Stability of highly supersaturated vanadium electrolyte solution and characterization of precipitated phases for vanadium redox flow battery

The vanadium redox flow battery (VRFB) has been receiving great attention in recent years as one of the most viable energy storage technologies for large-scale applications. However, higher concentrations species are required H2O-H2SO4 electrolyte order to improve VRFB density. This might lead unwanted precipitation compounds, whose nature not accurately characterized yet. For this purpose, study reports preparation V(II), V(III), V(IV) and V(V) supersaturated solutions a 5 M H2SO4-H2O by an electrolytic method, from only sulfate compound commercially available (VOSO4). precipitates obtained ageing stirred representative solids that may form operated with such solutions. solid phases identified using thermogravimetric analysis, X-ray diffraction SEM. We report dissolved V(III) precipitate crystals VSO4, V2(SO4)3 VOSO4 hydrates their anhydrous form; conversely amorphous V2O5 oxide partially hydrated. measured hydration degrees (respectively 1.5, 9, 3 0.26 mol H2O per compound) significantly affect overall engineering operating high concentrations.