Graphite felt electrode modified by square wave potential pulse for vanadium redox flow battery

In this paper, graphite felts treated by square wave potential pulse were modified as electrode for vanadium redox flow battery (VRFB). X-ray photoelectron spectroscopy measurements indicated that the treatment for graphite felt can introduce oxygen-containing groups on the surface. Moreover, graphite felt can also be etched to form nano-scale pores, without damage of mechanical property by treatment. The formed nano-scale pores and introduced oxygen-containing groups can enhance the wettability of electrolyte on graphite felt and electrochemical kinetics of V(II)/V(III) and V(IV)/V(V) redox reactions. The treated graphite felt was employed as electrode to assemble the static cell, and its electrochemical performance was evaluated. The cell using modified graphite felt exhibits larger discharge capacity and energy efficiency compared with the pristine graphite felt. The average energy efficiency for graphite felt treated for 1600s can reach 87.0% at 30mAcm(-2), 4.2% larger than that for the pristine graphite felt. This study demonstrates that the square wave potential pulse treatment is an efficient way to enhance the electrochemical properties of graphite felt for VRFB system. Copyright (C) 2016 John Wiley & Sons, Ltd.