Sulfonated poly(arylene ether sulfone)/functionalized silicate hybrid proton conductors for high-temperature proton exchange membrane fuel cells

An approach for improving the proton exchange membrane fuel cell (PEMFC) membrane's transport properties in sulfonated poly(arylene ether sulfone) copolymers (SPAES) has been demonstrated, which is based on in situ hybridization of a functionalized silane material, 3-(trihydroxylsilyl)propane-1-sulfonic acid (AS). Functionalized silicates with sulfonic acid groups are produced in the membrane during casting procedure. Those functionalized silicates provide additional proton conducting moieties to the membrane. The functionalized silicate content affects the morphology, dimensional stability, fuel cell performance, and fuel crossover of the hybrid membranes. Its effects are quantitatively identified. The ion exchange capacity (IEC) and transport properties are discussed to provide an in-depth understanding of the proton conductivity enhancement at various temperatures and humidity conditions. A noteworthy observation is that the incorporation of AS in SPAES is effective in suppressing the hydrogen crossover while increasing proton conductivity resulting in higher PEMFC performance, even though water uptake decreased as AS content increased.

► Hybrid membrane for high temperature PEMFCs has been synthesized.
► 3-(Trihydroxylsilyl)propane-1-sulfonic acid was incorporated into SPAES-50.
► Performance (120 °C, 50% R.H.) improved by nearly 100% (@0.6 V) compared to pristine membranes.
► Fuel crossover was reduced by 80% (120 °C, 50% R.H.).