Abstract
The performance and durability of proton exchange fuel cells (PEMFCs) are greatly affected by the bipolar plate (BP). In this paper, the thermal and electrical conductivities and mechanical property of graphite filled with resin composite BPs were collectively enhanced through the effectively coupled manipulations of molding pressure and impregnation pressure. The microstructures show that the resin tends to distribute at the top region of the rib under high impregnation pressure. The thermal and electrical conductivities of the pure expanded graphite BP is well reserved in the composite BPs under high molding pressure, which can facilitate the heat transfer and electron conduction in the PEMFCs. The relative density and compressive strength of composite BPs were greatly enhanced by the impregnation of resin compared to the expanded graphite under high molding pressure without the impregnation of resin (HU-BP). The maximum thermal conductivity, compressive strength, and minimum interfacial contact resistance (ICR) are collectively achieved in the HL-BP. The enhanced thermal-electrical and mechanical properties could be mainly attributed to the well-reserved continuous networks of graphite in the composite BPs. The findings in this paper are expected to synergetically improve the thermal, electrical, and mechanical properties of composite BPs through coupled manipulations of the molding and impregnation pressures, which in turn enhances the power density and durability of PEMFCs.
Highlights
Proton exchange membrane fuel cells (PEMFCs) are considered one of the most competitive energy-utilization devices for carbon emission reduction because of their high power density, low operating temperature, and pollution-free reaction products
The cross-section morphology of channel-rib in the graphene-resin composite bipolar plate (BP) is investigated to evaluate the effect of molding and impregnation pressure on the evolution of composite microstructure
The corresponding energy disperses spectroscopy (EDS) map on the right side of Figure 2a shows that the element in the HU-BBP is almost carbon with invisible oxygen concentration, indicating that the impurities in the expanded graphite were significantly removed during the high-temperature pyrolysis process
Summary
Proton exchange membrane fuel cells (PEMFCs) are considered one of the most competitive energy-utilization devices for carbon emission reduction because of their high power density, low operating temperature, and pollution-free reaction products. There is great potential to improve PEMFC performance and durability through enhancing the performance of BPs. The specific function of BPs in the PEMFC stack can be described as follows: the reactant gas is fed in and distributed in the cell through the flow field pressed in the BPs [4,5]. The electrons generated in the reaction are conducted to the external circuit via the BPs. the BP functions can be enhanced from two aspects, one is the electron/heat conduction (material selection), and another is gas/liquid transport (flow field structure design). The electrical and thermal conductivities, mechanical strength, and corrosion resistance of BP are mainly determined by the material, while the reactant gas diffusion and resultant liquid water transport capacities are controlled by the flow field structure
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