Tröger’s base-based cross-linker for suppressing acid leaching and enhancing durability of high-temperature polymer electrolyte membranes

A series of high-temperature polymer electrolyte membranes (HT-PEMs) materials was successfully fabricated by cross-linking ether-bonded polybenzimidazole (OPBI) with a functionalized Tröger's base (TB) moiety. Additionally, the unique pore structure of the TB group endows it with outstanding phosphoric acid (PA) adsorption properties, significantly enhancing its PA absorption capacity and long-term retention capability. Despite 240 h of continuous operation under the harsh conditions of 160 °C/0% RH, the PA retention rate of the membrane remains above 80%. Benefiting from the dense and rigid cross-linked network constructed by the cross-linker, the membranes can still maintain a mechanical strength of over 7.9 MPa after PA doping. Simultaneously, the dense crosslinked structure endows the membrane material with outstanding resistance to strong oxidizing radicals. After 144 h of treatment in a 4 ppm Fenton solution, the OPBI-TB-15 performance retention rate reaches 84.8%. In a single-cell test, the OPBI-TB-15 a peak power density of 857.8 mW cm -2 at 180 °C. The results above fully demonstrate that the OPBI-TB-X membrane material incorporating TB groups exhibits outstanding acid retention, mechanical stability, and oxidation resistance. Consequently, it shows broad application prospects in the field of high-temperature polymer electrolyte membranes fuel cells (HT-PEMFCs).