Feasibility study on carbon-felt-reinforced thermoplastic composite materials for PEMFC bipolar plates

Polymer electrolyte membrane fuel cells (PEMFCs) have high efficiency, a low operating temperature, and nearly zero environmental emissions. The bipolar plate is one of the main components of the PEMFC because it accounts for a large part of the weight, volume, and cost. Recently, carbon-fiber-reinforced thermoplastic composite bipolar plates for PEMFCs have attracted interest owing to their simple fabrication method, high flexibility, excellent corrosion resistance, and damage resistance. The efficiency of PEMFCs depends primarily on the performance of the bipolar plates; however, composite bipolar plates have a high surface electrical contact resistance because of their resin-rich area. In this study, carbon felt was used to fabricate bipolar plates for PEMFCs. In addition, a solution impregnation method and the double percolation effect on the electrical conduction were introduced to improve the impregnation state of the thermoplastic polymer and the electrical conductivity of the composite plates simultaneously. The area specific resistance, double percolation morphology, and impregnation state of the composite plates were analyzed using the four-point probe method, transmission electron microscopy analysis, and scanning electron microscopy analysis, respectively. The results of the experiments were compared with the United States Department of Energy's technical targets for bipolar plates.