Evaluation of graphite composite bipolar plate for PEM (proton exchange membrane) fuel cell: Electrical, mechanical, and molding properties

The bipolar plate is a major component of the proton exchange membrane (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 electric properties, specimens made with different mixing ratio, processing pressure and temperature were tested. To increase mechanical strength, one or two layers of woven carbon fabric were added to the original graphite and resin composite. For surface properties, contact angle and surface roughness were tested. Flow channels were fabricated by compression molding with design of experiments (DOEs) to evaluate moldability.