Influence of doping level in Yttria-Stabilised-Zirconia (YSZ) based-fillers as degradation inhibitors for Proton Exchange Membranes Fuel Cells (PEMFCs) in drastic conditions

Yttria-Stabilized-Zirconia fillers with different Y2O3 loadings are used to prepare composite Nafion membranes for PEMFCs. XRD and BET demonstrate the formation of a c-ZrO2 mesoporous structure. SEM reveals a size reduction of the agglomerates increasing the ZrO2 doping level. A good mechanical resistance, no variation into the water retention, swelling restraint and an increased Ion Exchange Capacity (IEC) of the membranes are found respect to reference membrane, above all for highly doped membranes, indicating an acidic properties enhancement. Proton conductivity (PC) at 100%RH (80-100°C) is unchanged for composite membranes compared to reference. At 75%RH, PC is positively affected by the highest YSZ loadings. Fenton's test on membranes evidences a higher oxidative chemical stability for composite membranes. This improved stability is confirmed by accelerated stress test in drastic conditions: composite highly doped membranes work for more than 110 cycles with a good performance and lower H2-crossover against 95 cycles and higher H2-crossover than reference membrane.