Flow field plate arrangement for a fuel cell
A fuel cell comprising anode and cathode flow field plates having a multitude of flow channels separated by land features wherein the land features of the anode side are wider than the land features of the cathode side is disclosed. In fuel cells, the flow field plate arrangement of the present invention provides higher power (lower cost per kW), improved durability, and less stringent assembly alignment.
1. A device comprising an electrochemical cell, said electrochemical cell comprising:
a membrane electrode assembly defining an anode side of said cell and a cathode side of said cell;
a first flow field plate for the cathode side of said cell, said first flow field plate comprising a plurality of first channels separated by first lands, wherein said plurality of first channels and first lands run between a first set of fluid manifolds; and
a second flow field plate for the anode side of said cell, said second flow field plate comprising a plurality of second channels separated by second lands, wherein said plurality of second channels and second lands run between a second set of fluid manifolds, wherein
said membrane electrode assembly is interposed between said first and second flow field plates,
a pitch defined by said first flow field plate is less than a pitch defined by said second flow field plate,
an adjacent pair of said first lands and an associated one of said second lands are each provided in a pattern of alternating angles and crests in a plane parallel to both of said flow field plates, said pattern of said adjacent pair of first lands and said pattern of said associated one of said second lands are orientated relative to each other across the membrane electrode assembly such that said adjacent pair of said first lands and said associated one of said second lands crisscross along said alternating angles and alternate crests of said adjacent pair of said first lands aligning in cross section with a crest of said associated one of said second lands and then a crest of one of said adjacent pair of said first lands aligning in cross section with one of said plurality of second channels, and
said pitch of each said first and second flow field plates is constant between said first and second sets of fluid manifolds.
2. The device according to claim 1 wherein the pitch defined by said second flow field plate is approximately twice as large as the pitch defined by said first flow field plate.
3. The device according to claim 1 wherein at least one of said second lands has a cross sectional width wider than a cross sectional width of at least one of said first lands.
4. The device according to claim 1 wherein said first channels define a cross sectional width approximately equal to a cross sectional width defined by said second channels.
5. The device according to claim 1 wherein a substantial number of said second lands define a cross sectional width greater than a cross sectional width defined by a substantial number of said first lands.
6. The device according to claim 1 wherein a substantial number of said second channels define a cross sectional width approximately equal to a cross sectional width defined by a substantial number of said first channels.
7. The device according to claim 1 wherein a majority of said second lands define a cross sectional width greater than a cross sectional width defined by a majority of said first lands.
8. The device according to claim 1 wherein a majority of said first channels define a cross sectional width approximately equal to a cross sectional width defined by a majority of said second channels.
9. The device according to claim 1 wherein substantially all of said second lands define a cross sectional width greater than a cross sectional width defined by substantially all of said first lands.
10. The device according to claim 1 wherein substantially all of said first channels define a cross sectional width approximately equal to a cross sectional width defined by substantially all of said second channels.
11. The device according to claim 1 wherein said first and second channels each have a cross sectional width of 1.5 mm or less.
12. The device according to claim 1 wherein each of said flow field plates have a thickness of 1 mm or less.
13. The device according to claim 1 wherein a cross sectional width of each said first lands is 1 mm or less.
14. The device according to claim 1 wherein a cross sectional width of each said second lands is about 3 times wider than a cross sectional width of each said first lands.
15. The device according to claim 14 wherein said first channels define a cross sectional width approximately equal to a cross sectional width defined by said second channels.
16. The device according to claim 1 wherein said first and second channels each have a depth of about 1 mm or less.
17. The device according to claim 1 wherein the pitch defined by said first flow field plate is about 2.5 mm or less.
18. The device according to claim 1 wherein said device further comprises structure defining a fuel cell of the proton exchange membrane type.
19. The device according to claim 18 wherein said device further comprises structure defining a vehicle powered by said fuel cell.
20. The device according to claim 1 wherein said first and second patterns ensure at least about 30% land-to-land alignment across said membrane electrode assembly interposed between said first and second flow field plates.
21. The device according to claim 1 wherein said first and second channels are serpentine.