Fuel cell electrode

• US 20050074663A1
• Filed: 09/01/2004
• Published: 04/07/2005
• Est. Priority Date: 10/03/2003
• Status: Active Grant

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Harmer, Mark Andrew, Damore, Michael B., Farneth, William E.
• Granted Patent: US 7,615,293 B2
• Time in Patent Office: Days
• US Class Current: 429/401
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01M 2250/30 Fuel cells in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8647 consisting of more than one material, e.g. consisting of composites
• CPC Class Codes: H01M 4/8673 Electrically conductive fillers
• CPC Class Codes: H01M 4/8807 Gas diffusion layers
• CPC Class Codes: H01M 4/8814 Temporary supports, e.g. decal
• CPC Class Codes: H01M 4/8828 Coating with slurry or ink
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: H01M 8/0247 characterised by the form characterised by a channel configuration H01M8/0258
• CPC Class Codes: H01M 8/1009 with one of the reactants being liquid, solid or liquid-charged H01M8/12 takes precedence
• CPC Class Codes: H01M 8/16 Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

Abstract

The invention is directed to an electrode, suitable for use in a fuel cell, consisting of a microporous current collector incorporating a multitude of domains and wherein each domain contains soluble redox catalyst.

Claims

1. A fuel cell electrode comprising a porous current collector in contact with a multitude of domains, each domain containing:

a) a redox catalyst; and

b) an electron transport mediator;

wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain.

2. A fuel cell electrode according to claim 1 wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material.

3. A fuel cell electrode according to claim 1 wherein the redox catalyst and the electron transport mediator are bounded in the domain by a first porous current collector and the juxtaposition of a second current collector.

4. A fuel cell electrode according to claim 2 wherein the containment material is selected from the group consisting of:

polyelectrolyte polymers, porous metal oxide-based coatings, organically modified metal oxides and fluorine-containing polymers.

5. A fuel cell electrode according to claim 2 wherein the containment material is a film.

6. A fuel cell electrode according to claim 5 wherein the film is comprised of materials selected from the group consisting of:

silica, titania, alumina, polyesters, polyamides, polyimides, fluoropolymers, polyelectrolytes, organo-substituted silica, silicones, tetraalkoxysilanes, organoalkoxy silanes, alkoxytitanates, diamines and diacids.

7. A fuel cell electrode according to claim 6 wherein the containment material is silica or a colloidal carbon emulsion.

8. A fuel cell electrode according to claim 1 wherein the porous current collector comprises an electrical conducting material.

9. A fuel cell electrode according to claim 8 wherein the electrical conducting material is selected from the group consisting of:

carbon paper, carbon paste, carbon nanotubes, carbon particles, conducting polymers, noble metal particles and conducting metal oxide particles.

10. A fuel cell electrode according to claim 1 wherein the diameter of the domain is less than 100 μ

m.

11. A fuel cell electrode according to claim 1 wherein the diameter of the domain is less than 10 μ

m.

12. A fuel cell electrode according to claim 1 wherein the redox catalyst is an enzyme.

13. A fuel cell electrode according to claim 12 wherein the enzyme is an oxido-reductase.

14. A fuel cell electrode according to claim 13 wherein the electrode is a cathode and the oxido-reductase is laccase.

15. A fuel cell electrode according to claim 1 wherein the electrode is a cathode and the electron transport mediator has a redox potential that is less than 0.3 V positive of the redox potential of the catalyst.

16. A fuel cell electrode according to claim 1 wherein the electrode is a cathode and the electron transport mediator has a redox potential that is less than 0.1 V positive of the redox potential of the catalyst.

17. A fuel cell electrode according to claim 1 wherein the electrode is an anode and the electron transport mediator has a redox potential that is less than 0.3 V negative of the redox potential of the catalyst.

18. A fuel cell electrode according to claim 1 wherein the electrode is an anode and the electron transport mediator has a redox potential that is less than 0.1 V negative of the redox potential of the catalyst.

19. A fuel cell electrode according to claim 1 wherein the electron transport mediator is selected from the group consisting of:

quinones, hydroquinones, metalloorganic complexes, conjugated unsaturated acyclic and cyclic molecules, metal ions and biological electron carriers.

20. A fuel cell electrode according to claim 1 wherein the electrode is a cathode and the electron transport mediator is 2,2′

-azinobis(3-ethylbenzothiazoline-6-sulfonate).

21. An electrode according to claim 1, wherein said electrode produces in excess of 50 mA per cm² of projected electrode surface area.

22. An electrode according to claim 21 having the following parameters:

a) a microdomain with about 4×

10<sup>−

9</sup> moles of a redox catalyst;

b) an electron transport mediator in a concentration of about 5×

10<sup>−

3</sup>M;

c) an effective volumetric surface area of the microporous current collector in excess of 100 cm²;

wherein all of the redox catalyst resides within about 3 μ

m of the current collector surface, and all of the current collector surface resides within 10 μ

m of a reservoir of air-saturated aqueous buffer.

23. A fuel cell comprising the electrode of claim 1.

24. A fuel cell of claim 23 wherein the electrode is an anode.

25. A fuel cell of claim 23 wherein the electrode is a cathode.

28. A portable electronic device comprising a fuel cell of any of claims 23-27.

26. A fuel cell comprising:

(i) an anode configured and arranged for electro-oxidizing an anode reductant; and

(ii) a cathode spaced apart from the anode and configured and arranged for electro-reducing a cathode oxidant, the cathode comprising a porous current collector comprising an electrical conducting material, in contact with a multitude of domains, each domain containing;

a) a redox catalyst; and

b) an electron transport mediator;

wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain and wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material; and

wherein the diameter of the domain is less than 100 μ

m.

27. A fuel cell comprising:

(i) a cathode configured and arranged for electro-reducing a cathode oxidant; and

(ii) an anode spaced apart from the cathode and configured and arranged for electro-oxidizing an anode reductant, the anode comprising a porous current collector comprising an electrical conducting material, in contact with a multitude of domains, each domain containing;

a) a redox catalyst; and

b) an electron transport mediator;

wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain and wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material; and

wherein the diameter of the domain is less than 100 μ

m.