Multi-electrode double layer capacitor having single electrolyte seal and aluminum-impregnated carbon cloth electrodes

• US 6,233,135 B1
• Filed: 08/18/1999
• Issued: 05/15/2001
• Est. Priority Date: 10/07/1994
• Status: Expired due to Fees

• Current Assignee: Tesla Inc.
• Original Assignee: Maxwell Energy Products Incorporated
• Inventors: Crawford, Robert W., Dispennette, John M., Blank, Edward, Farahmandi, C. Joseph
• Primary Examiner(s): Dinkins, Anthony
• Application Number:
  US09/377,327
• Time in Patent Office: 636 Days
• Field of Search: 361/502-505, 361/508-509, 361/516-517, 361/512, 361/523, 361/525, 361/528-529, 361/532-533, 29/250.3, 252/62.2, 429/34, 429/46, 429/128-129
• US Class Current: 361/502
• CPC Class Codes: H01G 11/12 Stacked hybrid or EDL capacitors
• CPC Class Codes: H01G 11/52 Separators
• CPC Class Codes: H01G 11/72 specially adapted for integration in multiple or stacked hybrid or EDL capacitors
• CPC Class Codes: H01G 11/78 Cases; Housings; Encapsulations; Mountings
• CPC Class Codes: H01G 11/82 Fixing or assembling a capacitive element in a housing, e.g. mounting electrodes, current collectors or terminals in containers or encapsulations
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 29/49149 by metal fusion bonding

Abstract

A single cell, multi-electrode high performance double layer capacitor includes an electrode stack adapted to fit within a capacitor container. The electrode stack comprises a plurality of electrodes, each comprising a current collector foil and a carbon cloth impregnated with a specified metal in direct physical contact with the current collector foil. The current collector foils of alternating electrodes are coupled to the first capacitor terminal, and the current collector foils of other alternating electrodes are coupled to the second capacitor terminal. A porous separator material is positioned between each electrode of the electrode stack, and has pores therein through which ions may readily pass while preventing adjacent electrodes from electrically contacting each other. The capacitor case comprises a first part and a second part fastenable to each other to form a sealed capacitor case which has a first capacitor terminal and a second capacitor terminal associated therewith. The electrode stack is maintained under a constant modest pressure within the sealed capacitor case and a prescribed electrolytic solution is sealed within the sealed capacitor case, whereby the electrode stack is saturated and immersed within the electrolytic solution. In one embodiment, the porous separator material comprises a contiguous porous separator sheet that winds throughout the electrode stack in a serpentine manner.

Claims

1. A double layer capacitor comprising:

a capacitor case comprising a first part and a second part fastenable to each other to form a sealed capacitor case, the sealed capacitor case having a first capacitor terminal and a second capacitor terminal associated therewith;

an electrode stack comprising a plurality of electrodes, each electrode of the electrode stack comprising a current collector foil and a carbon cloth impregnated with a specified metal in direct physical contact with the current collector foil, and wherein current collector foils of alternating electrodes are coupled to the first capacitor terminal, and the wherein the current collector foils of other alternating electrodes are coupled to the second capacitor terminal;

a porous separator material positioned between each electrode of the electrode stack, the porous separator material having pores therein through which ions may readily pass, wherein adjacent electrodes are prevented from electrically contacting each other by the porous separator material;

the electrode stack being maintained under a constant modest pressure within the sealed capacitor case; and

a prescribed electrolytic solution sealed within the sealed capacitor case, whereby the electrode stack is saturated and immersed within the electrolytic solution.

2. The double layer capacitor of claim 1 wherein said porous separator material comprises a contiguous sheet of said porous separator material, the contiguous sheet folded between said each electrode of said electrode stack in a serpentine fashion and wrapped around said electrode stack forming a wrapped electrode stack.

3. The double layer capacitor of claim 2 further comprising a shim placed in between said wrapped electrode stack and an interior of said sealed capacitor case, wherein the shim has a thickness sufficient to exert a modest constant pressure against said wrapped electrode stack.

4. The double layer capacitor of claim 3 further comprising a corner protector placed in between said shim and said interior of said sealed capacitor case.

5. The double layer capacitor of claim 1 wherein said current collector foil of each of said plurality of electrodes comprises a paddle portion and a tab portion, said carbon cloth impregnated with said specified metal in direct physical contact with the paddle portion of said current collector foil, each tab portion of said plurality of current collector foils is coupled to the said first or second capacitor terminal.

