Communication—Observation of Arrhenius Behavior of Catholyte Stability in Vanadium Flow Batteries

Abstract

The stability of typical vanadium flowbattery (VFB) catholytes with respect to precipitation of V2O5 was investigated at temperatures in the range 30–60◦C. In all cases a precipitate formed after an induction time, which decreased with increasing temperature and concentration of VV and increased with concentration of sulfate. Arrhenius-type plots are shown for two typical solutions. These have excellent linearity and have similar slopes which yield an apparent activation energy of 1.79 eV (172 kJ mol−1). The variation of induction time with temperature for various concentrations of VV was simulated, and stability diagrams for additive-free VFB catholytes were generated.