The speciation of vanadium in the electrolyte of vanadium redox flow batteries (VRFBs) is important to determine the state of charge of the battery. To obtain a better understanding of the transport of the different vanadium species through the separator polymer electrolyte membranes, it is necessary to be able to determine concentration and species of the vanadium ions inside the nanoscopic water body of the membranes. The speciation of V in the electrolyte of VRFBs has been performed by others at the synchrotron by X-ray absorption near-edge structure analysis (XANES). However, the concentrations are quite high and not necessarily justify the use of a large-scale facility. Here, we show that vanadium species in the electrolyte and inside the ionomeric membranes can be determined by laboratory XANES. We were able to determine V species in the 1.6 M electrolyte with a measurement time of 2.3 h and V species having a concentration of 9.8 g kg−1 inside the membranes (178 µm thick) with a measurement time of 5 h. Our results show that laboratory XANES is an appropriate tool to study these kind of samples.

中文翻译：

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XANES 实验室研究钒氧化还原液流电池中的钒种类

钒氧化还原液流电池 (VRFB) 电解液中钒的形态对于确定电池的充电状态非常重要。为了更好地了解不同钒物质通过隔膜聚合物电解质膜的传输，有必要能够确定膜的纳米级水体中钒离子的浓度和种类。其他人在同步加速器上通过 X 射线吸收近边结构分析 (XANES) 对 VRFB 电解质中的 V 进行了形态分析。然而，浓度相当高，不一定证明使用大型设施是合理的。在这里，我们展示了电解质和离聚物膜内部的钒种类可以通过实验室 XANES 确定。我们能够确定 1 中的 V 物种。-1在膜内（178 µm 厚），测量时间为 5 小时。我们的结果表明，实验室 XANES 是研究这类样品的合适工具。