Electrochemical double layer capacitor having carbon powder electrodes

• US 20020093783A1
• Filed: 11/01/2001
• Published: 07/18/2002
• Est. Priority Date: 05/12/2000
• Status: Active Grant

• Current Assignee: UCAP Power, Inc.
• Original Assignee: Maxwell Technologies Incorporated (Tesla Inc.)
• Inventors: Nanjundiah, Chenniah, Dispennette, John M., Bendale, Priya, Malay, Manuel R., Chaney, Earl
• Granted Patent: US 6,631,074 B2
• Time in Patent Office: Days
• US Class Current: 361/502
• CPC Class Codes: H01G 11/28 arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
• CPC Class Codes: H01G 11/38 Carbon pastes or blends; Binders or additives therein
• CPC Class Codes: H01G 11/42 Powders or particles, e.g. composition thereof
• CPC Class Codes: H01G 11/86 specially adapted for electrodes carbonisation or activation of carbon for the manufacture of electrodes H01G11/34
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

A method of making an electrode structure, an electrode structure, and a double layer capacitor including the electrode structure, the method includes the steps of: applying a first slurry including conducting carbon powder and a binder to a current collector plate; curing the applied first slurry to form a primary coating; applying a second slurry that includes activated carbon powder, a solvent and a binder to the primary coating; and curing the applied second slurry to form a secondary coating, thereby forming a first electrode. In variations, additional primary and secondary coatings may be formed on both sides of the collector plate.

Claims

1. A method of making an electrode structure for use in a double layer capacitor, comprising the steps of:

applying a first slurry including conducting carbon powder and a binder to a current collector plate;

curing the applied first slurry to form a primary coating;

applying a second slurry that includes activated carbon powder, a solvent and a binder to the primary coating; and

curing the applied second slurry to form a secondary coating, thereby forming a first electrode.

2. The method of claim 1 wherein the proportion of the conducting carbon powder in the first slurry is about 25% to about 90% of the first slurry.

3. The method of claim 1 wherein the proportion of the activated carbon powder in the second slurry is about 5% to about 40% of the second slurry by weight.

4. The method of claim 1 wherein a surface area of the activated carbon powder is between 500 and 2500 m²/g.

5. The method of claim 1 wherein a particle size distribution of the activated carbon powder is between 3 and 30 μ

m.

6. The method of claim 1 wherein a pore size of the activated carbon powder is between 60 and 500 nm.

7. The method of claim 1 wherein a capacitance of the first electrode is between 22 and 35 F/g.

8. The method of claim 1 wherein the first slurry is free of activated carbon.

9. The method of claim 1 wherein the second slurry further comprises conducting carbon powder.

10. The method of claim 9 wherein the conducting carbon powder in the second slurry is about 0.01% to about 5% of the second slurry.

11. The method of claim 1 further comprising removing a portion of the applied first slurry prior to curing the applied first slurry to form a contact portion of the current collector plate.

12. The method of claim 1 further comprising treating, prior to the applying the first slurry step, the current collector plate to promote wettability and adhesion with the first slurry.

14. The double layer capacitor of claim 10 further comprising:

a first capacitor terminal; and

a second capacitor terminal;

wherein a portion of the first current collector foil is coupled to the first capacitor terminal and a portion of the second current collector foil is coupled to the second capacitor terminal.

16. The method of claim 15 further comprising:

removing a portion of the applied first slurry prior to the curing the applied first slurry step to form the first primary coating; and

removing a portion of the applied first slurry of the other side of the current collector plate prior to the curing the applied first slurry step to form the second primary coating.

18. The structure of claim 17 wherein the current collector foil includes a length, a width and a thickness, wherein the primary coating covers an area one each side of the current collector foil across the entire length and across a portion of the width, wherein a contact portion is the portion of the current collector foil not covered by the primary coatings.

20. The capacitor of claim 19 wherein the first and second secondary coatings further comprise conducting carbon powder.

13. A double layer capacitor comprising:

a first electrode structure that includes a first current collector foil, a first primary coating formed on a portion of the first current collector foil, and a first secondary coating formed on the first primary coating;

a second electrode structure that includes a second current collector foil, a second primary coating formed on a portion of the second current collector foil, and a second secondary coating formed on the second primary coating, wherein the first and second primary coatings include conducting carbon powder and the first and second secondary coatings include activated carbon powder;

a porous separator positioned between the first and second electrodes structures such that the porous separator contacts and separates the first and second secondary coatings; and

means for saturating the porous separator and the first and second electrodes structures in a prescribed electrolyte solution.

15. A method of making an electrode structure for use in a double layer capacitor, comprising the steps of:

applying a first slurry including conducting carbon powder and a binder to one side of a current collector plate;

curing the applied first slurry to form a first primary coating;

applying a second slurry that includes activated carbon powder, a solvent and a binder to the first primary coating;

curing the applied second slurry to form a first secondary coating;

applying the first slurry to another side of the current collector plate that is opposite of the one side of the current collector plate;

curing the applied first slurry to form a second primary coating on the other side of the current collector plate;

applying the second slurry to the second primary coating;

curing the applied second slurry to form a second secondary coating on the second primary coating, thereby forming a first electrode.

17. An electrode structure for use in a double layer capacitor comprising:

a current collector foil;

a primary coating formed on each of a first side and a second side of the current collector foil, each primary coating including conducting carbon and a binder; and

a secondary coating formed on each of the primary coatings, each secondary coating including activated carbon powder, a solvent and a binder.

19. A double layer capacitor comprising:

a first electrode structure that includes a first current collector foil, a first primary coating formed on each side of the first current collector foil, and a first secondary coating formed on each of the first primary coatings;

a second electrode structure that includes a second current collector foil, a second primary coating formed on each side of the second current collector foil, and a second secondary coating formed on each of the second primary coatings, wherein the first and second primary coatings include conducting carbon powder and the first and second secondary coatings include activated carbon powder;

a porous separator positioned between the first and second electrodes structures such that the porous separator contacts and electrically separates the first and second secondary coatings of the first and second electrode structures facing each other; and

means for saturating the porous separator and the first and second electrodes structures in a prescribed electrolyte solution.