Finely Adjusted Intrinsically Microporous Copolyimide Electrolyte Membranes for Fuel Cells Operating in a Wide Temperature Range

Abstract

The development of proton exchange membrane fuel cells(PEMFCs)that operate over a wide temperature range without additional humidificationsystems remains challenging. In this work, wide-temperature-rangeproton exchange membranes (PEMs) were constructed from novel Tro''ger'sbase (TB)-based intrinsically microporous copolyimides (co-PIs) finelyadjusted by incorporating crown ether units into chain backbones.Owing to the strong siphoning effect of existing microporosity andhydrogen bonds or the acid-base interactions of crown etherand TB units with phosphoric acid (PA) and/or H2O, thePA-doped co-PI membrane electrode assemblies (MEAs) can easily operatestably from 30 to 160 degrees C under H-2/air conditions evenwithout any external humidifiers. Regarding its single-cell performance, PI-TB-N30C achieved maximum power densities of 250 and 361mW cm(-2) at 80 and 160 degrees C, respectively, underanhydrous conditions. In addition, PA-doped co-PI MEA can accomplishlong-term stable operation under low or high temperatures for 120h. The structural architectures for PEMs based on finely adjustedmicroporous co-PIs extend beyond the current capabilities of existingPEMFCs.