Journal of Membrane Science ( IF 8.4 ) Pub Date : 2023-05-16 , DOI: 10.1016/j.memsci.2023.121719
Yifan Xia , Sinu Rajappan , Dmytro Serhiichuk , Mikkel Rykær Kraglund , Jens Oluf Jensen , David Aili
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A series of poly(vinyl alcohol-co-vinyl acetal) gel electrolytes was synthesized, characterized and assessed as electrode separators in alkaline water electrolysis. The copolymers were prepared by reacting poly(vinyl alcohol) with benzaldehyde or 4-formylbenzoic acid under acidic conditions at different ratios, and visually homogenous and water-insoluble membranes were subsequently obtained by solution casting. The physicochemical characteristics in terms of electrolyte uptake, swelling behavior, and ion conductivity could be tuned by varying the degree of functionalization. At a moderate vinyl acetal content of 5%, the membrane combined mechanical robustness with ion conductivity reaching 36 mS cm−1 in 30 wt% aqueous KOH at room temperature. Current densities of up to 1000 mA cm−2 were reached with uncatalyzed Ni-foam electrodes at a cell voltage of less than 2.6 V in alkaline water electrolysis tests, while the membrane effectively prevented hydrogen crossover. Although apparent membrane degradation was observed after a few days of electrolysis operation, the strategies presented in this work to tune membrane properties are of general relevance to the field towards the development of new ion-solvating membrane systems based on more alkaline stable and robust backbone chemistries.
中文翻译:
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用于碱性水电解的聚(乙烯醇-共-乙烯醇缩醛)凝胶电解质
合成、表征和评估了一系列聚(乙烯醇-共-乙烯醇缩醛)凝胶电解质作为碱性水电解中的电极隔膜。该共聚物是通过聚(乙烯醇)与苯甲醛或 4-甲酰基苯甲酸在酸性条件下以不同比例反应制备的,随后通过溶液流延获得视觉上均匀且不溶于水的膜。可以通过改变功能化程度来调整电解质吸收、溶胀行为和离子电导率方面的物理化学特性。在 5% 的适度乙烯醇缩醛含量下,该膜结合了机械强度和室温下在 30 wt% KOH 水溶液中达到 36 mS cm -1的离子电导率。电流密度高达 1000 mA cm在碱性水电解测试中,未催化的泡沫镍电极在低于 2.6 V 的电池电压下达到-2 ,而该膜有效地防止了氢交叉。尽管在电解操作几天后观察到明显的膜降解,但这项工作中提出的调整膜特性的策略与开发基于更碱稳定和稳健的主链化学的新型离子溶剂化膜系统的领域具有普遍相关性.