An imidazole-philic dispersible ionic liquid provides ample proton transport channels and high proton performances for high temperature proton exchange membranes

Abundant proton transport channels in polybenzimidazole proton exchange membranes (PBI-PEMs) has been considered as the guarantee of high electrochemical performances for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Porous structures are widely employed to create the channels. However, low mechanical properties of membranes results from chaotic aggregated pores hinders the application. In this study, the membrane of continuous micro-porous structure was innovatively fabricated via self-assembly of 1-Allyl-3-methylimidazolium chloride ([AmIm]Cl) in PBIs. The ionic liquid (IL) form continuous phases among PBI chains with inter-molecular distances less than 5 Å. The uniform porous structure enables tighter segment packing of polymer, creating uninterrupted PA channels that significantly enhanced proton transport efficiency without undermining the mechanical properties. The resulting micro-porous membrane displayed exceptional power density of 717.7 mW cm−2 at 160 °C, with 0.6 mg cm−2 Pt loading, accompanied by remarkable tensile strength of 12.4 MPa. Moreover, the catalyst layer exhibited superior oxygen diffusivity by optimizing the PA uptake. These results indicate that the micro-porous structure driven by the imidazole-philic dispersible ionic liquid is an effective strategy for designing high-performance PEMs.