Exploring the potential of polyethylene/epoxy/graphite composite as bipolar plate material for proton exchange membrane fuel cell

Abstract

On account of their low-cost, corrosion resistance, and lightweight, carbon-polymer composites (CPCs) are very promising for producing bipolar plates (BPs) for proton exchange membrane fuel cells (PEMFCs). However, the substantial conductive filler concentration that is required to give CPCs with the desired level of electrical conductivity for BP application often results in difficulty in processing and degradation in mechanical strength. In this study, the potential of polyethylene (PE)/epoxy/graphite composite to yield BPs with electrical and mechanical performance that meet the technical targets for commercial PEMFC BPs was explored. PE/epoxy/graphite composites with varying graphite contents were prepared by melt mixing followed by compression moulding. The morphology, flexural properties, and electrical conductivity of the composites were investigated. The electrical conductivity and flexural modulus of the composites increased with increase in graphite content while the flexural strength increased with graphite content up to a maximum of 42.1 MPa at 70 wt% graphite and then decreased with further increase in graphite content. With respect to the United States Department of Energy (DOE) targets, the PE/epoxy/80 wt% graphite composite has the most promising combination of electrical conductivity (72.96 Scm-1 for inplane and 4.12 Scm-1 for through-plane) and flexural strength (39.15MPa). Although the electrical conductivities of the PE/epoxy/graphite composites are still below the DOE targets, achieving this level of conductivities with a single filler indicates that the composites have promising potential for CPC BP applications.