Nanofiber based hybrid sulfonated silica/P(VDF-TrFE) membranes for PEM fuel cells

In this study, novel nanofiber based-hybrid proton conducting membranes for polymer electrolyte membrane (PEM) fuel cells were fabricated via electrospinning method using sulfonated silica particles (S–SiO₂) as a functional additive. Here, poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) was used as the carrier polymer during electrospinning step for the fabrication of PEM fuel cell membrane structure for the first time in literature. The effect of electrospinning conditions, i.e. namely, solvent, carrier polymer, electrospinning voltage, relative humidity, and flow rate on the uniformity of the resultant electrospun mats, and the average fiber diameter, respectively, were investigated in detail. Furthermore, electrospinning was conducted with poly(vinylidene fluoride) (PVDF) as the carrier polymer to compare with (P(VDF-TrFE)) as well. S–SiO₂ particles were homogeneously distributed along the carrier polymer without any noticeable bead formation. After electrospinning, fiber mats were transformed into dense membranes via hot-pressing and subsequent Nafion® impregnation. After obtaining the densified membrane, proton conductivity, water uptake and mechanical strength of the hybrid membranes were examined and reported as well. Consequently, hybrid membrane with P(VDF-TrFE) carrier exhibited a superior proton conductivity (102 mS/cm) benchmarked with PVDF carrier polymer containing membrane (43 mS/cm) and solution casted Nafion® membrane (95 mS/cm) at the same conditions.