Corrosion resistant PEM fuel cell

• US 6,372,376 B1
• Filed: 12/07/1999
• Issued: 04/16/2002
• Est. Priority Date: 12/07/1999
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Cunningham, Kevin M., Borup, Rodney Lynn, Fronk, Matthew Howard, Hulett, Jay S., Brady, Brian K.
• Primary Examiner(s): Chaney, Carol
• Assistant Examiner(s): DOVE, TRACY MAE
• Application Number:
  US09/456,478
• Time in Patent Office: 861 Days
• Field of Search: 429/30, 429/38, 429/44, 429/41
• US Class Current: 429/487
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0213 Gas-impermeable carbon-containing materials
• CPC Class Codes: H01M 8/0226 in the form of mixtures
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

Claims

1. In a PEM fuel cell having at least one cell comprising a pair of opposite polarity electrodes, a membrane electrolyte intedacent said electrodes for conducting ions therebetween, and an electrically conductive contact element having a working face confronting at least one of said electrodessfor conducting electrical current from said one electrode, the improvement comprising:

said contact element comprising a corrosion-susceptible metal substrate and an electrically conductive, corrosion-resistant protective coating on said face to protect said substrate from the corrosive environment of said fuel cell, said protective coating comprising a mixture of electrically conductive particles dispersed throughout an oxidation-resistant and acid-resistant, water-insoluble polymeric matrix and having a resistivity greater than about 50 ohm-cm, said mixture comprising graphite particles having a first particle size and other electrically conductive particles selected from the group consisting of gold, platinum, nickel, palladium, rhodium, niobium, titanium carbide, titanium nitride, titanium diboride, chromium-alloyed titanium, nickel-alloyed titanium, rare earth metals and carbon, said other particles having a second particle size less than said first particle size to enhance the packing density of said particles.

2. A fuel cell according to claim 1 wherein said carbon comprises carbon black.

3. A fuel cell according to claim 1 wherein said coating is electrophoretically deposited onto said substrate from a suspension of said particles in an aqueous solution of acid-solubilized polymer.

4. A fuel cell according to claim 1 wherein a discrete film of said coating is laminated onto said substrate to form said electrically conductive contact element.

5. A fuel cell according to claim 1 wherein a precursor of said coating is deposited onto said substrate from a solution thereof, dried and cured to form said coating.

6. A fuel cell according to claim 1 wherein said substrate comprises a first acid-soluble metal underlying a second acid-insoluble, passivating metal layer susceptible to oxidation in said environment.

7. A fuel cell according to claim 1 wherein said polymer matrix is selected from the group consisting of epoxies, silicones, polyamide-imides, polyether-imides, polyphenols, fluro-elastomers, polyesters, phenoxy-phenolics, epoxide-phenolics, acrylics and urethanes.

8. In a PEM fuel cell having at least one cell comprising a pair of opposite polarity electrodes, a membrane electrolyte intedjacent said electrodes for conducting ions therebetween, and an electrically conductive contact element having a working face confronting at least one of said electrodes for conducting electrical current from said one electrode, the improvement comprising:

said contact element comprising a corrosion-susceptible metal substrate and an electrically conductive, corrosion-resistant protective coating on said face to protect said substrate from the corrosive environment of said fuel cell, said protective coating comprising a plurality of electrically conductive particles dispersed throughout an oxidation-resistant and acid-resistant, water-insoluble polymeric matrix and having a resistivity no greater than about 50 ohm-cm, said substrate comprising a first acid-soluble metal underlying a second acid-insoluble, passivating layer susceptible to oxidation in said environment.