Amorphous carbon coatings for fuel cell bipolar plates
View Patent ↗A flow field plate for fuel cell applications includes a metal with a non-crystalline carbon layer disposed over at least a portion of the metal plate. The non-crystalline carbon layer includes an activated surface which is hydrophilic. Moreover, the flow field plate is included in a fuel cell with a minimal increase in contact resistance. Methods for forming the flow field plates are also provided.
1. A method of making a flow field plate, the flow field plate comprising:
a metal plate having a first surface and a second surface, the first surface defining a plurality of channels for directing flow a first gaseous composition; and
a non-crystalline carbon layer disposed over at least a portion of the metal plate, the non-crystalline carbon layer having a carbon layer surface with a contact angle less than about 30 degrees, the method comprising:
depositing the non-crystalline carbon layer on the metallic plate; and
activating the carbon layer surface;
such that the carbon layer surface is an activated surface having nitrogen atoms.
2. The method of claim 1 wherein the carbon layer surface is activated with a plasma.
3. The method of claim 2 wherein the plasma is DC plasma, an RF plasma, microwave plasma, or a hot filament plasma.
4. The method of claim 1 wherein the carbon layer surface is chemically activated.
5. The method of claim 1 wherein the carbon layer surface is pre-conditioned prior to deposition of the non-crystalline carbon layer.
6. The method of claim 1 wherein the contact angle less than 20 degrees.
7. The method of claim 1 wherein the carbon layer has wherein the carbon layer is doped with a dopant atom.
8. The method of claim 7 wherein the carbon layer has wherein the dopant atom is a metal atom.
9. The method of claim 1 wherein the carbon layer has wherein the non-crystalline carbon layer comprises amorphous carbon.
10. The method of claim 1 wherein the carbon layer has wherein the carbon layer includes less than about 10 weight percent crystalline carbon.
11. The method of claim 1 wherein the carbon layer surface includes oxygen atoms.
12. The method of claim 1 wherein the carbon layer surface includes on average at least 5 pores per μm 2 .
13. The method of claim 1 wherein the carbon layer has a roughness average from about 200 to about 1000 nm.
14. The method of claim 1 wherein the carbon layer has wherein the second surface defines a second plurality of channels for directing flow of a second gaseous composition.
15. The method of claim 1 wherein the carbon layer has wherein a second non-crystalline carbon layer is deposited on the second surface.