Preparation, characterization and cell performance of durable nafion/SiO_2 hybrid membrane for high-temperature polymeric fuel cells

摘要

The Nafion 117 membrane has doped with SiO_2 particles by in situ sol-gel reaction. In order to minimize leaching of doped particles, the reaction conditions are optimized using full factorial design of experiment. The results obtained from the full factorial analysis indicate that the minimum amount of leaching takes place at 60 ℃, without addition of acid, and with the swelling of membranes prior to the reaction. The membranes, prepared at optimum reaction conditions, are characterized for water uptake, thermal stability, proton conductivity, and cell performance. Furthermore, Nafion/SiO_2 composites are investigated to reduce the hydrogen permeation rate across the membrane. The Nafion/SiO_2 composites demonstrate significantly low hydrogen permeability. Moreover, the water uptake of Nafion/SiO_2 membrane with 7% of doping level increase up to 43% that is 30% higher than that of the pure Nafion membrane. DSC Measurements for modified samples show an increase in Tg as compared to unmodified sample. In general, the proton conductivities of hybridized membranes under ambient temperature are lower than that of the pure membrane. However, at 110 ℃ and in low humid conditions, the modified membranes show increased fuel cell performance than the pure Nafion. Among the composite membranes, the sample with 5-7% of SiO_2 content exhibits higher water uptake and better performance of fuel cell test.