SILICON BASED COMPOSITE MATERIAL

• US 20090179181A1
• Filed: 01/08/2009
• Published: 07/16/2009
• Est. Priority Date: 01/11/2008
• Status: Active Grant

• Current Assignee: A123 Systems Incorporated
• Original Assignee: A123 Systems Incorporated
• Inventors: Chin, Jun Q., Wang, Liya, Zhang, Pu, Mani, Suresh, Ma, Junqing
• Granted Patent: US 8,679,679 B2
• Time in Patent Office: Days
• US Class Current: 252/503
• CPC Class Codes: H01B 1/16 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/18 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

A composite material having utility as an anode for lithium ion batteries comprises silicon, a transition metal, a ceramic and an electrically conductive diluent such as carbon. In particular instances, the ceramic is electrically conductive, and may comprise vanadium carbide or tungsten carbide. The transition metal may, in some instances, comprise iron. The material may be fabricated by grinding together a starting mixture of the components, and grinding may be accomplished in a high impact ball milling process, and the grinding step may cause partial alloying of the silicon with the metal and/or carbon. Further disclosed is a method for making the material as well as electrodes which incorporate the material.

Claims

1. A composite material having utility in an electrode for an electrochemical device, said material comprising:

silicon;

a transition metal;

a ceramic; and

an electrically conductive diluent.

2. The material of claim 1, comprising, on a weight basis, 5-85% silicon, 1-50% of said transition metal, 1-50% of said ceramic, and 1-80% of said diluent.

3. The material of claim 1, wherein said transition metal comprises iron, cobalt, nickel, copper, manganese, chromium or vanadium.

4. The material of claim 1, wherein said ceramic is a material selected from the group consisting of nitrides, carbides, oxides, oxynitrides, oxycarbides, and combinations thereof.

5. The material of claim 1, wherein said ceramic is electrically conductive.

6. The material of claim 4, wherein said ceramic is vanadium carbide.

7. The material of claim 4, wherein said ceramic is tungsten carbide.

8. The material of claim 1, wherein said diluent comprises carbon.

9. The material of claim 1, wherein said diluent comprises mesocarbon microbeads.

10. The material of claim 1, wherein said silicon and said transition metal are present in an approximately equal weight basis.

11. The material of claim 1, wherein said silicon and said transition metal are at least partially alloyed.

12. The material of claim 1, wherein said transition metal component comprises at least two different transition metals.

13. The material of claim 1, wherein said material has a particle size in the range of 10 nanometers-50 micrometers.

24. An electrode which includes the composite material of claim 1.

14. A composite material comprising, on a weight basis, 20% silicon, 20% iron, 10% vanadium carbide, and the remainder, carbon.

15. A composite material comprising, on a weight basis, 20% silicon, 20% iron, 10% tungsten carbide, and the remainder, carbon.

16. A method for making a composite material, said method comprising the steps of:

providing a starting mixture comprising, by weight;

5-85% silicon;

1-50% of a transition metal;

1-50% of a ceramic;

1-80% of carbon; and

grinding said starting mixture.

17. The method of claim 16, wherein the step of grinding said mixture comprises ball milling said mixture.

18. The method of claim 16, wherein the step of grinding said mixture comprises grinding said mixture in a high impact ball milling process.

19. The method of claim 16, wherein the step of grinding said mixture comprises grinding said mixture in an attrition ball milling process.

20. The method of claim 16, wherein said transition metal comprises iron.

21. The method of claim 16, wherein said ceramic comprises VC.

22. The method of claim 16, wherein said ceramic comprises WC.

23. The method of claim 16, wherein said starting mixture further includes tin.