6. The double layer capacitor of claim 5 wherein said current collector foil of each of said plurality of electrodes further comprises said tab portion positioned offset from a central axis of said paddle portion.

7. The double layer capacitor of claim 5 wherein said current collector foil of each of said plurality of electrodes further comprises said tab portion positioned flush with an edge of said paddle portion.

8. The double layer capacitor of claim 5 wherein all tab portions of said plurality of current collector foils generally extend from one end of said electrode stack.

9. The double layer capacitor of claim 1 wherein said first part of said sealed capacitor case comprises a open-ended container for containing said electrode stack.

10. The double layer capacitor of claim 9 wherein said second part of said sealed capacitor case comprises a lid for sealing said open-ended container, the lid having a fill hole, and the lid for receiving said first and second capacitor terminals.

11. The double layer capacitor of claim 1 wherein said sealed capacitor case is insulated from said first and second capacitor terminals.

12. The double layer capacitor of claim 1 wherein said specified metal is selected from a group consisting of aluminum, titanium, and copper.

13. The double layer capacitor of claim 1 wherein said carbon cloth impregnated with said specified metal comprises said carbon cloth made from activated carbon fiber bundles, the spaces between the activated carbon fibers within the activated carbon fiber bundle being referred to as a “

tow”

of the activated carbon fiber bundle, and wherein the activated carbon fiber bundles are woven to form said carbon cloth, and further wherein said specified metal is impregnated into the tow to reduce the transverse resistance of said carbon cloth.

14. The double layer capacitor of claim 13 wherein said activated carbon fiber bundle is an activated triple twisted carbon fiber bundle.

15. The double layer capacitor of claim 13 wherein said activated carbon fiber bundle comprises a triple twisted carbon fiber bundle.

16. A wrapped electrode stack comprising:

a plurality of impregnated carbon cloths, each of the plurality of impregnated carbon cloths having been impregnated with a specified metal;

a plurality of current collector foils, each of the plurality of current collector foils having a tab portion and a paddle portion;

a plurality of electrodes, each of the plurality of electrodes comprising one of the plurality of current collector foils making direct physical contact with one of the plurality of impregnated carbon cloths;

an electrode stack comprising the plurality of electrodes stacked such that alternating tab portions align with each other, forming a first set of aligned tab portions and a second set of aligned tab portions; and

a contiguous porous separator sheet wound throughout the electrode stack in a serpentine manner between each of the plurality of electrodes and wrapped around the electrode stack, wherein the contiguous porous separator sheet acts as an electrical insulator between adjacent electrodes of the plurality of electrodes.

17. The wrapped electrode stack of claim 16 wherein said tab portion of said each of said plurality of current collector foils is offset from a central axis of said paddle portion.

18. The wrapped electrode stack of claim 16 wherein said first and second set of aligned tab portions generally extend from the same end of said electrode stack.

19. A double layer capacitor comprising:

a capacitor case comprising a first part and a second part fastenable to each other to form a sealed capacitor case, the sealed capacitor case having a first capacitor terminal and a second capacitor terminal associated therewith;

a first electrode comprising a first current collector foil and a first carbon cloth impregnated with a specified metal, the first current collector foil having a first tab portion and a first paddle portion, the first carbon cloth making direct physical contact with the first paddle portion, wherein the first tab portion is coupled to a first capacitor terminal;

a second electrode comprising a second current collector foil and a second carbon cloth impregnated with the specified metal, the second current collector foil having a second tab portion and a second paddle portion, the second carbon cloth making direct physical contact with the second paddle portion, wherein the second tab portion is coupled to a second capacitor terminal;

the first electrode and the second electrode placed against each other, wherein a porous separator material separates the first electrode from the second electrode and the porous separator material wraps around the first electrode and the second electrode, wherein the porous separator material acts as an electrical insulator between the first and second electrodes;

the first electrode and the second electrode being compressed against each other with a modest constant pressure within the sealed capacitor case; and

a prescribed electrolytic solution sealed within the sealed capacitor case so as to saturate and immerse the first electrode, the second electrode, and the porous separator material with the prescribed electrolytic solution.

