Central Research Institute of Natural Sciences, Magyar Tudósok körútja 2, 1117 Budapest, Hungary.
JenaBatteries GmbH, Otto-Schott-Straße 15, 07745 Jena, Germany.
Molecules. 2021 Feb 24;26(5):1203. doi: 10.3390/molecules26051203.
Flow batteries can play an important role as energy storage media in future electricity grids. Organic compounds, based on abundant elements, are appealing alternatives as redox couples for redox flow batteries. The straightforward scalability, the independence of material sources, and the potentially attractive price motivate researchers to investigate this technological area. Four different benzyl-morpholino hydroquinone derivatives were synthesized as potential redox active species. Compounds bearing central symmetry were shown to be about an order of magnitude less soluble in water than isomers without central symmetry. Counter ions also affected solubility. Perchlorate, chlorate, sulfate and phosphate anions were investigated as counter ions. The formations of different polymorphs was observed, showing that their solubility is not a function of their structure. The kinetics of the transformation can give misleading solubility values according to Ostwald's rule. The unpredictability of both the kinetics and the thermodynamics of the formation of polymorphs is a danger for new organic compounds designed for flow battery applications.
液流电池可以作为未来电网中的储能介质发挥重要作用。基于丰富元素的有机化合物作为氧化还原对，是氧化还原液流电池的一种有吸引力的替代品。其直接的可扩展性、材料来源的独立性以及潜在的有吸引力的价格促使研究人员研究这一技术领域。本文合成了四种不同的苄基吗啉对苯二酚衍生物作为潜在的氧化还原活性物质。结果表明，具有中心对称的化合物在水中的溶解度比没有中心对称的异构体低一个数量级。抗衡离子也会影响溶解度。本文研究了高氯酸盐、氯酸盐、硫酸盐和磷酸盐阴离子作为抗衡离子。观察到了不同多晶型物的形成，表明它们的溶解度不是其结构的函数。根据奥斯特瓦尔德规则，相转变的动力学会给出误导性的溶解度值。多晶型物形成的动力学和热力学的不可预测性，是为液流电池应用而设计的新有机化合物的一个危险。
