Fuel cell flow field plate

Abstract

A fuel cell stack comprising a plurality of fuel cells, each having an anode flow field plate, a cathode flow field plate and a membrane electrode assembly disposed between the flow field plates. The anode and cathode flow field plates have primary channels and ribs separating the primary channels. At least a portion of the anode and cathode primary channels are disposed directly opposite one another with a membrane exchange assembly therebetween and with at least some of the ribs on the anode and cathode flow field plates located directly opposite one another to sandwich the membrane exchange assembly therebetween. The flow field plates can also have inlet distribution and outlet collection channels. Each of these distribution and collection channels is connected to a plurality of the primary channels, preferably located centrally, so as to improve flow distribution of the reactants.

1 . A flow field plate, for use in a fuel cell, the flow field plate being generally planar and having front and rear faces, wherein the flow field plate includes at least one first gas inlet aperture and at least one first gas outlet aperture, and wherein on the front face of the flow field plate there is provided at least one inlet distribution channel in communication with the first gas inlet, at least one outlet collection channel extending towards and in communication with the first gas outlet and a plurality of primary channels extending between said at least one gas distribution channel and said at least one outlet collection channel.  
     
     
         2 . A flow field plate as claims in  claim 1 , which includes a plurality of first gas inlets and a plurality of first gas outlets.  
     
     
         3 . A flow field plate as claimed in  claim 1 , which includes a plurality of gas inlet distribution flow channels and a plurality of gas outlet collection flow channels, and wherein each of the gas inlet distribution and gas outlet collection flow channels is connected to a plurality of the primary channels.  
     
     
         4 . A flow field plate as claimed in  claim 3 , wherein the primary channels extend generally parallel to one another, and wherein the gas inlet distribution and gas outlet collection channels extend generally perpendicularly thereto.  
     
     
         5 . A flow field plate as claimed in  claim 1 , which includes at least one second gas inlet aperture and at least one second gas outlet aperture.  
     
     
         6 . A flow field plate as claimed in  claim 5 , which includes, for at least one of the apertures, an aperture extension extending on the rear side of the flow field plate, for each aperture extension, at least one slot associated therewith and extending through the flow field plate from the rear side to the front side thereof, to provide communication between the corresponding aperture extension and corresponding one of said at least one inlet distribution channel and said at least one outlet collection channel.  
     
     
         7 . A flow field plate as claimed in  claim 6 , wherein each of the second gas inlet and outlet apertures includes an aperture extension, complementary with another flow field plate including slots therethrough for feeding the second gas through said other flow field plate to a front face thereof.  
     
     
         8 . A flow field plate as claimed in  claim 3 , wherein each of the first gas inlet and outlet apertures includes an aperture extension and associated therewith at least one slot for feeding gas through the flow field plate to the inlet distribution channels and back from the outlet collection channels.  
     
     
         9 . A flow field plate as claimed in  claim 8 , wherein each slot associated with each first gas inlet aperture is connected, on the front face to two gas inlet distribution channels, and each slot associated with the first gas outlet aperture is connected to two gas outlet collection channels.  
     
     
         10 . A flow field plate as claimed in  claim 8 , which includes sealing surfaces on the front and rear sides, for forming a seal with adjacent elements of fuel cell, wherein the sealing surface on the front side of the flow field plate includes, for each first gas inlet and outlet aperture, a first sealing surface portion enclosing the corresponding aperture and separating associated slots from the first gas inlet and outlet apertures and on the rear side thereof, a second sealing surface portion enclosing together each of the first gas inlet and outlet apertures and said at least one slot associated therewith.  
     
     
         11 . A flow field plate as claimed in  claim 10 , wherein each aperture extension is provided with a plurality of projections, defining flow channels extending from the apertures to the slots associated therewith.