Preparation of V4+electrolyte by nanofluid-based electrocatalytic reduction of V2O5 for vanadium redox flow batteries

Abstract

The electrolyte employed in the vanadium redox flow battery (VRFB) is typically produced on an industrial scale through a secure and contaminant-free electrolysis process. However, the electrolysis rate is relatively sluggish, leading to elevated energy consumption. Herein, we propose a cost-effective method for electrolytic production of V(IV) electrolytes with carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) as the electrocatalyst and explore their effects on the electrolysis process. The results indicate that adding MWCNTs-COOH nanoparticles enhances the reactive sites of the electrode, thus improving the electrochemical activity of the electrolyte. The 0.1 wt% nanoparticle demonstrates the optimal catalytic performance for reducing V(V) to V(IV). Compared to the traditional electrolysis method, the proposed approach exhibits a 6.67% increase in electrolysis rate, a 15.57% reduction in energy consumption, and a notable relief in electrode corrosion. Furthermore, cyclic charge/discharge experiments illustrate that the prepared nanofluidic electrolyte exhibits superior performance in terms of voltage efficiency, Coulombic efficiency, energy efficiency, and discharge capacity retention. This invention offers a novel concept for vanadium electrolyte preparation, which reduces energy consumption and cost and improves the system's energy efficiency, showing great promise for practical VRFB applications.