High efficiency of CO2-activated graphite felt as electrode for vanadium redox flow battery application

Abstract A simple method for preparing CO 2 -activated graphite felt as an electrode in a vanadium redox flow battery (VRFB) was employed by the direct treatment in a CO 2 atmosphere at a high temperature for a short period. The CO 2 -activated graphite felt demonstrates excellent electrochemical activity and reversibility. The VRFB using the CO 2 -activated graphite felts in the electrodes has coulombic, voltage, and energy efficiencies of 94.52%, 88.97%, and 84.15%, respectively, which is much higher than VRFBs using the electrodes of untreated graphite felt and N 2 -activated graphite felt. The efficiency enhancement was attributed to the higher number of oxygen-containing functional groups on the graphite felt that are formed during the CO 2 -activation, leading to improving the electrochemical behaviour of the resultant VRFB.