THE CONCENTRATED V(IV)/V(V) ELECTROLYTE OPTIMIZATION AND ELECTRODE PROCESS INVESTIGATION IN A VANADIUM REDOX BATTERY

摘要

The higher vanadium concentrations are required to reduce the size and weight of the battery. The main limitation for the vanadium electrolyte concentration is the precipitation of V (IV) ion. In this paper, the electrode process of concentrated V (IV) species was studied at a Pt electrode with cyclic voltammetry, linear polarization and impedance techniques. The results revealed that the solubility of VOSO4 decreases continuously with increasing H_2SO_4 concentration. In 2mol/L VOSO_4 solution containing 3mol/L H_2SO_4, the V (IV) electrolyte has the highest peak current and the best reversibility. Adding alkali metal sulfate and organics in above-mentioned electrolyte respectively, the effect of the additives on the electrolyte properties was discussed and the electrode process was investigated. The results indicate that the hydrophilic organism improves the stability of V (IV)/V (V) species, the alkali metal sulfate elevates the peak current slightly, and there is no adverse effect of the additives on the redox reaction in vanadium sulfate solution.