STRUCTURED SILICON ANODE

• US 20090130563A1
• Filed: 12/12/2008
• Published: 05/21/2009
• Est. Priority Date: 11/05/2002
• Status: Active Grant

• Current Assignee: Nexeon Limited
• Original Assignee: Nexeon Limited
• Inventors: Green, Mino
• Granted Patent: US 7,683,359 B2
• Time in Patent Office: Days
• US Class Current: 429/231.950
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/04 Processes of manufacture in general
• 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: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 438/90 Bulk effect device making
• CPC Class Codes: Y10S 977/701 Integrated with dissimilar structures on a common substrate
• CPC Class Codes: Y10S 977/81 Of specified metal or metal alloy composition
• CPC Class Codes: Y10S 977/932 for electronic or optoelectronic application
• CPC Class Codes: Y10S 977/948 Energy storage/generating using nanostructure, e.g. fuel cell, battery
• CPC Class Codes: Y10T 29/49108 Electric battery cell making

Abstract

A silicon/lithium battery can be fabricated from a substrate. This allows the battery to be produced as an integrated unit on a chip. The battery includes an anode formed from an array of submicron structures including silicon fabricated on a substrate and a cathode including lithium.

Claims

1-8. -8. (canceled)

9. An energy storage device comprising:

an anode comprising an array of sub-micron structures comprising silicon, on a substrate; and

a cathode comprising lithium, arranged to form a battery.

10. A device according to claim 9 wherein the substrate comprises silicon.

11. A device according to claim 9 wherein the anode is arranged to tolerate the conditions occasioned by the volume changes caused by charging/discharging of the battery.

12. A device according to claim 9 wherein the anode is arranged to maintain structural integrity throughout a cycling of the battery.

13. A device according to claim 9 wherein the anode is arranged to withstand repeated volume expansion associated with alloying during use of the battery.

14. A device according to claim 9 wherein the array of sub-micron structures comprise an array of sub-micron pillars.

15. A device according to claim 14 wherein the pillars have a surface area of about 4 FH/d times the substrate area wherein F is the surface fractional coverage, H is the height of the pillar and d is the diameter of the pillar.

16. A device according to claim 14 in which the sub-micron pillars do not exceed a fractional coverage of 0.5 of the substrate.

17. A device according to claim 14 wherein the pillars are 0.1 to 1.0 microns in diameter and 1 to 10 microns in height.

18. A device according to claim 14 wherein the pillars are approximately 0.3 microns in diameter and 6 microns in height.

19. A device according to claim 9 in which the substrate comprises n-type silicon.

20. A device according to claim 9 made on a wafer-bonded silicon-on-insulator substrate.

21. A method of forming the anode according to claim 9, the method comprising:

(a) depositing a film of a soluble solid onto a hydrophilic silicon substrate;

(b) exposing the film to solvent vapour so that the film reorganises into an array of discrete hemispherical islands on the surface; and

(c) reactively ion etching the silicon substrate with the islands of highly soluble solid acting as a resist so that the exposed silicon is etched away leaving pillars corresponding to the islands.

22. A battery including an anode comprising:

an array of sub-micron pillars comprising silicon fabricated on a substrate; and

a lithium cathode, wherein a compound film is formed on the pillars in a charging step.

23. A battery according to claim 22 wherein the film is a Zintl-Phase Compound.

24. A battery according to claim 22 wherein the compound film is deformable so as not to give rise to significant stress-induced cracking during the volume change in a charging or discharging step.

25. The battery according to claim 22 wherein the substrate comprises silicon.

26. An electrode for a battery comprising sub-micron pillars comprises silicon supported on a substrate and arranged to form a battery with a lithium cathode and a lithium-based electrolyte.

27. The electrode according to claim 26 wherein the substrate comprises silicon.