Development of hybrid proton exchange membrane based on Nafion and sulfonated FEP prepared by EB-irradiation

Proton exchange membranes (PEMs) are the key components of polymer electrolyte fuel cells (PEFCs). Perfluorinated membranes such as Nafion (DuPont) are used as PEMs predominantly due to their chemical stability, however, the cost of Nafion is still very high. In our previous studies, cost-competitive and high performance PEMs for PEFCs were prepared by radiation induced grafting method. However, it is considered that poor interface properties between the obtained PEM and electrodes induce high interfacial resistance in PEFC. In this study, hybrid PEMs (FNs) were fabricated grafted membrane (s-FEP) with ionomer (Nafion dispersion) which was applied to coat the interface of the PEM and electrodes. The obtained FNs, sulfonated FEP and Nafion 112 were characterized in terms of water uptake, ion exchange capacity (IEC), polarization performance and electrochemical impedance spectroscopy. FNs showed high IEC and water uptake, which would induce the highest ionic conductivity (IC) among tested PEMs. In terms of FNs, the interface between the PEM and electrodes should have been improved because FNs showed the lowest charge transfer resistance among tested PEMs. The high IC and improved interface between the hybrid PEM and electrodes resulted in the best cell performance of FN among tested PEMs. (Author)