Cross-Linked Alkaline Ionic Liquid-Based Polymer Electrolytes for Alkaline Fuel Cell Applications

We report an effective and simplified procedure for the synthesis of cross-linked alkaline anion-exchange membranes (AEMs). AEMs based on alkaline imidazolium-type ionic liquids (ILs) were prepared via in situ cross-linking of 1-vinyl-3-methylimidazolium iodide ([VMIm][I]) with styrene and acrylonitrile, and followed by anion-exchange with hydroxide ions. The resulting cross-linked copolymer membranes exhibit high hydroxide ion conductivity (above 10(-2) S/cm at room temperature) and good mechanical properties. The thermal stability of the produced AEMs is comparable to that of quaternary ammonia aromatic polymers. The membranes display an excellent chemical stability up to 400 h in high pH solution without an obvious loss of ion conductivity and mechanical properties. This synthetic procedure avoids the use of chloromethyl methyl ether and solution casting generally used for AEMs preparation. The results of the study suggest a feasible approach for the synthesis and practical applications of alkaline AEMs and are expected to promote the widespread use of alkaline fuel cells.