Anionic polysulfone ionomers and membranes containing fluorenyl groups for anionic fuel cells

Poly(arylene ether sulfone) ionomers containing fluorenyl groups and functionalized with benzyltrimethylammonium groups were synthesized through polycondensation, chloromethylation, and amination reactions. The resulting polymers were characterized by 1H NMR, FT-IR and TGA. Polymer membranes were solvent cast from DMF on Teflon plates to form clear, flexible anion exchange membranes (AEMs). Carbonate anions had conductivities in the AEMs up to 63.12 mS cm−1 at 70 °C and were used in a carbonate fuel cell. The membranes were stable in 1 M carbonate solution (pH 11). However, conductivity loss was observed during soaking in 1 M hydroxide solution (pH > 14) at 50 °C. A carbonate fuel cell operating at room temperature with H2 at the anode and O2 and CO2 at the cathode had a maximum power density of 4.1 mW cm−2.