Fabrication of Sulfonated Poly (ether ether ketone)/Sulfonated Fully Aromatic Polyamide Composite Membranes for Direct Methanol Fuel Cells (DMFCs)

A proton exchange membrane with low dimensional swelling and fuel crossover plays a critical role in improving the performance of fuel cells. Here, we present a facile way to overcome the high dimensional swelling and fuel crossover issues of the sulfonated poly (ether ether ketone) (SPEEK) membranes at a high ion exchange capacity (IEC) level by incorporation of sulfonated fully aromatic polyamide (S-fa-PA). A series of the S-fa-PA/SPEEK composite membranes (S-fa-PASPs) with various amount of the S-fa-PA were prepared. The influence of the S-fa-PA on thermal stability, mechanical stability, water uptake, dimensional swelling both in water and methanol aqueous solution, proton conductivity and methanol permeability was systematically investigated and compared. The excellent dimensional stabilities both in water and methanol aqueous solution of the S-fa-PASP membranes were obtained. The almost an order of magnitude lower methanol permeability than that of Nafion 117 was obtained for the S-fa-PASP membranes, suggesting that the study provides an effective approach for promoting the practical application of the SPEEK based membranes in DMFCs.