Carbon/Carbon Composite Bipolar Plate for Proton Exchange Membrane Fuel Cells

Carbon/carbon‐composite bipolar plates for proton exchange membrane fuel cells (PEMFC) have been fabricated by slurry molding a chopped‐fiber preform followed by sealing with chemically vapor‐infiltrated carbon. The resulting component is hermetic with respect to through‐thickness leakage and has a high electronic conductivity (200–300 S/cm) as a result of the deposited graphitic carbon. The material has a low density due to retained porosity resulting in a low‐weight component. Biaxial flexure strength was measured to be 175 ± 26 MPa. Cell testing of a active area, single‐sided plate indicated very low cell resistance and high efficiency, but with a somewhat steep drop‐off in voltage with current at high values. Corrosion testing indicated minimal corrosion in fuel cell environments.