Influence of different carbon materials on electrical properties of epoxy-based composite for bipolar plate applications

Abstract

During the last years, polymer composite bipolar plates have been developed from appropriate carbon materials and polymers. Considering these materials, several factors influence the effective electrical properties of bipolar plates for polymer electrolyte fuel cell (PEFC) applications. This research focuses on the development of a composite of graphite/epoxy resin/aliphatic amine, which be technically feasible as a material for use in PEFC and meet international commercial standards. A synergic mixture of Expanded Graphite (EG) as a primary filler and different secondary fillers was analyzed. The effect of Carbon Black (CB) and Graphite Nanoplatelets (GNP) as secondary fillers in proportions of 0, 0.5, 1, 2, and 3 wt% on EG with particle size greater than 300 µm and content of 40 wt% are analyzed. The methodology in this composite processing did not include any solvent and relatively low temperature processing is performed. The processing conditions were studied to understand the impact on the electrical properties of the composite. The best results were obtained with carbon black at 1%, obtaining an in-plane electrical conductivity at about 50 S/cm. The appropriate dispersion of the CB through the Epoxy/EG matrix creates bridges connecting plates that improve the flow of electrons compared to GNP composites.