Fuel Cell Electrolytes of Polybenzimidazole Membranes Cross‐linked with Bis(chloromethyl) Arenes.

Cross‐linking of phosphoric acid doped polybenzimidazole membranes as fuel cell electrolytes represents an attractive approach to improving the mechanical robustness at a high acid loading. Numerous cross‐linking concepts have been reported in the literature, but a deeper understanding of how the cross‐linking chemistry affects the physicochemical properties of the membrane and its fuel cell performance and durability remains to be assessed. In this work, a series of cross‐linked membranes are prepared using cross‐linking agents of different regio‐chemistry and steric nature. It is shown, that the nature of the cross‐linking agent has a large impact on the effective degree of cross‐linking, which in turn determines the acid doping characteristics and ultimately the fuel cell performance and acid retention during long‐term operation. [ABSTRACT FROM AUTHOR]