Cathode belt structure for use in a metal-air fuel cell battery system and method of fabricating the same

• US 6,365,292 B1
• Filed: 08/10/1998
• Issued: 04/02/2002
• Est. Priority Date: 10/06/1997
• Status: Expired due to Fees

• Current Assignee: Reveo, Inc.
• Original Assignee: Reveo, Inc.
• Inventors: Faris, Sadeg M., Yao, Wayne, Tsai, Tsepin, Chen, Muguo, Legbandt, Thomas J.
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/232,326
• Time in Patent Office: 1,331 Days
• Field of Search: 429/27, 429/42, 429/127, 429/68, 427/115, 502/101
• US Class Current: 429/405
• CPC Class Codes: H01M 10/4214 Arrangements for moving electrodes or electrolyte
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 12/06 with one metallic and one gaseous electrode
• CPC Class Codes: H01M 12/08 composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
• CPC Class Codes: H01M 2004/024 Insertable electrodes
• CPC Class Codes: H01M 2300/0085 Immobilising or gelification of electrolyte
• CPC Class Codes: H01M 4/42 Alloys based on zinc
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 50/46 Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: H01M 6/5011 for several cells simultaneously or successively
• CPC Class Codes: H01M 8/184 Regeneration by electrochemical means
• CPC Class Codes: H01M 8/186 by electrolytic decomposition of the electrolytic solution or the formed water product
• CPC Class Codes: H01M 8/22 Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y10T 29/49115 including coating or impregnating

Abstract

In an air-metal fuel cell battery (FCB) system, wherein metal-fuel tape, the ionically-conductive medium and the cathode structures are transported at substantially the same velocity at the locus of points at which the ionically-conductive medium contacts the moving cathode structure and the moving metal-fuel tape during discharging and recharging modes of operation. In a first generalized embodiment of the present invention, the ionically-conductive medium is realized as an ionically-conductive belt, and the metal-fuel tape, ionically-conductive belt, and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing belt contacts the metal-fuel tape and the cathode structure during system operation. In a second generalized embodiment of the present invention, the ionically-conductive medium is realized as a solid-state (e.g. gelatinous) film layer integrated with the metal-fuel tape, and the metal-fuel tape, ionically-conductive film layer and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing film layer contacts the metal-fuel tape and the cathode structure during system operation. In a third generalized embodiment of the present invention, the ionically-conductive medium is realized as a solid-state film layer integrated with the movable cathode structure, and the metal-fuel tape, ionically-conductive film layer and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing film layer contacts the metal-fuel tape and the cathode structure during system operation. By transporting the movable cathode structure, ionically contacting medium and metal-fuel tape within the system as described above, generation of frictional forces among such structures are minimized during system operation, and thus the damage to the cathode structure and metal-fuel tape is substantially reduced.

Claims

1. A cathode belt structure for use in a metal-air fuel cell battery system, comprising:

a flexible belt portion transportable between two or more support rollers during operation of said metal-air fuel cell battery system, said flexible belt portion further having an outer surface and a constitution allowing oxygen to flow through said outer surface along said flexible belt portion towards an ionically-conductive medium in contact with said outer surface during operation of said metal-air fuel cell battery system;

a catalytic medium embodied within said flexible belt portion, for supporting a catalytic reaction at the interface formed between said ionically-conductive medium and said outer surface as metal-fuel material is transported over said ionically-conductive medium in contact with said outer surface during operation of said metal-air fuel cell battery system; and

a current-collecting medium embodied within said flexible belt portion, for collecting electrical current produced as metal-fuel material is transported over said ionically-conductive medium in contact with said outer surface during operation of said metal-air fuel cell battery system.

2. The cathode belt structure of claim 1, wherein said ionically-conductive medium comprises a solid-state film having ionically-conductive properties, applied to said outer surface of said flexible belt portion.

3. The cathode belt structure of claim 1, wherein said ionically-conductive medium comprises a solid-state film that is gelatinous.

4. The cathode belt structure of claim 1, wherein said current collecting medium comprises a nickel mesh fabric or sponge material embedded with said catalytic material, carbon and binder material.

5. The cathode belt structure of claim 1, comprising a Fluoroethylene polymer.

6. The cathode belt structure of claim 1, wherein porosity of said flexible belt portion is the range from about 30 to about 70%, and thickness of said flexible belt portion is in the range from about 0.2 to about 0.6 millimeters.

7. A method of fabricating a cathode belt structure for use in a metal-air fuel cell battery system, said method comprising:

(a) blending sinterable powder with a binder material and catalyst material, in a solvent including water and surfactant in order to provide a slurry mixture;

(b) applying a coating of said slurry mixture onto a current collecting material to produce a slurry coated material;

(c) drying said slurry coated material to produce a dried article;

(d) compressing said dried article to form a sheet of porous flexible material;

(e) sintering said sheet of flexible material for a time period sufficient to remove said solvent therefrom and form a sheet of flexible cathode material;

(f) cutting said sheet of flexible cathode material to form a cathode belt structure having a pair of end portions; and

(g) joining the end portions of said cathode belt structure to form a virtually seamless cathode surface about a closed belt structure.

8. The method of claim 7, where in step (b) said current collecting material comprises nickel mesh or sponge material.

9. The method of claim 7, where in step (a) said binder material is fluoroetheylene polymer.

10. The method of claim 7, wherein said sinterable powder comprises black carbon powder.

11. The method of claim 7, where in step (c) said catalyst material is magnesium dioxide (MnO₂).

12. The method of claim 7, where during step (d) said dried article is compressed so that said sheet of flexible material has a porosity in the range from about 30 to about 70%, and thickness in the range from about 0.2 to about 0.6 millimeters.

13. The method of claim 7, which further comprises:

forming said ionically conducting medium on said sheet of flexible cathode material after step (e);

or

forming said ionically-conductive medium on said cathode belt structure after step (f).

14. The method of claim 13, where after step (e) or step (f), said ionically-conducting medium comprises a solid-state film having ionically-conductive properties.

15. The method of claim 14, where after step (e) or step (f), said solid-state film is gelatinous.