Designing Flexible Carbon Nanofiber Membranes by Electrospinning and Cross-Linking for Proton Exchange Membrane Fuel Cells

Traditional carbon-based materials suffer from fragility, low mechanical strength, and electrical conductivity when they are used as a gas diffusion layer (GDL) in proton exchange membrane fuel cells (PEMFCs), resulting in low power density. In this study, a flexible carbon nanofiber membrane (CFM) was studied for use as a GDL, prepared by polyacrylonitrile (PAN) electrospinning with the incorporation of carboxylated multiwalled carbon nanotubes (MWCNTs), polyethylenimine (PEI) impregnation, glutaraldehyde (GA) cross-linking, and thermal treatment. The concentrations of MWCNTs in the electrospinning solution and PEI in the impregnation solution were investigated. Interestingly, the mechanical strength and electrical conductivity of CFM showed a triangle trend with the MWCNTs or PEI concentration. The optimal sample (CNT1.5/PEI7/GA-CFM) demonstrated good flexibility, with an in-plane resistivity of 18.60 mΩ cm, a tensile strength of 7.94 MPa, and a bending strength of 20.65 MPa. The peak power density and maximum current density were respectively 1169 mW cm –2 and 2720 mA cm –2, exceeding those of commercial Toray and Cetech GDLs under identical testing conditions. These results illustrate the potential of high-performance electrospun CFMs for GDL applications.