Synthesis and characterization of novel anion exchange membranes containing bi-imidazolium-based ionic liquid for alkaline fuel cells

• Anion exchange membranes containing bi-imidazolium ionic liquid were synthesized.
• The membrane shows the conductivity at 80 °C up to 41.9 mS cm− 1.
• The membrane keeps better long-term stability in 1 M KOH methanol solution.
• Long alkyl side chain drives the N+ site to aggregate and promoting OH− mobility.

Novel anion-exchange membranes (AEMs) were prepared via in situ assembly of N-dodecyl-imidazole and 1,4-dibromobutane to construct the bi-imidazolium functionalized cationic liquid monomer, butanediyl-1,4-bis(N-dodecylimidazole bromide) into the isopropanol dispersions of quaternized chitosan, and followed by anion exchange with OH−. The morphology and characteristic properties of the resultant membranes, such as ion exchange capacity (IEC), anionic conductivity, and chemical stability were investigated. The membrane containing 15% mass fraction of butanediyl-1, 4-bis(N-dodecylimidazole bromide) shows that the anionic conductivity at 80 °C up to 41.9 mS cm− 1 and keep better long-term stability for 300 h in 1 mol dm− 3 KOH methanol solution than in 1 mol dm− 3 KOH aqueous solution. The introduction of hydrophobic alkyl side chain of the imidazole rings could drive the N+ ionic clusters to aggregate and promoting OH− mobility in AEMs. The results of this study suggest that the AEMs based on bi-imidazolium cations with long alkyl side chain have good perspectives for alkaline fuel cell application.