating layers and each of the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

16. The method as defined in claim 10 , further comprising any of:
i) removing the SiO x (0<x≦2) coating simultaneously with the removing of the silicides, thereby forming the silicon particles having the voids therein, on the surface thereof, or both therein and on the surface thereof; or
ii) forming a carbon coating layer on the SiO x (0<x≦2) coating prior to removing the silicides; and
then removing the SiO x (0<x≦2) coating simultaneously with the removing of the silicides, thereby forming carbon-coated silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof.

17. The method as defined in claim 16 , further comprising incorporating the silicon particles having the voids formed therein, on the surface thereof, or both therein and on the surface thereof or the carbon-coated silicon particles having the voids formed therein on the surface thereof, or both therein and on the surface thereof into a negative electrode of a battery.

18. The method as defined in claim 17 , wherein the battery is a lithium ion battery or lithium-sulfur battery.

19. The method as defined in claim 10 wherein removing the silicides is accomplished via oxidation and leaching.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Liu Zhongyi
• Xiao Xingcheng
• Carpenter Michael K

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M4/366

  as layered products · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M4/583

  Carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title