A parametric analysis of the output voltage of all-vanadium redox-flow battery system

Vanadium redox flow battery (VRFB) becomes a global technology used in stationary applications like grid storage. The characteristics of output voltage during the charge-discharge cycles and the resulted power of VRFB are strongly based on solving a multidisciplinary problem. In this paper, a 2 D steady state numerical model for the operation of a single VRFB has been formulated, validated with good agreement, and tested. The output voltage response of VRFB at different state of charges (SOCs) has been investigated under range of volumetric flow rates and current densities. Next, a comprehensive parametric analysis, sensitivity study, for the major electrode and electrolyte material properties is conducted which can improve confidence in model predictions. The results showed that increasing flow rate can help to minimize concentration polarization, however, pumping power would be dominated. A low flow rate can cause some poor covered regions, but would reduce pumping power. Based on the sensitivity results, only cathode reaction rate, specific surface area, conductivity of porous electrode and electrolyte, and carbon felt porosity are input parameters that dominate the simulation results. It is expected that this proposed model would be applicable to most flow batteries architectures and can be extended to stack flow batteries.