Electrochemical fuel cell stack having staggered fuel and oxidant plenums

1. An electrochemical fuel cell stack comprising:

a plurality of electrochemical fuel cells, each comprising:

an anode and a cathode;

an anode plate having an active surface facing the anode and an oppositely facing non-active surface, wherein the anode plate active surface comprises a plurality of parallel linear fuel flow field channels, and the anode plate further comprises a fuel supply manifold opening and a fuel supply plenum that fluidly connects the fuel flow field channels to the fuel supply manifold opening, a fuel supply backfeed channel at least partially formed on the non-active surface of the anode plate, and a fuel supply backfeed port extending through the anode plate that fluidly connects the fuel supply backfeed channel and the fuel supply plenum, wherein the fuel supply backfeed channel of each fuel cell is also at least partially formed on the non-active surface of the adjoining cathode plate of an adjacent fuel cell; and

a cathode plate having an active surface facing the cathode and an oppositely facing non-active surface, wherein the cathode plate active surface comprises a plurality of parallel linear oxidant flow field channels, and the cathode plate further comprises an oxidant supply manifold opening and an oxidant supply plenum that fluidly connects the oxidant flow field channels to the oxidant supply manifold opening,

wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the fuel and oxidant supply plenums of the adjoining anode and cathode plates are staggered so as not to overlap in the direction perpendicular to the plane of the fuel cells,

wherein the total height of the fuel supply plenum plus the fuel supply backfeed channel is greater than the thickness of the anode plate.

2. The electrochemical fuel cell stack of claim 1 wherein:

the cathode plate of each fuel cell further comprises an oxidant supply backfeed channel at least partially formed on the non-active surface of the cathode plate, and a oxidant supply backfeed port extending through the cathode plate that fluidly connects the oxidant supply backfeed channel and the oxidant supply plenum.

3. The electrochemical fuel cell stack of claim 2 wherein:

the oxidant supply backfeed channel of each fuel cell is also at least partially formed on the non-active surface of the adjoining anode plate of an adjacent fuel cell.

4. The electrochemical fuel cell stack of claim 2 wherein the fuel supply backfeed port comprises the fuel supply plenum and the oxidant supply backfeed port comprises the oxidant supply plenum.

5. The electrochemical fuel cell stack of claim 1 , wherein:

the anode plate further comprises a fuel exhaust manifold opening and a fuel exhaust plenum that fluidly connects the fuel flow field channels to the fuel exhaust manifold opening; and

the cathode plate further comprises an oxidant exhaust manifold opening and an oxidant exhaust plenum that fluidly connects the oxidant flow field channels to the oxidant exhaust manifold opening,

wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the fuel and oxidant exhaust plenums of the adjoining anode and cathode plates are staggered so as not to overlap in the direction perpendicular to the plane of the fuel cells.

6. The electrochemical fuel cell stack of claim 5 wherein:

the anode plate of each fuel cell further comprises a fuel exhaust backfeed channel at least partially formed on the non-active surface of the anode plate, and a fuel exhaust backfeed port extending through the anode plate that fluidly connects the fuel exhaust backfeed channel and the fuel exhaust plenum; and

the cathode plate of each fuel cell further comprises an oxidant exhaust backfeed channel at least partially formed on the non-active surface of the cathode plate, and an oxidant exhaust backfeed port extending through the cathode plate that fluidly connects the oxidant exhaust backfeed channel and the oxidant exhaust plenum.

7. The electrochemical fuel cell stack of claim 6 wherein:

the fuel exhaust backfeed channel of each fuel cell is also at least partially formed on the non-active surface of the adjoining cathode plate of an adjacent fuel cell; and

the oxidant exhaust backfeed channel of each fuel cell is also at least partially formed on the non-active surface of the adjoining anode plate of an adjacent fuel cell.

8. The electrochemical fuel cell stack of claim 7 wherein the total height of the fuel exhaust plenum plus the fuel exhaust backfeed channel is greater than the thickness of the anode plate.

9. The electrochemical fuel cell stack of claim 7 wherein the total height of the oxidant exhaust plenum plus the oxidant exhaust backfeed channel is greater than the thickness of the cathode plate.

10. The electrochemical fuel cell stack of claim 6 wherein the fuel exhaust backfeed port comprises the fuel exhaust plenum and the oxidant exhaust backfeed port comprises the oxidant exhaust plenum.

11. The electrochemical fuel cell stack of claim 10 wherein the fuel and oxidant supply and exhaust backfeed ports of each fuel cell are rectangular in shape and extend along the ends of the fuel cells.

