The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery
The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery
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DOI：
10.1016/j.jpowsour.2016.10.017
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发表时间：
2016-12
影响因子：
9.2
通讯作者：
T. D. Nguyen;A. Whitehead;G. Scherer;N. Wai;M. O. Oo;A. Bhattarai;G. C. Chandra;Zhichuan J. Xu-
中科院分区：
文献类型：
--
作者：
T. D. Nguyen;A. Whitehead;G. Scherer;N. Wai;M. O. Oo;A. Bhattarai;G. C. Chandra;Zhichuan J. Xu-
尽管有许多期望的性质，但钒氧化还原液流电池在正极电解质中开始沉淀之前在可持续承受的最大操作温度下受到限制。已经提出了许多添加剂来改善带电正电解质的热稳定性。然而，我们已经发现，在实验室测试中显示的表观稳定性通常只是测试方法的人为因素，并且是由添加剂的氧化引起的，V（V）相应地部分还原为V（IV）。这不会改善电解质在操作系统中的稳定性。在这里，我们研究了一些典型的有机添加剂的氧化与羧基，醇，和多官能团，在硫酸溶液中含有V（V）。紫外-可见光谱和滴定结果表明，许多化合物降低了钒电解液的荷电状态（SOC），例如，添加1%wt的EDTA二钠盐，连苯三酚和抗坏血酸，分别降低了27.8%，88.5%和81.9%。电池循环也表明了有机添加剂对电池性能的影响，有效充电容量显著降低。此外，还介绍了一种标准的热稳定添加剂筛选方法，以快速筛选出适合钒正极电解液的添加剂。
Despite many desirable properties, the vanadium redox flow battery is limited, in the maximum operation temperature that can be continuously endured, before precipitation begins in the positive electrolyte. Many additives have been proposed to improve the thermal stability of the charged positive electrolyte. However, we have found that the apparent stability, revealed in laboratory testing, is often simply an artifact of the test method and arises from the oxidation of the additive, with corresponding partial reduction of V(V) to V(IV). This does not improve the stability of the electrolyte in an operating system. Here, we examined the oxidation of some typical organic additives with carboxyl, alcohol, and multi-functional groups, in sulfuric acid solutions containing V(V). The UV–vis measurements and titration results showed that many compounds reduced the state-of-charge (SOC) of vanadium electrolyte, for example, by 27.8, 88.5, and 81.9% with the addition of 1%wt of EDTA disodium salt, pyrogallol, and ascorbic acid, respectively. The cell cycling also indicated the effect of organic additives on the cell performance, with significant reduction in the usable charge capacity. In addition, a standard screening method for thermally stable additives was introduced, to quickly screen suitable additives for the positive vanadium electrolyte.