Conductive and hydrophilic coating for PEMFC bipolar plate
An electrically conductive plate for fuel cell applications comprises a plate body having at least one channel-defining surface and an electrically conductive hydrophilic layer disposed over at least a portion of the channel-defining surface. The electrically conductive layer includes residues of a silane coupling agent and electrically conductive hydrophilic carbon.
1. An electrically conductive plate for incorporation into a fuel cell, the plate comprising:
a plate body having a channel-defining surface;
an electrically conductive hydrophilic layer disposed over at least a portion of the surface of the plate body, the layer comprising:
residues of a silane-coupling agent; and
electrically conductive hydrophilic carbon wherein the hydrophilic carbon comprises a carbon component with an appended hydrophilic component.
2. The plate of claim 1 further comprising an intermediate conductive layer between the plate body and the hydrophilic layer.
3. The plate of claim 2 wherein the intermediate conductive layer comprises a metal or a conductive metal oxide or a conductive carbon.
4. The plate of claim 1 wherein the carbon component is selected from the group consisting of carbon black, graphite, carbon fiber, amorphous carbon, carbon nanotubes, and combinations thereof.
5. The plate of claim 1 wherein the hydrophilic component comprises a moiety having the following formula:
HG(Ar)—
wherein:
— represents the bond to the carbon component;
HG is a hydrophilic group; and
Ar is absent or an aromatic group.
6. The plate of claim 5 wherein HG is OR, COR, COOR, OCOR, COOM, halogen, CN, NR 2 , SNSO 3 H, SO 3 M, NR(COR), CONR 2 , NO 2 , PO 3 H 2 , PO 3 HM, NR 3 + X − , or PR 3 + X − , where R is independently H, C 1 -C 20 alkyl, or aryl; n is an integer from 1 to 8; M is a metal; and X − is a halide anion or anion derived from a mineral or organic acid.
7. The plate of claim 1 wherein the silane-coupling agent has formula I:
Q 2 -Q 1 -Si(R 1 ) 3 I
wherein:
R 1 is an alkoxy or a halogen;
Q 1 is a moiety having one or more atoms that hydrogen bond or have energetically favorable interactions with water; and
Q 2 is a hydrocarbon-containing moiety providing a spatial separation between Q 1 and the Si(R 1 ) 3 group.
8. The plate of claim 5 wherein the carbon component comprises electrically conductive particles selected from the group consisting of particulate carbonaceous compounds, crystalline carbon, carbon fiber, amorphous carbon, carbon black, carbon black aggregates, graphite, carbon composites, carbon-coated particles, coated hybrid carbon-based particles and mixtures thereof.
9. The plate of claim 8 wherein the carbon black is present in an amount from about 0.1 to 5 percent of silane solution.
10. An electrically conductive plate for incorporation into a fuel cell, the plate comprising:
a plate body having a channel-defining surface;
an intermediate electrically conductive layer disposed over the channel defining surface;
an electrically conductive hydrophilic layer disposed over the intermediate electrically conductive layer, the electrically hydrophilic conductive layer comprising:
residues of a silane coupling agent; and
electrically conductive hydrophilic carbon.
11. The plate of claim 10 wherein the hydrophilic carbon comprises a carbon component with an appended hydrophilic component.
12. The plate of claim 11 wherein the hydrophilic component comprises a moiety having the following formula:
HG(Ar)—
wherein:
— represents the bond to the carbon component;
HG is a hydrophilic group; and
Ar is absent or an aromatic group.
13. The plate of claim 10 wherein the silane coupling agent has formula I:
Q 2 -Q 1 -Si(R 1 ) 3 I
wherein:
R 1 is an alkoxy or a halogen;
Q 1 is a moiety having one or more atoms that hydrogen bond or have energetically favorable interactions with water; and
Q 2 is a hydrocarbon-containing moiety providing a spatial separation between Q 1 and the Si(R 1 ) 3 group.