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Expanded graphite/epoxy/aliphatic amine composites for bipolar plates applications in polymer electrolyte fuel cells

Abstract:

Suitable conductive fillers for resins and processing conditions are critical factors for the final properties of composite bipolar plates. This research is focused on the development of expanded graphite/epoxy/aliphatic amine composite as a potential replacement for conventional bipolar plates to meet global standards of Polymer Electrolyte Fuel Cells (PEFCs). The synergistic effects on the electrical conductivity of secondary fillers Carbon Black (CB) and Graphite Nano-platelets (GNP) with Expanded Graphite (EG) were studied in a diglycidyl ether of bisphenol A (DGEBA) epoxy/polyether triamine system. Compositions of secondary filler were varied in proportions of 5, 10, 15 and 20 wt % in a fixed 40 wt % EG / Epoxy resin (w/w) to find the right secondary fillers under direct mixing without solvent. A 10 wt % CB displayed the highest electrical conductivity around 3.05x10-2 S/cm. For a 60 wt % EG/10 wt % CB composite, the electrical conductivity (in plane) and flexural strength were at about 19 S/cm and 22 MPa, respectively.