Development of economical and highly efficient electrolyte using vanadium pentoxide for vanadium redox flow battery

Vanadium pentoxide can be an inexpensive replacement to vanadium sulfate in synthesizing vanadium redox flow battery (VRFB) electrolytes. In this study, VRFB electrolyte is synthesized from vanadium pentoxide using an indigenously developed process and setup. In order to have the same performance as that of vanadium sulfate, the supporting electrolyte environment constituted by H+ and sulfate ion is replicated based on the calculations from standard synthesis mechanisms. The calculations reveal that 4 M H2SO4 is required while preparing 1.5 M Vn+ electrolyte from V2O5 to replicate 1.5 M Vn+ in 2.5 M H2SO4 from VOSO4. The effect of variation of sulfuric acid concentration is explored using thermal stability testing, which shows stable V(V) electrolytes for more than 30 days for 4 M H2SO4 concentration. Furthermore, the electrochemical performance of developed electrolyte from vanadium pentoxide shows similar charge–discharge profile, yet 1/5 the cost as compared to vanadium sulfate.