Blend Membranes Based on Acid-Base Interactions for Operation at High Methanol Concentrations

The performances in direct methanol fuel cells (DMFCs) of membrane electrode assemblies (MEAs) fabricated with blend membranes based on sulfonated poly(ether ether ketone) (SPEEK) and poly(sulfone) bearing 2-amino-benzimidazole have been compared with SPEEK and Nafion ionomers in the anode and cathode catalyst layers as well as with that of MEAs fabricated with Nafion 115 membrane and Nafion ionomer in the electrodes. The SPEEK ionomer offers better compatibility with a lower interfacial resistance compared to Nafion ionomer when used with the blend membranes. Also, MEAs fabricated with the blend membrane and SPEEK ionomer in the electrodes exhibit better performance in DMFC compared to that with Nafion membrane and Nafion ionomer due to lower methanol crossover. Moreover, MEAs fabricated with the blend membranes exhibit less performance dependence on methanol concentration (1-10 M) compared to those fabricated with the Nafion membranes, making the former attractive to operate at high methanol-feed concentrations.