Hydrolytically-stable hydrophilic coatings for PEMFC bipolar plate
View Patent ↗Bipolar plates useful for fuel cell applications include a plate body having a channel-defining surface that is at least partially coated with a hydrophilic layer. This hydrophilic layer comprises residues of a silane-coupling agent in a sufficient amount such portions of the first hydrophilic layer have a contact angle less than a predetermined value.
1. A method of forming a bipolar plate having a hydrophilic coating, the method comprising:
contacting a plate body with a silane coupling agent, the plate body having a channel-defining surface; and
curing the silane coupling agent to form an unactivated first layer on the plate body;
contacting the unactivated layer with an acid composition to form an activated first layer,
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 hydrocarbon-containing moiety providing a spatial separation between Q 1 and the Si(R 1 ) 3 group; and
Q 2 is a moiety having one or more atoms that hydrogen bond or have energetically favorable interactions with water.
2. The method of claim 1 wherein the bipolar plate has a contact angle less than about 60 degrees.
3. The method of claim 1 wherein the bipolar plate has a contact angle less than about 30 degrees.
4. The method of claim 1 further comprising:
coating the activated first coating with a second hydrophilic layer.
5. The method of claim 4 wherein the second hydrophilic layer has a contact angle less than about 15 degrees.
6. The method of claim 1 wherein the first layer includes residues of a colloidal silica.
7. The method of claim 1 wherein the channel-defining surface defines a set of fluid flow channels configured to distribute flow of a fluid across at least one side of the plate.
8. The method of claim 1 wherein the silane coupling agent has formula II:
(R 1 ) 3 SiQ 2 Si(R 1 ) 3 II.
9. The method of claim 1 wherein the silane coupling agent is bis-1,2-(triethoxysilyl)ethane (“BTSE”).
10. The method of claim 1 where the silane coupling agent has one or more of the following formulae:
wherein:
X is a halogen; and
m, n, and o are each independently an integer from 0 to 10.
11. The method of claim 1 wherein the silane coupling agent has one or more of the following formulae:
12. The method of claim 1 wherein the coupling agent has the following formula:
wherein:
R 1 is an alkoxy or a halogen; and
n is integer from 0 to 10.