Patent ID: 8278000

Claim:
A fuel cell comprising: a membrane electrode assembly; first-side separator plates disposed on a first side of the membrane electrode assembly, the first-side separator plates comprising: a first separator plate, a second separator plate, and a third separator plate, the first-side separator plates forming a first group of channels on the membrane electrode assembly for conducting a first reactant, the first group of channels including a first set and a second set of channels alternatively positioned, wherein each channel of the first set of channels is positioned adjacent to a channel of the second set, wherein the first set of the first group of channels includes a first sub-set of channels and a second sub-set of channels, wherein each channel of the first sub-set of channels communicates with a corresponding channel of the second sub-set of channels through a hole, wherein the second set of the first group of channels includes a first sub-set of channels and a second sub-set of channels, wherein each channel of the first sub-set of channels communicates with a corresponding channel of the second sub-set of channels through a hole, and wherein the first separator plate forms the first sub-set of channels of the first set and the first sub-set of channels of the second set with the membrane electrode assembly, the second separator plate forms a third group of channels for conducting coolant with the first separator plate, and the third separator plate forms the second sub-set of channels of the first set and the second sub-set of channels of the second set with the second separator plate; and a second-side separator plate disposed on a second side of the membrane electrode assembly forming a second group of channels on the second side of the membrane electrode assembly for conducting a second reactant, wherein each of the two sets of channels includes an input controlled by an input valve and an output controlled by an output valve, wherein the first group of channels forms an interdigitated flow field by closing the input valve of one of the two sets of channels and closing the output valve of the other of the two sets of channels, and forms a conventional flow field by opening both the input valve and the output valve.