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

• US 8,101,298 B2
• Filed: 01/23/2007
• Issued: 01/24/2012
• Est. Priority Date: 01/23/2006
• Status: Active Grant

• Current Assignee: Nexeon Limited
• Original Assignee: Nexeon Limited
• Inventors: Green, Mino, Liu, Feng-Ming
• Primary Examiner(s): Conley, Helen O
• Application Number:
  US12/161,126
• Publication Number:
  US 20100151324A1
• Time in Patent Office: 1,827 Days
• Field of Search: 429/218.1, 429/209, 502/101
• US Class Current: 429/218.1
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: C30B 29/60 characterised by shape
• CPC Class Codes: C30B 33/08 Etching
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/0402 Methods of deposition of the material
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1393 of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• 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: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• 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 29/49108 Electric battery cell making
• CPC Class Codes: Y10T 29/49115 including coating or impregnating

Abstract

A method of fabricating fibres of silicon or silicon-based material comprises the steps of etching pillars on a substrate and detaching them. A battery anode can then be created by using the fibres as the active material in a composite anode electrode.

Claims

1. A method of creating a cell electrode for an electrochemical cell, the method comprising:

etching a silicon or silicon-based substrate to form fibres;

detaching the fibres from the substrate;

depositing a slurry containing a plurality of the fibres to form a layer of fibres;

wherein at least some of the fibres cross over to provide intersections.

2. A method of creating a cell electrode for a battery, the method comprising:

etching a silicon or silicon-based substrate, comprising n-type or p-type silicon, to form fibres;

detaching the fibres from the substrate; and

forming a layer of fibres in which the fibres cross over each other to provide multiple intersections.

3. A method as claimed in claim 2 in which the fibres have transverse dimensions in the range 0.08 to 0.5 microns.

4. A method as claimed in claim 3 wherein the fibres have a length in the range of 20 to 300 microns.

5. A method as claimed in claim 2 in which the fibres have an aspect ratio greater than 40:

1.

6. A method as claimed in claim 2 in which the fibres have a substantially non-circular cross-section.

7. A method as claimed in claim 2 in which the pillars are created by reactive ion etching.

8. A method as claimed in claim 2 in which the pillars are created by chemical reaction etching.

9. A method as claimed in claim 8 in which the pillars are created by galvanic exchange etching.

10. A method as claimed in claim 2 in which the pillars are detached by one or more of scraping, agitating or chemical etching.

11. A method as claimed in claim 2 in which the silicon or silicon-based material comprises one of undoped silicon, doped silicon, or a silicon germanium mixture.

12. A method of creating a cell electrode comprising depositing a slurry containing silicon-based fibres to form a layer of silicon-based fibres, wherein the fibres are formed by the method of claim 2.

13. A method as claimed in claim 12 in which the fibres are deposited in a felt.

14. A method as claimed in claim 12 in which the electrode is a composite electrode comprising at least one of a binder and a conductive additive.

15. The method as claimed in claim 14 wherein the composite electrode has a percentage pore volume of about 10-30 percent.

16. A method as claimed in claim 12 including depositing the fibres on a current collector.

17. A method of fabricating a lithium rechargeable cell comprising the steps of creating an anode as claimed in claim 12 arranging the electrode as an anode and adding a cathode and an electrolyte.

18. A method of fabricating an electrode for an electrochemical cell, the method comprising the steps of:

etching a silicon substrate or a silicon-based substrate to make pillars;

detaching pillars from the substrate to give electrode fibres of silicon or a silicon-based material; and

forming an electrically interconnected mass of electrode fibres, wherein the electrode fibres form an electrochemically active material of the electrode, and the fibres comprise n-type or p-type silicon.

19. A method as claimed in claim 18 in which a mass of silicon in the electrically interconnected mass is 70 to 95 percent.

20. A method as claimed in claim 18 in which the electrically-interconnected mass has a percentage pore volume of about 10-30 percent.