Determination of the charge state of an all-vanadium redox flow battery by means of UV / Vis measurement

摘要

A method is described for determining the charge state of a vanadium redox flow cell in which the concentrations of V4 + and V5 + in the positive electrolyte are determined indirectly by mixing positive and negative electrolytes in certain proportions to increase the V5 + contained in the positive electrolyte to reduce. In this way, CT complexes of V4 + / V5 + are avoided whose concentration can not be determined directly due to the strong UV / Vis absorption. The method thus makes it possible to determine the concentrations of the negative and positive electrolytes via UV / Vis absorptions, which allows easy monitoring of the charge state of a vanadium redox flow battery. Also described is a method of operating a vanadium redox flow battery and devices suitable for implementing this method.