Effect of exerted magnetic field on the performance of non-aqueous iron-vanadium redox flow battery with deep eutectic solvent (DES) electrolyte

In this work, a kind of ethylene glycol-based deep eutectic solvent (DES) is explored as electrolyte of an iron-vanadium redox flow battery and the effect of the applied magnetic field is studied, including the physical and electrochemical characteristics of positive and negative DES electrolytes, as well as the performance of DES redox flow battery with/without magnetic field. The experimental results show that after adding a magnetic field, the viscosity of the DES electrolytes decreases, while the conductivity increases. As the intensity of the added magnetic field becomes larger, both the oxidation and the reduction peak current densities of the positive and negative DES electrolytes increase. With a magnetic field of 605 mT, the oxidation peak current density increment is up to 41.56%, and the reduction peak increases up to 30.74%. The exertion of magnetic field also leads to increased limiting current and power density, improved energy efficiency, and extended battery operating time of the iron-vanadium DES-electrolyte redox flow battery. This work exhibits a promising prospect for the application of an external magnetic field to non-aqueous redox flow batteries.