Cross-linked Anion Exchange Membranes Composed of Imidazolium Salt for Alkaline Fuel Cell

The alkaline membrane fuel cells (AMFCs), which use the anion-exchange membranes(AEMs) as electrolytes have attracted considerable attention owing to their higher reaction kinetics, lower fuel crossover, reduced CO poisoning, and use of non-precious metal catalysts. ¹ In the development of AMFCs, the AEMs are obviously the key issues to make a breakthrough in AMFC performances. However, the conductivity and stability of AAEMs are still far less than commercial membrane Nafion which has commonly been used to proton-exchange membrane fuel cells (PEMFCs).²

More recently, imidazolium-based AEMs are of interest due to the five-membered heterocyclic ring and π conjugated structure of the imidazolium cation, which is expected to have good stability in alkaline condition.^3-4 We here report novel series of alkaline anion-exchange membranes: Chitosan / poly (3-methyl-1-vinylimidazolium chloride)-Co-(1-vinylpyrrolidone) membranes (Cs/PMViC-Co-VP)and PVA/ poly (3-methyl-1-vinylimidazolium chloride)-Co-(1-vinylpyrrolidone) (PVA/PMViC-Co-VP)membranes.

The membranes were prepared by a solution-casting method, where 1g chitosan (degree of deacetylation = 80.0-95.0,supplied by Sinopharm Chemical Reagent Co. Ltd. China) was dissolved in 50 mL of 2% aqueous solution of acetic acid. Meanwhile, PVA (99% hydrolyzed, average molecular weight M_w = 86,000-89,000; Aldrich) was fully dissolved in water to make a 10% solution at 70^oC. Then PMViC-Co-VP (supplied by Aldrich) was mixed with the above chitosan solution and PVA solution, respectively. At last, 0.5 mg GA was added in two types of composite solutions for cross-linking reaction. Membranes were obtained with a thickness about 50-120 µm. The The hydroxyl ion conductivity of the obtained membrane is studied using AC impedance technique.