High-stability poly(carbazole-isatin) anion exchange membranes with alkyl-alkyloxy double synergistic side chains for fuel cell application

Given that anion exchange membrane fuel cells are a viable alternative approach to minimize fuel cell costs, but their ion conductivity is naturally lessened than that of proton exchange membrane and the problems of low stability still confine their practical application. Here, two kinds of carbazole and isatin units are designed and incorporated in a new poly(carbazole-isatin) ionomer structure xBHC-CEOI-pip (x = 4, 6, 8) with hydrophobic alkyl-hydrophilic alkoxy double synergistic side chains. Further investigations show that the membrane 6BHCCEOI-pip reveals a high conductivity of 161.36 mS cm- 1 (80 degrees C) and a good dimensional stability (17.07% swelling at 80 degrees C). The alkali stability shows outstanding performance as well, the conductivity still retains the initial 89.95% after aging for 1512 h (2 M NaOH, 80 degrees C). In addition, 6BHC-CEOI-pip with a current density of 1120 mA cm- 2, reaches the maximum peak power density of 460 mW cm- 2 at 60 degrees C under 60 KPa back pressure. Overall, the considerable comprehensive properties of 6BHC-CEOI-pip suggests a promising fuel cell application prospects.