Conventional proton exchange membrane fuel cells (PEMFCs) operate within narrow temperature ranges. Typically, they are run at either 80‒90 °C using fully humidified perfluorosulfonic acid membranes, or at 140‒180 °C using non-humidified phosphoric acid (PA)-doped membranes, to avoid water condensation-induced PA leaching. However, the ability to function over a broader range of temperature and humidity could simplify heat and water management, thus reducing costs. Here we present PA-doped intrinsically ultramicroporous membranes constructed from rigid, high free volume, Tröger’s base-derived polymers, which allow operation from −20 to 200 °C. Membranes with an average ultramicropore radius of 3.3 Å show a syphoning effect that allows high retention of PA even under highly humidified conditions and present more than three orders of magnitude higher proton conductivity retention than conventional dense PA-doped polybenzimidazole membranes. The resulting PA-doped PEMFCs display 95% peak power density retention after 150 start-up/shut-down cycles at 15 °C and can accomplish over 100 cycles, even at −20 °C.
High-performance gas separation membranes have potential in industrial separation applications, while overcoming the permeability-selectivity trade-off via regulable aperture distribution remains challenging. Here, we report a strategy to fabricate Polyolefin Reweaved Ultra-micropore Membrane (PRUM) to acquire regulable microporous channel. Specifically, olefin monomers are dispersed uniformly into a pristine membrane (e.g., PIM-1) via solution diffusion method. Upon controlled electron beam irradiation, the olefin undergoes a free radical polymerization, resulting in the formation of olefin polymer in-situ reweaved in the membrane. The deliberately regulated and contracted pore-aperture size of the membrane can be accomplished by varying the olefin polymer loading to achieve efficient gas separation. For instance, PIM-1 PRUM containing 27 wt% poly-glycidyl methacrylate demonstrate CO 2 permeability of 1976 Barrer, combined with CO 2 /CH 4 and CO 2 /N 2 selectivities of 58.4 and 48.3 respectively, transcending the performance upper bounds. This controllable and high efficiency-design strategy provides a general approach to create sub-nanometre-sized pore-apertures of gas separation membranes with wide universality.
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