Study of Transient Behavior of Vanadium Redox Flow Battery at Varying Flow Rates and States of Charge

The Vanadium Redox Flow Battery (VRB) is one promising candidate for grid type storage because of its long life time, modularity, active thermal management, and good cycle life. There are various parameters that affect the performance of VRB for example: temperature, flow rate, state of charge etc. Flow rate is an important parameter, since the electrolyte flow rate influences the reaction rate of the vanadium ions. It is also important because it has a substantial influence on the system efficiencies.

Ma et al. [1] investigated the effect of flow rate on the system capacity and the efficiency.  Fetlawai [2] investigated the effect of flow rate on the charge-discharge characteristics and on the gas evolution. It was established that flow rate is one of the important parameters which should be controlled to obtain high efficiency of VRB. The effect of the flow rate on the transient behavior of the battery has not got much attention which motivated this study.

We will present experimental results on the transient behavior of a VRB at various flow rates up to ca. 1 L/min. The battery was at 80% state of charge during experiment. It was observed that flow rate has a strong effect on the transient behavior of the battery (a typical examples is shown in Fig. 1). The load of the battery was varied in a regime typical for applications of VRBs. The results showed clear trends of the transient behaviour of the battery with changes of flow rate.  The implications of these findings for the development of control systems in grid energy storage system design with VRBs will be discussed.

[1] X. Ma, H. Zhang, C. Sun, Y. Zou, and T. Zhang, “An optimal strategy of electrolyte flow rate for vanadium redox flow battery,” J. Power Sources, vol. 203, pp. 153–158, Apr. 2012.

[2] H. A.-Z. A.-Y. Al-Fetlawi, “Modelling and simulation of all-vanadium redox flow batteries.” 14-Apr-2011.

[3]J. Chahwan, C. Abbey, and G. Joos, “VRB Modelling for the Study of Output Terminal Voltages, Internal Losses and Performance,” 2007 IEEE Canada Electr. Power Conf., pp. 387–392, Oct. 2007.