碱性燃料电池用PFA基季铵盐类阴离子交换膜的稳定性

The stability of poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) based anion exchange membranes used for alkaline fuel cell

采用辐射接枝法将氯甲基苯乙烯(VBC)接枝到四氟乙烯-全氟烷氧基乙烯基醚共聚物(PFA)基底上并对其进行季铵化和碱性化改性制备了阴离子交换膜(PFA-g-PVBC).对制得的膜采用薄膜拉伸试验、热重(TG)、热水和热碱处理等方法考察了其机械性能、热稳定性和化学稳定性.结果表明:PFA-g-PVBC阴离子交换膜具有良好的机械性能,该膜在60℃去离子水中和室温下碱性溶液中可稳定存在,但在60℃碱性溶液中因Hofmann降解反应和直接亲核取代反应而导致其电导率下降.将该膜应用于常温"自呼吸"式碱性直接乙醇燃料电池中,30mAcm-2恒电流放电情况下,电池可一次性连续放电10h以上,累计放电时间长达30h.

Novel alkaline anion-exchange membranes were synthesized by grafting vinylbenzyl chloride onto pre-irradiated poly（tetrafluoroethylene-co-perfluoropropyl vinyl ether） film,followed by quaternization and alkalization.The mechanical stability,thermal stability and chemical stability of the anion-exchange membranes were investigated.The results show that the mechanical stability of the anion-exchange membrane is good enough for fuel cell applications.The anion-exchange membranes were stable when treated in water at 60 °C and in alkaline medium at room temperature.However,due to the direct nucleophilic substitution and Hofmann degradation,the ionic conductivity of the anion-exchange membrane is reduced when the anion-exchange membrane was treated in alkaline medium at 60 °C.Durability of 30 h for an ＂air-breathing＂ ethanol single cell at 30 mA cm-2 was obtained at room temperature with the anion-exchange membrane as the electrolyte.