The Mechanism and Modelling of Shunt Current in the Vanadium Redox Flow Battery

Abstract

To date, no physical model has been proposed to describe the mechanism of shunt currents in bipolar electrochemical reactors with a common electrolyte manifold. In this paper, we show that under the influence of the cell voltage driving force, the bipolar electrode provides an internal electrical pathway that allows electrons to flow from the negative half-cell of one cell, to the positive half-cell of the adjacent cell, leading to self-discharge reactions that can occur even when the stack is at open-circuit. This is made possible, by the presence of the interconnecting channels and common electrolyte manifolds that enable the flow of hydrogen or other charge carrying ions to complete the circuit. The larger the number of cells in the cell stack, the larger the number of internal pathways for electrons and protons to flow, so the greater the shunt current losses.[a] Prof.

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“…The existence of shunt currents decreases the system's capacity and energy efficiency. 6 Xiong et al 7 developed a hydraulic model to estimate the pump power consumption for optimal battery efficiency. They found that the design of the distribution channels and the manifold is a trade-off between shunt current losses and pump power losses due to hydraulic resistance.…”