PbO2-modified graphite felt as the positive electrode for an all-vanadium redox flow battery

Abstract A novel approach for enhancing the electrochemical performance of graphite felt electrodes by employing non-precious metal oxides is designed for an all-vanadium redox flow battery (VRFB). Lead dioxide (PbO 2 ) is prepared through pulse electrodeposition method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance of the prepared electrode is evaluated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Results show that PbO 2 exhibits excellent electro-catalytic activity and reactive velocity to vanadium redox couples. The coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of the vanadium redox flow battery with as-prepared electrodes at 70 mA cm −2 are 99.5%, 82.4%, and 82.0%, respectively; these values are much higher than those of a cell assembled with bare graphite felt electrodes. The outstanding electro-catalytic activity and mechanical stability of PbO 2 are advantageous in facilitating the redox reaction of vanadium ions, leading to the efficient operation of a vanadium redox flow battery.