12. The electrochemical fuel cell stack of claim 5 , wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the fuel supply and exhaust plenums of the adjoining anode plate are staggered so as not to overlap either of the oxidant supply and exhaust plenums of the adjoining cathode plate, in the direction perpendicular to the plane of the fuel cells.

13. The electrochemical fuel cell stack of claim 12 wherein the fuel and oxidant supply and exhaust manifold openings form edge fuel and oxidant supply and exhaust manifolds.

14. The electrochemical fuel cell stack of claim 12 wherein the fuel and oxidant supply and exhaust manifold openings form end fuel and oxidant supply and exhaust manifolds.

15. The electrochemical fuel cell stack of claim 12 wherein the fuel and oxidant supply and exhaust manifold openings form side fuel and oxidant supply and exhaust manifolds.

16. The electrochemical fuel cell stack of claim 15 wherein:

the fuel supply and exhaust manifolds are positioned on the same side of the fuel cells; and

the oxidant supply and exhaust manifolds are positioned on the same side of the fuel cells.

17. The electrochemical fuel cell stack of claim 15 wherein:

the fuel and oxidant supply manifolds are positioned on opposing sides of the fuel cells; and

the fuel and oxidant exhaust manifolds are positioned on opposing sides of the fuel cells.

18. The electrochemical fuel cell stack of claim 5 , wherein each fuel cell further comprises:

a plurality of parallel linear coolant flow field channels formed on the non-active surfaces of the anode and cathode plates;

a first coolant supply manifold opening; and

a coolant supply plenum that fluidly connects the coolant flow field channels to the first coolant supply manifold opening,

wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the coolant supply plenum and the fuel and oxidant supply and exhaust plenums of the adjoining anode and cathode plates are staggered so as not to overlap in the direction perpendicular to the plane of the fuel cells.

19. The electrochemical fuel cell stack of claim 18 , wherein each fuel cell further comprises:

a first coolant exhaust manifold opening, and a coolant exhaust plenum that fluidly connects the coolant flow field channels to the first coolant exhaust manifold opening; and

wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the coolant exhaust plenum and the fuel and oxidant supply and exhaust plenums of the adjoining anode and cathode plates are staggered so as not to overlap in the direction perpendicular to the plane of the fuel cells.

20. The electrochemical fuel cell stack of claim 19 , wherein each fuel cell further comprises:

a second coolant supply manifold opening; and

a second coolant exhaust manifold opening,

wherein the coolant supply and exhaust plenums also fluidly connect the coolant flow field channels to the second coolant supply and exhaust manifold openings, respectively.

21. The electrochemical fuel cell stack of claim 20 wherein:

the first and second coolant supply and exhaust manifold openings form side first and second coolant supply and exhaust manifolds;

the first and second coolant supply manifolds are positioned on opposing sides of the fuel cells; and

the first and second coolant exhaust manifolds are positioned on opposing sides of the fuel cells.

22. An electrochemical fuel cell stack comprising:

a plurality of electrochemical fuel cells, each comprising:

an anode and a cathode;

an anode plate having an active surface facing the anode and an oppositely facing non-active surface, wherein the anode plate active surface comprises a plurality of parallel linear fuel flow field channels, and the anode plate further comprises a fuel supply manifold opening and a fuel supply plenum that fluidly connects the fuel flow field channels to the fuel supply manifold opening; and

a cathode plate having an active surface facing the cathode and an oppositely facing non-active surface, wherein the cathode plate active surface comprises a plurality of parallel linear oxidant flow field channels, and the cathode plate further comprises an oxidant supply manifold opening and an oxidant supply plenum that fluidly connects the oxidant flow field channels to the oxidant supply manifold opening, an oxidant supply backfeed channel at least partially formed on the non-active surface of the cathode plate, and a oxidant supply backfeed port extending through the cathode plate that fluidly connects the oxidant supply backfeed channel and the oxidant supply plenum, wherein the oxidant supply backfeed channel of each fuel cell is also at least partially formed on the non-active surface of the adjoining anode plate of an adjacent fuel cell,

wherein, with respect to each adjoining anode plate and cathode plate in a pair of adjacent fuel cells in the stack, the fuel and oxidant supply plenums of the adjoining anode and cathode plates are staggered so as not to overlap in the direction perpendicular to the plane of the fuel cells,

wherein the total height of the oxidant supply plenum plus the oxidant supply backfeed channel is greater than the thickness of the cathode plate.