ZrO sub(2-SiO) sub(2)/Nafion[super][registered] composite membrane for polymer electrolyte membrane fuel cells operation at high temperature and low humidity

Recast Nafion[super][registered] composite membranes containing ZrO sub(2-SiO) sub(2) binary oxides with different Zr/Si ratios are investigated for polymer electrolyte membrane fuel cells (PEMFCs) at temperatures above 100 [deg]C. Fine particles of the ZrO sub(2-SiO) sub(2) binary oxides, same as an inorganic filter, are synthesized from a sodium silicate and a carbonate complex of zirconium by a sol-gel technique. The composite membranes are prepared by blending a 10% (w/w) Nafion[super][registered]-water dispersion with the inorganic compound. All composite membranes show higher water uptake than unmodified membranes, and the proton conductivity increases with increasing zirconia content at 80 [deg]C. By contrast, the proton conductivity decreases with zirconia content for the composite membranes containing binary oxides at 120 [deg]C. The composite membranes are tested in a 9-cm[super]2 commercial single cell at both 80 [deg]C and 120 [deg]C in humidified H sub(2/air under different relative humidity (RH) conditions. Composite membrane containing the ZrO) sub(2)-SiO sub(2 binary oxide (Zr/Si = 0.5) give the best performance of 610 mW cm[super]-1 under conditions of 0.6 V, 120 [deg]C, 50% RH and 2 atm.)