Design of tunnel layout for a more uniformed contact pressure distribution at the intersection between metal bead seal and tunnel

A fuel cell comprising

• a cathode catalyst layer;
• an anode catalyst layer;
• an ion conducting membrane interposed between the cathode catalyst layer and the anode catalyst layer;
• a first gas diffusion layer disposed over and adjacent to the cathode catalyst layer;
• a second gas diffusion layer disposed over and adjacent to the anode catalyst layer;
• a first flow field disposed over and adjacent to the first gas diffusion layer;
• and
• a second flow field disposed over and adjacent to the second gas diffusion layer, the first flow field and second flow field each independently comprising:
• a first metal plate defining a first opening for providing a first reactant gas to a fuel cell, a first metal bead that surrounds the first opening, the first metal bead being an embossment in the first metal plate that defines a first channel, a first plurality of tunnels that provide a passage into and out of the first metal bead, each tunnel of the first plurality of tunnels having an inlet tunnel section that leads to the first metal bead and an outlet tunnel section that extends from the first metal bead to provide the first reactant gas to first reactant gas flow channels defined by the first metal plate, the inlet tunnel section being offset from the outlet tunnel section;
• and
• a second metal plate that aligns with the first metal plate.