Coke and graphite filled separator plate for electrochemical cells

• US 4,592,968 A
• Filed: 07/18/1985
• Issued: 06/03/1986
• Est. Priority Date: 07/18/1985
• Status: Expired due to Fees

• Current Assignee: International Fuel Cells Corporation
• Original Assignee: International Fuel Cells Corporation
• Inventors: Taylor, William A.
• Primary Examiner(s): Skapars, Anthony
• Application Number:
  US06/756,473
• Time in Patent Office: 320 Days
• Field of Search: 429/34, 429/247, 429/249, 429/251, 429/253, 264/29.5, 264/29.7, 264/105, 264/236, 423/499
• US Class Current: 429/509
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• CPC Class Codes: H01M 8/0213 Gas-impermeable carbon-containing materials
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electrochemical cell separator plate formed from a composition of carbonizable resin, coke, and graphite particles, and methods of making and using the same. The separator plate has an improved balance of properties such as flexural modulus. The plates are formed by molding a composition of carbonizable resin, coke, and graphite particles, surface grinding the plate and then carbonizing and graphitizing the plate. The composition comprises about 40% to about 60% of carbonizable resin and about 60% to about 40% of a coke-graphite mixture. The coke-graphite mixture comprises about 30% to about 90% of coke particles and about 70% to about 10% of graphite particles. These separator plates may be used in, for example, fuel cells.

Claims

1. An electrochemical cell separator plate comprising a molded, carbonized and graphitized product formed from a carbonizable and graphitizable molding composition wherein the improvement utilizing a carbonizable and graphitizable molding comprises composition comprising:

about 40 weight % to about 60 weight % of carbonizable resin; and

about 60 weight % to about 40 weight % of a coke-graphite mixture;

said coke particles having size less than 149 microns and said graphite particles having size less than 120 microns.

the coke-graphite mixture comprising about 30 weight % to about 90 weight % of coke particles and about 70 weight % to about 10 weight % of graphite particles.

2. The separator plate of claim 1 wherein the coke has a particle size distribution such that about 50% to about 80% of the coke particles are less than about 44 microns in size and substantially all coke particles are less than 149 microns in size.

3. The separator plate of claim 1 wherein the graphite has a particle size distribution such that about 0% to about 5% of the graphite particles are less than about 15 microns in size, about 95% to about 100% of the graphite particles are less than 120 microns in size and about 50% to 60% of the graphite particles are about 50 to about 60 microns in size.

4. The separator plate of claim 1 wherein the carbonizable resin is a carbonizable phenolic resin such as a phenol-aldehyde resol or a phenol-aldehyde novolac.

5. An electrochemical fuel cell separator plate wherein the plate is formed from a carbonizable and graphitizable molding composition by molding at sufficient heat and pressure to densify the plate, grinding the plate surface and then heating at a sufficient temperature to carbonize and then graphitize the plate, wherein the improvement comprises using as the molding composition a mixture comprising:

about 40 weight % to about 60 weight % of carbonizable resin; and

about 60 weight % to about 40 weight % of a coke-graphite mixture;

said coke particles having size less than 149 microns and said graphite particles having size less than 120 microns.

the coke-graphite mixture comprising about 30 weight % to about 90 weight % of coke particles and about 70 weight % to about 10 weight % of graphite particles.

6. The separator of claim 5 wherein the coke has a particle size distribution such that about 50% to about 80% of the coke particles are less than about 44 microns in size and substantially all coke particles are less than 149 microns in size.

7. The separator plate of claim 5 wherein the graphite has a particle size distribution such that up to about 5% of the graphite particles are less than about 15 microns in size, about 95% to about 100% of the graphite particles are less than 120 microns in size and about 50% to 60% of the graphite particles are about 50 microns to about 60 microns in size.

8. The separator plate of claim 5 wherein the carbonizable resin is a carbonizable phenolic resin such as a phenol-aldehyde resol or a phenol-aldehyde novolac.

9. A fuel cell comprising at least one anode, at least one cathode, electrolyte material and at least one carbonized and graphitized separator plate formed from a carbonizable and graphitizable molding composition, wherein the improvement comprises utilizing a carbonizable and graphitizable molding composition comprising:

about 40 weight % to about 60 weight % of carbonizable resin; and

about 60 weight % to about 40 weight % of a coke-graphite mixture;

said coke particles having size less than 149 microns and said graphite particles having size less than 120 microns.

the coke-graphite mixture comprising about 30 weight % to about 90 weight % of coke particles and about 70 weight % to about 10 weight % of graphite particles.

10. The fuel cell of claim 9 wherein the coke has a particle size distribution such that about 50% to about 80% of the coke particles are less than about 44 microns in size and essentially all coke particles are less than 149 microns in size.

11. The separator plate of claim 9 wherein the graphite has a particle size distribution such that up to about 5% of the graphite particles are less than about 15 microns in size, about 95% to about 100% of the graphite particles are less than 120 microns in size and about 50% to 60% of the graphite particles are about 50 microns to about 60 microns in size.

12. The fuel cell of claim 9 wherein the carbonizable resin is a carbonizable phenolic resin such as a phenol-aldehyde resol or a phenol-aldehyde novolac.