Poly(benzimidazole)/poly(vinylphosphonic acid) blend membranes with enhanced performance for high temperature polymer electrolyte membrane fuel cells

PBI:PVPA (Poly(benzimidazole):poly(vinylphosphonic acid)) polymer electrolyte membranes were fabricated with several molar ratios and number-average molecular weights ((M) over bar (n)) of PVPA. Inter-polymer interactions and cross-section morphology of membranes were analyzed using FT-IR and scanning electron microscopy, respectively. Water uptake, proton conductivity, and methanol permeability of the membranes were characterized at several operating conditions. In addition, the influence of doping level of phosphoric acid (H3PO4) on the membranes proton conductivity was investigated. The membranes proton conductivities were enhanced with PVPA molar ratio and (M) over bar (n). The highest proton conductivity at 150 degrees C, 79.6 mS.cm(-1), was obtained for H3PO4-doped PBI:PVPA membrane containing PVPA with (M) over bar (n) of 42,000 g.mol(-1), PBI:PVPA molar ratio of 1:1 and H3PO4 doping level of 15.2. Proton hopping between PBI and PVPA was found to be the most dominant proton transport mechanism through the PBI:PVPA membranes, especially at anhydrous state. Finally, the results suggest that these membranes are promising candidates for high-temperature proton exchange membrane fuel cell applications.

Automated summary

The PBI:PVPA polymer electrolyte membranes were fabricated and characterized for proton conductivity at high temperatures. The results indicate that these membranes have promising potential for high-temperature proton exchange membrane fuel cell applications.