P(VDF-TrFE) reinforced composite membranes fabricated via sol-gel and dual-fiber electrospinning for reduced relative humidity operation of PEM fuel cells

Official URL: https://dx.doi.org/10.1016/j.ssi.2023.116152

In this study, dual-fiber electrospinning and sol-gel methods have been used to prepare membranes for low relative humidity conditions, with low dimensional change containing poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)), Nafion® and hygroscopic sulfonated-silica (S-SiO2) additive. This approach allowed us to finely tune the polymer ratios, additive contents, and ultimate homogeneous distribution to provide better water uptake, proton conductivity, and robustness. In this study, for the first time, S-SiO2 was synthesized using 3-(trihydroxysilyl) -1-propanesulfonic acid (TPS) and tetraethyl orthosilicate (TEOS) via the sol-gel method for the PEM fuel cell application at low humidity. We characterized our membranes in terms of morphology, ion exchange capacity, ionic conductivity, molecular structure, mechanical properties, hydrogen crossover, and fuel cell performance. To investigate the effect of reinforcing polymer, the results obtained from P(VDF-TrFE)-based membranes were compared with polyvinylidene fluoride (PVDF)-based membranes. Although Young's modules of PVDF-based membranes (324 MPa) are higher compared to the P(VDF-TrFE)-based membranes (228 MPa), the latter showed greater proton conductivity (132 mS/cm) and fuel cell performance, particularly at low RH conditions. Furthermore, P(VDF-TrFE)-based membranes provided a maximum power density of 344 mW/cm2 which is almost 2-times higher than that of PVDF-based membranes.