Imidazolium-based organic-inorganic hybrid anion exchange membranes for fuel cell applications

Imidazolium-based ionic liquids and imidazolium-based organic-inorganic hybrid alkaline anion exchange membranes (AEMs) are synthesized and investigated in the present work. The imidazolium-based hybrid AEMs are prepared via in situ cross-linking of styrene, acrylonitrile, 1-vinyl-propyl-triethoxysilaneimidazolium chloride ([VPSIm][Cl]) and 1-vinyl-3-butylimidazolium bromide ([VBIm][Br]), followed by anion exchange with hydroxide ions. The water uptake and swelling degree of the hybrid AEMs decrease with increasing [VPSIm][Cl] content due to the formation of an Si-O-Si inorganic network in the membranes. The resulting organic-inorganic hybrid AEMs show good thermal stability, excellent mechanical properties and high conductivity (above 10^-2 S cm^-1 at room temperature in liquid water). Compared with samples without the addition of [VPSIm][Cl], the hybrid membranes show much higher alkaline stability, and the hybrid AEMs displayed excellent chemical stability up to 480 h in 2 M KOH solution at 60 °C.