Theoretical and technological aspects of flow batteries:Shunt current formation and control

All-vanadium redox flow batteries(VFBs) are made of a series of single cells connected in parallel and packaged into a stack. A common channel connects single cells and distributes positive or negative electrolyte into each cell. Due to the electric potential in the stack, vanadium ions migrate along a specific direction in the positive or negative electrolyte that flows through the common channel,leading to the formation of shunt current and hence energy loss. This paper analyses the causes of shunt current formation, develops a mathematical model based on the analyses, and provides strategies to constrain the formation of shunt current. It is found that the formation of shunt current and hence the associated energy loss can be effectively reduced through a proper design of the flow channels.