A comprehensive modelling study of all vanadium redox flow battery : revealing the combined effects of electrode structure and surface property

Abstract

To investigate the combined effects of electrode structural parameters and surface properties on the vanadium redox flow battery (VRFB) performance, a comprehensive model of VRFB is developed in this study. One feature of this study is that a practical range of working temperature is fully considered in the numerical simulations. Excellent VRFB performance was achieved by modified fibrous electrodes with 0.5 mm thickness and 0.9 porosity. The electrode with modified fibre of large diameter 20 μm shows improved battery performance with a low pressure drop. Without fibre modification, although VRFB with θ = 7° aligned fibre electrode reaches the highest limiting current density, it has an evidently high pressure drop. At 323.15 K, the VRFB with θ = 45° aligned fibre electrode showed 21 % higher limiting current density and 36 % lower pressure drop than VRFB with xy-plane isotropic electrode. Noteworthy, after the fibre surface modification, the sufficient specific surface area can be ensured, which leads to the insignificant effects of aligned electrode design. This model provides an insightful understanding of combined effects of electrode structure and surface property on the VRFBs performance at various temperatures.