Factor analysis of the uniformity of the transfer current density in vanadium flow battery by an improved three-dimensional transient model

Abstract

Vanadium flow battery has been regarded as one of the most promising candidates for large-scale energy storage, due to its attractive features of high safety, high performance-price ratio and environmental friendliness. The uniformity of transfer current density is one of the crucial factors affecting the performance of a vanadium flow battery. More uniform distribution of transfer current density will reduce the polarization and improve the battery reliability. In this work, a three-dimensional transient model in combination of the vanadium ions crossover through the separator has been developed. Based on the model, the effect of the applied current density, electrode porosity and electrolyte flow rate on the uniformity of transfer current density has been investigated. The result indicates that a lower applied current density, higher electrode porosity or higher electrolyte flow rate is beneficial to obtain a more uniform transfer current density and a reduced battery polarization. By comparison, the electrode porosity shows the most prominent effect on the uniformity of transfer current density, and a higher porosity is verified to be able to attain a better stability in several charge-discharge cycles. Finally, a preliminary study for an industrial scale battery designs has been performed based on an amplifying model.