New ionic liquid-based polyoxadiazole electrolytes for hydrogen middle- and high-temperature fuel cells

Abstract New polyoxadiazole-based supported ionic liquid membranes were designed and elaborated for the first time to be used as a middle- and high-temperature polymer electrolyte membrane for fuel cell application. The proposed membrane molecular design combined hydroxyl-functionalized sulfonated polyoxadiazole, hydrophilic polyvinylpyrrolidone and specific protic ionic liquid, thus allowing elaboration of membranes with remarkable physical-chemical characteristics. It is found that the fine tuning of the membranes properties is possible by varying the ratio of polyoxadiazole and polyvinylpyrrolidone. The obtained membranes reveal high thermal stability in dynamic and static modes (up to 350 °C), good oxidative stability, sufficient mechanical properties (Young's modulus of 0.3–21.4 MPa and elongation at break from of 6 to 174%), high degree of ionic liquid impregnation (up to 297%), stable and relatively high conductivity (up to 1.3 mS∙cm−1) in a wide temperature range (from 40 to 120 °С) and under dry conditions. All these properties make the elaborated membranes very attractive for middle- and high-temperature fuel cell application.