Method of fabricating structured particles composed of silicon or a silicon-based material and their use in lithium rechargeable batteries

• US 8,870,975 B2
• Filed: 11/03/2010
• Issued: 10/28/2014
• Est. Priority Date: 07/17/2007
• Status: Expired due to Fees

• Current Assignee: Nexeon Limited
• Original Assignee: Nexeon Limited
• Inventors: Green, Mino, Liu, Feng-Ming
• Primary Examiner(s): Crepeau, Jonathan
• Assistant Examiner(s): Buchanan, Jacob
• Application Number:
  US12/938,835
• Publication Number:
  US 20110067228A1
• Time in Patent Office: 1,455 Days
• Field of Search: 429/209, 429/218.1, 429/231.9, 429/231.95, 296/231, 216 7- 8, 117/87, 117/205
• US Class Current: 29/623.1
• CPC Class Codes: H01M 10/52 Removing gases inside the secondary cell, e.g. by absorption vent plugs or other mechanical arrangements for facilitating escape of gases H01M50/30
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/0492 Chemical attack of the support material
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 117/102 for forming a platelet shape or a small diameter, elongate, generally cylindrical shape [e.g., whisker, fiber, needle, filament]
• CPC Class Codes: Y10T 29/49108 Electric battery cell making
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

Pillared particles of silicon or silicon-comprising material and a method of fabricating the same are disclosed. These particles may be used to create both a composite anode structure with a polymer binder, a conductive additive and a metal foil current collector, and an electrode structure. The structure of the particles overcomes the problems of charge/discharge capacity loss.

Claims

1. A method of fabricating elongate silicon-comprising fibres from a particle wherein the particle comprises silicon and has a particle core and a plurality of silicon-comprising pillars, each directly attached at a first end to a surface of the particle core and extending substantially radially therefrom, the method comprising detaching the pillars from the particle to form the silicon-comprising fibres wherein the fibres are nanofibres.

2. A method as claimed in claim 1 wherein the pillars are detached from the particle by one or more of scraping, agitating or chemical etching.

3. A method as claimed in claim 1 wherein the particle core comprises silicon.

4. A method as claimed in claim 1 wherein the particle has several surfaces oriented at angles in relation to each other.

5. A method as claimed in claim 1 wherein the pillars coat one or more surfaces of the particle.

6. A method as claimed in claim 1 wherein each pillar in the plurality of pillars is spaced from each adjacent pillar by a void.

7. A method as claimed in claim 1 wherein the plurality of silicon-comprising pillars form one of a regular or irregular array.

8. A method as claimed in claim 1 in which the fibres have a first dimension in the range 0.08 to 0.70 microns.

9. A method as claimed in claim 8 in which the fibres have a second dimension in the range 4 to 100 microns.

10. A method as claimed in claim 1 in which the fibres have an aspect ratio of greater than 20:

1.

11. A method as claimed in claim 1 in which the fibres have a substantially circular or non-circular cross-section.

12. A method as claimed in claim 1 which the particle and/or fibres comprise undoped silicon, doped silicon, n-type silicon, p-type silicon, metallurgical grade silicon or a silicon germanium mixture.

13. A method as claimed in claim 1 wherein the silicon content has a silicon purity of 90.00 to 99.95% by mass.

14. A method as claimed in claim 1 wherein the particle has a regular or irregular cross-section.

15. A method as claimed in claim 1 wherein the particle has a first dimension of 10 μ

m to 1 mm.

16. A method as claimed in claim 1 wherein the particle core or pillars are crystalline or polycrystalline.

17. A method as claimed in claim 1 wherein the fraction of the surface area of the particle core occupied by pillars is 0.10 to 0.50.

18. A method as claimed in claim 1 further comprising the step of fabricating the particle comprising the steps of etching a particle comprising silicon.

19. A method as claimed in claim 18 in which the pillars are created by chemical reaction etching or galvanic exchange etching.

20. A method of fabricating an electrode containing fibres made by the method of claim 1 as one of its active materials.

21. A method as claimed in claim 20 which uses copper as a current collector.

22. A method as claimed in claim 20 in which the electrode is an anode.

23. A method of fabricating an electrochemical cell containing an electrode made by the method of claim 20.

24. A method as claimed in claim 23 further comprising a cathode, in which the cathode comprises a lithium-containing compound capable of releasing and reabsorbing lithium ions as its active material.

25. A method as claimed in claim 24 in which the cathode comprises lithium-based metal oxide, sulphide or phosphate as its active material.

26. A method of fabricating a device powered by a cell made by the method of claim 23.

27. A method of fabricating a lithium rechargeable cell anode comprising fibres made by the method of claim 1 as one of its active materials.

28. A method as claimed in claim 27 in which the fibres are part of a composite film.

29. A method of fabricating a cell comprising an anode made by the method of claim 27 and a cathode.

30. A method as claimed in claim 29 in which the cathode comprises lithium-based material.

31. A method as claimed in claim 30 in which the cathode comprises lithium cobalt dioxide.

32. A method of creating a composite electrode comprising the steps of preparing a solvent-based slurry containing fibres made by the method of claim 1, coating the slurry onto a current collector and evaporating the solvent to create a composite film.

33. A method of fabricating a lithium rechargeable cell comprising the steps of creating an anode made by the method of claim 27 and adding a cathode and an electrolyte.

34. A method as claimed in claim 33 further comprising adding a separator between the cathode and the anode.

35. A method of fabricating a cell electrode comprising depositing a slurry, containing silicon-comprising fibres made by the method of claim 1, to form a layer of silicon-comprising fibres forming the active material of the electrode.

36. A method of fabricating elongate silicon comprising fibres from a particle wherein the particle comprises silicon, and has a particle core and an array of silicon-comprising pillars, each directly attached at a first end to the particle core and extending therefrom, the method comprising detaching the pillars from the particle to form the elongate silicon-comprising fibres, wherein the particle, including the particle core and the silicon-comprising pillars, has a diameter of 0.5 to 100 microns.

37. A method of fabricating elongate silicon-comprising fibres from a particle comprising:

simultaneously etching a plurality of particles wherein each particle comprises silicon and after etching each has a particle core and a plurality of silicon-comprising elongated structures, each attached at a first end to a surface of the particle core and extending outwardly therefrom; and

,

detaching the elongated structures from the at least some of the plurality of particles to form the elongate silicon-comprising fibres wherein the fibres are nanofibres.