Carbon nanowalls thin films as nanostructured electrode materials in vanadium redox flow batteries

► Carbon nanowalls thin films as positive electrodes in vanadium redox flow batteries. ► Interconnected networks of 2D-graphene nanostructures perpendicular to the substrate. ► Large amount of exposed graphitic edge planes with oxygenated functional groups. ► Long-term stability of the nanostructured electrodes. ► Low overpotential, high peak current densities, fast e− transfer kinetics for V4+/5+.