Numerical Analysis of Mass Transfer Mechanisms in Vanadium Redox Flow Batteries: Impact on Battery Performance

Abstract

Abstract Vanadium redox flow battery (VRFB) is considered a promising option for large-scale energy storage due to its safety, long lifespan, and environmental friendliness. However, mass transfer imbalances can negatively impact its performance. In this paper, a two-dimensional static isothermal model is established based on VRFB to simulate the distribution of ion concentration under different states of charge (SoC). Herein, the cell voltage at different SoC and the overvoltage at half-cell height are studied by changing the current density and electrolyte flow rate. Meanwhile, H+ flux at the half-height of the battery at various current densities is studied. The results show that with the increase of current density, the potential difference and the H+ flux between the positive and negative electrolytes increase, and the over-potential near the collector increases maximum. Moreover, optimizing electrolyte flow rate and current density is critical to reducing polarization effects and improving battery performance. This paper explores the effect of the mass transfer mechanism of vanadium redox flow battery on VRFB performance and provides a reference for the improvement of battery performance.