High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

Abstract

Although Vanadium Redox Flow Batteries (VRFB) are suitable for grid-scale applications, their power-related cost must be reduced in order to boost the use of this technology in the market, allowing their widespread commercialization. One effective way to make the VRFB a competitive and viable solution could be through new strategies for improving the electrocatalytic activity of the electrodes with enhanced electrolyte/electrode interface characteristics. Herein, we report the synergistic effect demonstrated by N- and WO3- decorated carbon-based positive electrode, named HTNW electrode, which demonstrates the feasibility of achieving: i) enhanced electrocatalytic activity, achieving large current density and high reversibility towards VO2+/VO2+ couple (promotion of oxygen and electron transfer processes), ii) decrement of the electron-transfer resistance from 76.18¿O to 13.00¿O for the pristine electrode and HTNW electrodes, respectively; iii) 51% of the electrolyte utilization ratio at high rates (i.e. 200¿mA¿cm-2) with 70% of energy efficiency; iv) increment of more than 50% of the power–peak in comparison with pristine electrode.