A highly durable long side-chain polybenzimidazole anion exchange membrane for AEMFC

As the core component in anion exchange membrane fuel cells (AEMFCs), anion exchange membranes (AEMs) have been expected to possess high ionic conductivity, low swelling, excellent mechanical, chemical and thermal stabilities. With the goal in mind, in this study, a series of long side-chain polybenzimidazole membranes with high conductivity and chemical stability has been fabricated. Firstly, a polybenzimidazole (PBI) with high molecular weight was synthesized by 3,3′,4,4′-Biphenyltetramine and 4,4′-oxybisbenzoicacid through polycondensation reaction. Then, a long side-chain is grafted onto the PBI, resulting in a highly durable long side-chain polybenzimidazole AEMs (N-PBIs) successfully. The chemical structure of the PBI, side-chain (Sc) and N-PBI was characterized by FT-IR and 1H NMR. The IEC of N-PBI samples is 0.83–1.36 mmol g−1 and the swelling ratios of these samples are 1.20–1.50%. The OH- conductivity of N-PBI increased from 0.040 to 0.11 S/cm with the increase of temperature from room temperature to 80 °C. The N-PBI membrane demonstrated highly alkaline stability in 1 M NaOH at 80 °C for over 1000 h.