Novel cross-linked PBI-blended membranes evaluated for high temperature fuel cell application and SO2 electrolysis

Within this study various partially fluorinated polyaromatic and PBI blend components were covalent-ionically cross-linked to obtain acid and base-excess proton exchange membranes that can be applied in high temperature fuel cells and SO2 electrolysis. A stability assessment of the blend membranes included an extraction experiment in the organic solvent N, N-dimethylacetamide (DMAc), Fenton's Test (FT) and an 80 wt% H2SO4 treatment for 120 hours at 100 degrees C. Furthermore the thermal stability of the materials were evaluated by TGA-FTIR coupling, and the H+-conductivity determined for the phosphoric acid-doped (PA) membranes in temperature ranges 60-140 degrees C. It was found that all blend membranes showed good chemical stability during the H2SO4 treatment; though the base-excess blend membranes reported better chemical stabilities in the FT and DMAc extraction experiments in comparison to the acid-excess blends. The earliest thermal degradation for a blend membrane was found to start at 277 degrees C, only after the H2SO4 treatment, supporting the thermal stability. For the PA-doped blend membranes conductivities of 39,6 mS/cm reported at 140 degrees C was comparable to earlier work on similar membrane blends, but now achieved at a lower PA-doping level. Furthermore the base-excess membrane selected for fuel cell (FC) testing reported comparable in the polarization curves recorded at 140 degrees C, however a maximum power density of 88.2 mW/cm(2) was reached in comparison to the 72.8 mW/cm(2) of Celtec (R)-P under the same operation conditions for similarly prepared MEAs. This all proves promising for further testing and optimization of the blend membranes for HTFC and SO2 electrolysis applications. (C) 2017 Elsevier Ltd. All rights reserved.