Synthesis and characterization of PEFC membranes based on fluorinated-polymer-alloy using pre-soft-EB grafting method

Polymer electrolyte fuel cell (PEFC) membranes based on thin film of crosslinked perfluorinated polymer-alloys (RX-FA) have been fabricated by soft electron beam (soft-EB) grafting with styrene monomers using soft-EB irradiation under nitrogen atmosphere at room temperature (RT). The characteristic properties of styrene-grafted materials (GRX-FA) and sulfonated materials (SRX-FA) have been measured by differential scanning calorimetry (DSC) and FT-IR spectroscopy, ionic conductivity and so on. The glass transition temperatures (dry state) of all obtained SRX-FA were about 105 ± 1 °C, which are higher than Nafion®. The ion exchange capacities of SRX-FA have been achieved about 3.3 meq/g (dry). The ionic conductivity of obtained SRX-FA has showed about 0.17 S/cm at 60 °C with relative humidity (RH) of ∼95%. The ionic conductivities of the obtained SRX-FA were higher than that of conventional perfluoro-sulfonic acid membranes (PFSA). Fabricated membrane electrode assemblies (MEAs) based on the obtained SRX-FA have shown encouraging performance in the PEFC, compared with the conventional PFSA. The power density of obtained MEAs based on the SRX-FA was about 330–340 mW/cm2 under 500 mA/cm2 at 60 °C operation. Moreover, the maximum power densities of obtained MEAs based on the SRX-FA shows about 630 mW/cm2 at 60 °C. On the other hand, the power density at 500 mA/cm2 and maximum power density of MEA based on Nafion®112 were about 320 and 590 mW/cm2 at 60 °C. Thus, the power density of the obtained SRX-FA was higher than that of conventional PFSA.