The recent rapid growth of renewable energy technologies creates the necessity for innovation in energy storage. Unlike other battery system, vanadium flow batteries (VFBs) can be charged and discharged without degradation making them highly suited for electricity grid energy storage.
In a VFB the electroactive species are dissolved in the electrolytes. The redox couples in the negative and positive half-cells are VII/VIII and VIV/VV, respectively. The energy efficiency and maximum power of these batteries depend on the kinetics reactions at the electrode. Poor kinetics results in the requirement of large electrode overpotential resulting in significant voltage inefficiency.
The kinetic of such redox systems varies greatly depending on the electrode state. In the case of the VIV/VV redox couple, the rate constants at carbon electrodes have been reported both to decrease and increase after anodic treatment. We reported for a range of carbon materials that the electrode kinetics of VIV/VV activated after cathodic treatment and deactivate after anodic treatment. In this presentation we further investigate the effect of the electrochemical treatment on the electrode kinetics by controlling the upper and lower treatment potentials experienced by the electrode. We will present the resulting dependency of electrode kinetics on the range of the electrochemical treatment window experienced by the electrode
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