Manufacturing and Evaluation of Fiber-Reinforced Composite Bipolar Plate for PEM Fuel Cell

The fuel cell is one of promising environment-friendly energy sources for the next generation. The bipolar plate is a major component of the PEM fuel cell stack, which takes a large portion of stack cost. In this study, as alternative materials for bipolar plate of PEM fuel cells, graphite composites were fabricated by compression molding. Graphite particles mixed with epoxy resin were used as the main substance to provide electric conductivity. To achieve desired electrical properties, specimens were made with different mixing ratio, processing pressure and temperature and tested. To increase mechanical strength, one or two layers of woven carbon fabric were added to the original graphite and resin composite. Thus, the composite material was consisted of three phases: graphite particles, epoxy resin, and carbon fabric. By increasing mixing ratio of graphite, fabricated pressure and process temperature, electric conductivity of the composite were improved. The results of tensile test showed that the tensile strength of the two-phase graphite composite was about 4 MPa, and that of three-phase composite was increased to 57 MPa. As surface properties, contact angle and surface roughness were tested. Contact angles were higher than 100°. The average surface roughness was 0.96 μm.