Electrical performance analysis of an innovative Vanadium redox flow battery stack for enhanced power density applications

Electrochemical energy storage is extensively investigated lately for numerous stationary and transportation applications, being efficient and highly customizable. Vanadium redox flow batteries (VRFB) in particular are feasible in a wide power to capacity ratio, making them suitable for both high power and high capacity requirements in modern energy systems. However, their performances are strongly dependent on the geometry of the stack, shunt current phenomenon development affecting the electrical behavior. This paper addresses the detailed electrical modeling of a VRFB stack aiming to assess the shunt current distribution, discussing the global performances for different configurations, varying series cells and stack grouping at parity of cells (specifically, single stacks of 5, 10, 20 a 40 series cells and two additional configurations 4 x 10 cells and 2 x 20 cells). The research outcomes provide useful insights regarding their electrical behavior in several operating conditions, showing that the shunt current can reach 20% of the nominal current in a 40 cells stack. Moreover, a reduction of 34% in the global shunt current can be achieved by coupling the 40 cells in 4 x 10 groups.