A reinforced composite membrane of two-layered asymmetric structure with Nafion ionomer and polyethylene substrate for improving proton exchange membrane fuel cell performance

The reinforced composite membrane with a two-layered asymmetric structure was fabricated by impregnating the Nafion on a porous polyethylene (PE) substrate to reduce the cost of the membrane used in proton exchange membrane fuel cells (PEMFCs) as well as to enhance the performance of the cell. The ion conductivity of the reinforced composite membrane annealed at 150 degrees C increases owing to the high crystallinity of the Nafion ionomer, and the mechanical strength is improved by the strong interaction between PE substrate and Nafion ionomer. The immiscibility between them was observed to intensify the interfacial resistance in the three-layered symmetric structure. On the other hand, the reduction of the interfacial resistance of the two-layered asymmetric structure membrane leads to similar results to the performance of traditional PEMFC using Nafion XL with a polytetrafluoroethylene (PTFE) substrate similar to a backbone of Nafion ionomer. Its high mechanical strength, low cost, and reliable ion conductivity make it a suitable substitute for PTFE-based membranes used in PEMFCs although the immiscibility with the ionomer in the membrane comprising a PE substrate is higher than that in the membrane with a PTFE substrate.