Proton Transport in Aluminum-Substituted Mesoporous Silica Channel-Embedded High-Temperature Anhydrous Proton-Exchange Membrane Fuel Cells

Polymer composite membrane technology is promising for enhancing the performance of membrane electrode assemblies for high-temperature fuel cells. In this study, we developed a novel anhydrous proton-exchange polybenzimidazole ( m -PBI) composite membrane using Al-substituted mesoporous silica (Al-MCM-41) as a proton-carrier support. The surface-substituted Al-MCM-41 formed effective proton-transport pathways via its periodic hexagonal channel and improved the proton conductivity. The proton conductivity of an m -PBI filled with 9 wt.% filler was 0.356 S cm -1 at 160 °C and 0% humidity, representing an increase of 342% compared to that of a pristine m -PBI. Further, the current density at 0.6 V and maximum power density of m -PBI composite membranes were increased to 0.393 A cm -2 and 0.516 W cm -2 , respectively. The enhanced fuel-cell performance was attributed to the proton-transfer channels and H 3 PO 4 reservoirs formed by the mesopores of the Al-MCM-41 shell. The results indicated that Al-MCM-41 is suitable with respect to the hybrid homologues for enhancing the proton transport of the m -PBI membrane.