Anion-exchange membranes for alkaline polymer electrolyte fuel cells: comparison of pendent benzyltrimethylammonium- and benzylmethylimidazolium-head-groups
Anion-exchange membranes for alkaline polymer electrolyte fuel cells: comparison of pendent benzyltrimethylammonium- and benzylmethylimidazolium-head-groups
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DOI：
10.1039/c2ee22466f
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发表时间：
2012-09-01
影响因子：
32.5
通讯作者：
Varcoe, John R.
中科院分区：
文献类型：
--
作者：
Deavin, Oliver I.;Murphy, Sam;Varcoe, John R.
从相同的基膜和具有相同的离子交换容量的辐射接枝碱性阴离子交换膜（AAEM）成功地合成了含有侧基的苄基三甲基铵（BTM）或苄基甲基咪唑（BMI）功能。新BMI-AAEM的电导率与BTM基准AAEM相当。然而，由于原位AAEM降解，用BMI-AAEM获得的燃料电池性能明显较差。FT-拉曼光谱研究表明，在60 ℃下，在氢氧化钾水溶液（1 mol dm（-3））中，两个头基的稳定性表明，BMI基团在强碱性条件下的化学稳定性比BTM基准头基低。然而，当在60 ℃下在较低pH的碳酸盐和碳酸氢盐水溶液（1 mol dm（-3））中处理时，两个头基的稳定性得到改善。与部分现有文献相反，在高碱性体系中使用含有咪唑鎓侧基的阴离子交换聚合物电解质似乎没有真实的优点。
Radiation-grafted alkaline anion-exchange membranes (AAEM) containing pendent groups with either benzyltrimethylammonium (BTM) or benzylmethylimidazolium (BMI) functionality were successfully synthesised from the same base membrane and with identical ion-exchange capacities. The conductivity of the new BMI-AAEM is comparable to the BTM-benchmark AAEM. The fuel cell performance obtained with the BMI-AAEM was, however, significantly poorer due to in situ AAEM degradation. FT-Raman spectroscopic studies on the stability of the two head-groups at 60 degrees C in aqueous potassium hydroxide (1 mol dm(-3)) indicates that the BMI-group is intrinsically less chemically stable in strongly alkaline conditions compared to the BTM-benchmark head-group. However, the stabilities of both head-groups are improved when treated at 60 degrees C in lower pH aqueous carbonate and bicarbonate solutions (1 mol dm(-3)). Contrary to a portion of the prior literature, there appears to be no real advantage in using anion-exchange polymer electrolytes containing pendent imidazolium groups in highly alkaline systems.