Hierarchical structures and fuel cell properties of imidazolium-containing anion conducting polymer electrolyte membranes prepared by radiation-induced grafting

Yoshimura, Kimio; Zhao, Y.; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Koizumi, Satoshi*; Maekawa, Yasunari

Anion conducting polymer electrolyte membranes (AEMs) having poly 2-methyl-1-vinylimidazolium grafts were synthesized by radiation-induced graft coplymerizaiton of 2-methyl-1-vinylimidazole with styrene onto an ETFE film, followed by N-alkylation and ion exchange reactions. The excellent long-term stability of the prepared AEMs was confirmed in 1M KOH at 80C. The graft-type AEM with an ion exchange capacity of 1.80 mmol/g showed a maximum power density of 210 mW cm in a direct hydrazine hydrate fuel cell test. The contrast variation experiment in small-angle neutron scattering measurement displayed the advantageous three-phase structures, consisting of crystalline, amorphous hydrophobic, and amorphous hydrophilic domains.