Comparison of Compression Molding and Selective Laser Sintering Processes in the Development of Composite Bipolar Plates for Proton Exchange Membrane Fuel Cells

Bipolar plates are key components of Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In order to attain these goals, we have manufactured graphite-carbon- polymer composite plates using Compression Molding (CM), which is suitable for mass production, and Selective Laser Sintering (SLS), which is suitable for making prototypes. In this paper, the electrical conductivity and flexural strength of the bipolar plates fabricated using the CM process versus constitutive materials are experimentally studied. The properties of bipolar plates fabricated using the CM process are compared with those of plates fabricated using the SLS process. Natural graphite (NG), synthetic graphite (SG), carbon black (CB), and carbon fiber (CF) are used as the constitutive materials for both processes, with epoxy resin employed as the binder matrix. By varying the volume fraction of each constituent, the distribution of the electrical conductivity and flexural strength of parts made using the CM and SLS processes are obtained, and the similarities and differences of the effects of the various constituents between these two processes are compared