Patent ID: 6858341

Claim:
A fuel cell stack, comprising: a pair of end plates; a plurality of membrane-electrode assemblies arranged in series between the pair of end plates; and a bipolar plate assembly operatively interposed between adjacently situated membrane-electrode assemblies, wherein the bipolar plate assembly includes a structural layer of a structural metal, a conductive layer of a conductive metal intermetallically diffused to the structural layer, and a flow field at least partially defined by the conductive layer, wherein the structural metal and the conductive metal have different compositions, wherein the structural metal has a higher strength-to-weight ratio than the conductive metal, wherein the conductive layer includes opposed first and second faces, wherein the first face is intermetallically diffused to the structural layer where the first face abuts the structural layer, and further wherein the flow field extends from an opening in the second face toward the first face and comprises of at least one channel from which the conductive metal has been removed to define laterally spaced sidewalls and a bottom.