The Effects of Conductive Additives on the Overall Performance of Composite Bipolar Plate in PEMFCs

Obtaining high electrical properties on high mechanical performance of composite bipolar plates (CBP) is crucial for their application in proton exchange membrane fuel cells (PEMFC). Various conductive additives have been investigated for electrical enhancement; while the effects on overall properties of CBP has not been systematically evaluated. Hence, in this study, we report overall properties evaluation of epoxy resin base CBPs with four different conductive additives. Overall properties of theses CBPs are tested, including electrical conductivity, mechanical properties, hydrophobic properties and corrosion resistance. The results indicate the electrical conductivity of CBP could be enhanced by the minor additive such as carbon (CB) and carbon nanotubes (CNT). Further, the mechanical properties would be enhanced by the addition of CNT; while the mechanical properties would be weakened with the addition of CB. Moreover, the addition of carbon fiber (CF) would enhance the mechanical properties, but the electrical conductivity and thermal conductivity would be weakened. Due to the special structure of expand graphite (EG), the CBP with EG exhibits excellent overall performance. Specifically, CBP with 20% EG and 5% CF exhibits well, which could meet all properties requirement of Department of Energy (DOE) target. This work could provide a guideline for researchers investigating CBP formulation and highlights the challenges between additive structure and CBP performance.