Imidazolium-functionalized anion exchange membranes using poly(ether sulfone)s as macrocrosslinkers for fuel cells

A series of novel macrocrosslinked imidazolium-based anion exchange membranes (AEMs) with high hydroxide conductivity and dimensional stability were synthesized by crosslinking a poly(vinyl imidazole) ionic liquid with bromide-terminated poly(ether sulfone) via Menshutkin reaction. Fourier transform infrared (FT-IR) and energy dispersive spectrometry (EDS) were used to confirm the chemical structure and successful crosslinking of the AEMs. The contiguous imidazolium cations along the polyolefin backbone are found to aggregate and connect to form continuous hydroxide transport microchannels by the introduction of long hydrophobic poly(ether sulfone) chain as evidenced by atomic force microscopy (AFM). As a consequence, a high hydroxide conductivity of 78.5 mS cm(-1) was achieved for the crosslinked PES/PVIIL-0.4 membrane at 80 degrees C. A single cell test using the PES/PVIIL-0.4 membrane exhibits an open circuit voltage of 1.039 V and peak power density of 109.5 mW cm(-2) at the current density of 190 mA cm(-2) at 60 degrees C. This newly developed strategy holds great promise to prevent fuel crossover in alkaline fuel cells.