20. The double layer capacitor of claim 19 wherein said porous separator material comprises a contiguous sheet of said porous separator material, the contiguous sheet folded between said first and second electrode in a serpentine fashion and wrapped around said electrode stack forming a wrapped electrode stack.

21. The double layer capacitor of claim 20 further comprising a shim placed in between said wrapped electrode stack and an interior of said sealed capacitor case, wherein the shim has a thickness sufficient to exert a modest constant pressure against said wrapped electrode stack.

22. The double layer capacitor of claim 19 wherein said first and second tab portions are offset from a central axis of respective said first and second paddle portions.

23. The double layer capacitor of claim 19 wherein said first and second tab portions are flush with an edge of respective said first and second paddle portions.

24. The double layer capacitor of claim 19 wherein said first and second tab portions generally extend from the same end of said first and second electrodes having been stacked, wherein said first and second tab portions do not make contact with each other and are electrically insulated.

25. The double layer capacitor of claim 19 wherein said first part of said sealable capacitor case comprises an open-ended container.

26. The double layer capacitor of claim 25 wherein said second part of said sealed capacitor case comprises a lid for sealing said open-ended container, the lid having a fill hole, and the lid for receiving said first and second capacitor terminals.

27. The double layer capacitor of claim 19 wherein said sealed capacitor case is insulated from said first and second capacitor terminals.

28. The double layer capacitor of claim 19 wherein said specified metal is selected from a group consisting of aluminum, titanium, and copper.

29. The double layer capacitor of claim 19 wherein said carbon cloth impregnated with said specified metal comprises said carbon cloth made from activated carbon fiber bundles, the spaces between the activated carbon fibers within the activated carbon fiber bundle being referred to as a “

tow”

of the activated carbon fiber bundle, and wherein the activated carbon fiber bundles are woven to form said carbon cloth, and further wherein said specified metal is impregnated into the tow to reduce the transverse resistance of said carbon cloth.

30. The double layer capacitor of claim 29 wherein said activated carbon fiber bundle comprises a triple twisted carbon fiber bundle.

31. A double layer capacitor comprising:

a wrapped electrode stack having a plurality of electrodes, each of the plurality of electrodes having a current collector foil and a carbon cloth impregnated with a specified metal placed thereagainst, wherein each of the plurality of electrodes is separated by a porous separator material, the porous separator material winding through the wrapped electrode stack in a serpentine manner and wrapping around the plurality of electrodes, the wrapped electrode stack having first and second capacitor terminals;

an open-ended container for containing the wrapped electrode stack, the open-ended container having an interior dimension less than an exterior dimension of the wrapped electrode stack;

one of more shims, respective shims placed in between the wrapped electrode stack and the interior of the open-ended container, the respective shims for applying a modest constant pressure against the wrapped electrode stack within the open-ended container;

an end portion for sealing the open-ended container, the end portion receiving the first and second capacitor terminals; and

a prescribed electrolytic solution within the open-ended container having been sealed so as to saturate and immerse the wrapped electrode stack with the prescribed electrolytic solution.

32. A carbon cloth electrode for use in a capacitor comprising:

a carbon cloth comprising;

a plurality of twisted carbon fiber bundles, wherein the plurality of twisted carbon fiber bundles are woven together, whereby forming the carbon cloth, wherein each of the plurality of twisted carbon fiber bundles comprises a plurality of carbon fiber bundles, wherein each of the plurality of carbon fiber bundles comprises a plurality of carbon fibers, wherein the plurality of carbon fiber bundles are twisted together such that an exterior of each of the plurality of carbon fiber bundles slightly frays, whereby forming respective ones of the plurality of twisted carbon fiber bundles, whereby the transverse resistance of the carbon cloth electrode is reduced.

33. The carbon cloth electrode of claim 32 wherein said carbon cloth further comprises a specified metal impregnated into a tow of said carbon cloth, wherein the spaces between said plurality of carbon fibers within respective ones of said plurality of carbon fiber bundles being referred to as a “

tow”

of said plurality of twisted carbon fiber bundles, and further wherein the specified metal is impregnated to reduce the transverse resistance of said carbon cloth.

34. The carbon cloth electrode of claim 33 wherein each of said plurality of twisted carbon fiber bundles comprises three carbon fiber bundles.

35. The carbon fiber cloth of claim 33 wherein said specified metal is selected from a group consisting of aluminum, copper, and titanium.