Triblock SEBS/DVB crosslinked and sulfonated membranes: Fuel cell performance and conductivity

Abstract

AbstractA set of styrene‐ethylene‐butylene‐styrene triblock copolymer (SEBS) membranes with 10 or 25 wt% divinyl‐benzene (DVB) as a crosslinking agent were prepared and validated. Physicochemical characterization revealed suitable hydrolytic and thermal stability of photo‐crosslinked membranes containing 25 wt% DVB and post‐sulfonated. These compositions were evaluated in H2/O2 single cells, and electrical and proton conductivities were furtherly assessed. The membranes with the milder post‐sulfonation showed greater proton conductivity than those with excessive sulfonation. In terms of electrical conductivity, a universal power law was applied, and the values obtained were low enough for being used as polyelectrolytes. At the analyzed temperatures, the charge transport process follows a long‐range pathway or vehicular model. Finally, fuel cell performance revealed the best behavior for the membrane with 25 wt% DVB, photo‐crosslinked during 30 min and mild sulfonated, with a promising power density of 526 mW·cm−2. Overall, the results obtained highlight the promising fuel cell performance of these cost‐effective triblock copolymer‐based membranes and indicate that higher sulfonation does not necessarily imply better power density.