High performance aliphatic-heterocyclic benzyl-quaternary ammonium radiation-grafted anion-exchange membranes
High performance aliphatic-heterocyclic benzyl-quaternary ammonium radiation-grafted anion-exchange membranes
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DOI：
10.1039/c6ee01958g
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发表时间：
2016-01-01
影响因子：
32.5
通讯作者：
Varcoe, John R.
中科院分区：
文献类型：
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作者：
Ponce-Gonzalez, Julia;Whelligan, Daniel K.;Varcoe, John R.
报道了用辐射接枝法在聚乙烯-共四氟乙烯（ETFE）薄膜上合成了含饱和杂环苄基季铵（QA）基团的阴离子交换膜（AEM）。并与辐射接枝etfe -g-聚乙烯苄基三甲基铵AEM进行了比较。两种含有杂环qa头基团的AEMs在80℃（与基准相比）的KOH水溶液（1 mol dm(-3)）中具有较高的相对稳定性：这些100 mm厚（完全水合）ETFE-g-poly（乙烯基苄基- n-甲基哌啶）和ETFE-g-poly（乙烯基苄基- n-甲基吡啶）基AEM的离子交换容量（IEC）分别为1.64和1.66 mmol g(-1)，碱老化后降低到1.36 mmol dm(-3)（约17-18%的IEC损失）（基准AEM在相同条件下的IEC损失为30%）。这些下选择的AEMs在90℃和95%相对湿度环境下的Cl-离子电导率分别为49和52 mS cm(-1)，而OH-在80℃和95%相对湿度环境下的电导率分别为138和159 mS cm（-1）。ETFE-g-poly（乙烯基苄基- n -甲基吡咯吡啶）基AEM作为催化剂包覆膜，在60℃下以PtRu/C阳极、Pt/C阴极和聚砜离聚体在H-2/O-2碱性聚合物电解质燃料电池中测试时，获得了最高的性能。100亩厚的变体（由50亩厚的ETFE合成）产生的峰值功率密度分别为800和630兆瓦厘米（-2）（分别有和没有0.1 MPa背压），而52亩厚的变体（由25亩厚的ETFE合成）在相同条件下产生980和800兆瓦厘米（-2）。根据这些结果，我们建议AEMs的开发人员，特别是悬垂的苄基- qa类型，应该考虑将苄基- n -甲基吡啶基作为目前事实上的基准苄基三甲铵头基的改进。
Anion-exchange membranes (AEM) containing saturated-heterocyclic benzyl-quaternary ammonium (QA) groups synthesised by radiation-grafting onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films are reported. The relative properties of these AEMs are compared with the benchmark radiation-grafted ETFE-g-poly(vinylbenzyltrimethylammonium) AEM. Two AEMs containing heterocyclic-QA head groups were down-selected with higher relative stabilities in aqueous KOH (1 mol dm(-3)) at 80 degrees C (compared to the benchmark): these 100 mm thick (fully hydrated) ETFE-g-poly(vinylbenzyl-N-methylpiperidinium)- and ETFE-g-poly(vinylbenzyl-N-methylpyrrolidinium)-based AEMs had as-synthesised ion-exchange capacities (IEC) of 1.64 and 1.66 mmol g(-1), respectively, which reduced to 1.36 mmol dm(-3) (ca. 17-18% loss of IEC) after alkali ageing (the benchmark AEM showed 30% loss of IEC under the same conditions). These down-selected AEMs exhibited as-synthesised Cl- ion conductivities of 49 and 52 mS cm(-1), respectively, at 90 degrees C in a 95% relative humidity atmosphere, while the OH- forms exhibited conductivities of 138 and 159 mS cm(-1), respectively, at 80 degrees C in a 95% relative humidity atmosphere. The ETFE-g-poly(vinylbenzyl-N-methylpyrrolidinium)-based AEM produced the highest performances when tested as catalyst coated membranes in H-2/O-2 alkaline polymer electrolyte fuel cells at 60 degrees C with PtRu/C anodes, Pt/C cathodes, and a polysulfone ionomer: the 100 mu m thick variant (synthesised from 50 mu m thick ETFE) yielded peak power densities of 800 and 630 mW cm(-2) (with and without 0.1 MPa back pressurisation, respectively), while a 52 mu m thick variant (synthesised from 25 mu m thick ETFE) yielded 980 and 800 mW cm(-2) under the same conditions. From these results, we make the recommendation that developers of AEMs, especially pendent benzyl-QA types, should consider the benzyl-N-methylpyrrolidinium head-group as an improvement to the current de facto benchmark benzyltrimethylammonium head-group.