Integrated carbon composite bipolar plate for polymer–electrolyte membrane fuel cells

The electrical resistance of bipolar plates for polymer–electrolyte membrane fuel cells (PEMFCs) should be very low to conduct the electricity generated with minimum electrical loss. The resistance of a bipolar plate consists of the bulk material resistance and the interfacial contact resistance when two such plates are contacted to provide channels for fuel and air (oxygen) supplies. Since the interfacial contact resistance is much larger than the bulk resistance in an actual fuel cell stack, an integrated carbon composite bipolar plate is developed in this study to eliminate the contact resistance between contacting bipolar plates. To fabricate this plate with channels for fuel, air and coolant, many stainless-steel pipes of 1 mm diameter are uniformly embedded in the carbon fiber/epoxy composite prepreg and co-cured. The contact resistance, flexural strength and thermal degradation temperatures of the developed composite bipolar plate are then measured.