Locating Shunt Currents in a Multistack System of All-Vanadium Redox Flow Batteries

Abstract

An all-vanadium redox flow battery (VRFB) system, with multiple stacks, is typically used for large-scale electrical energy storage applications. In a VRFB system, pumps deliver positive and negative electrolytes, through a piping system, to each stack. Because the electrolytes are electrically conductive, shunt currents can occur within a multicell stack and within the piping system, connecting the stacks due to the voltage differences between cells and between stacks. Shunt currents cause energy loss and are affected by the number of cells in a single stack, the number of stacks, and the piping system dimensions. In this study, we develop a mathematical model, based on Kirchhoff's law, to locate shunt currents in a multistack system. Using this model, we estimate the charge efficiency with various numbers of stacks. The results show that the shunt currents in the central stacks are larger than the currents in other stacks. In addition, the piping system dominates the distribution of the electrolytes, and the shunt currents gradually shift from inside the stack to the piping system.

Promising Material Based on Paraffin‐Impregnated Graphite Foil with Increased Electrochemical Stability for Bipolar Plates of Vanadium Redox Flow Battery

“…Electrolytes are distributed between each half‐cell of MEA by means of electrolyte supply channels and circulation pumps. Since electrolytes are ionic conductors, shunt currents can be obtained in the manifolds, distribution channels, and pipings [32,33] . Shunt currents not only reduce a battery's capacity and efficiency but can also damage cells components‐ BP, electrodes, and current collectors.…”

“…Since electrolytes are ionic conductors, shunt currents can be obtained in the manifolds, distribution channels, and pipings. [32,33] Shunt currents not only reduce a battery's capacity and efficiency but can also damage cells components-BP, electrodes, and current collectors. The value of shunt current of common battery stacks can be estimated as one to ten mA cm À 2 .…”

A Review on Vanadium Redox Flow Battery Storage Systems for Large-Scale Power Systems Application

“…It is worth noting that the pressure loss is directly proportional to the channel's length [197]. Strategies to reduce the shunt current losses include decreasing the electrolyte's conductivity, reworking the geometry of the flow channel and cell manifold, optimizing the piping system, and optimal stack design [194], [198].…”

Comprehensive Analysis of Critical Issues in All-Vanadium Redox Flow Battery

“…The stack layout causes transmission delay and concentration polarization. The optimal acquisition of EE and system efficiency (SE) and high costs constrain battery applications. , The above problems will seriously restrict the development of VRFBs. Another thing to be stressed is that there are also engineering problems with VRFBs that can affect battery core performance, such as electrochemical degradation of components, electrolyte leakage, and mechanical failure of critical components .…”

“…Xu and Zhao 119 summarizes the latest RFB research progress and introduces the future and potential of the modeling method such as the porous medium model, the lattice Boltzmann method, and the stack-level network model. Chou et al 50 discuss that VRFB modeling is of great significance to the improvement of the battery. The modeling method is roughly divided into three categories: macro method, micro method, and molecular/atomic method.…”