Carbon/carbon composite bipolar plate for proton exchange membrane fuel cells

Carbon/carbon-composite bipolar plates for proton exchange membrane fuel ce lls (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 gr aphitic carbon. The material has a low density (0.96 g/cm(3)) due to retain ed porosity resulting in a low-weight component. Biaxial flexure strength w as measured to be 175 +/- 26 MPa. Cell testing of a 100 cm(2) 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. (C ) 2000 The Electrochemical Society. S0013-4651(99)09-074-6. All rights rese rved.