High efficiency and short-process for preparing high-purity VOSO4 electrolyte

Abstract

In response to the global explosive growth demand for all-vanadium redox flow batteries in the field of energy storage, the development of efficient, low-cost, and short processes for VOSO₄ electrolyte production is a critical challenge. Here, we present a novel process for the preparation of high-purity VOSO₄ electrolyte, utilizing calcified vanadium slag as the raw material, with H₂SO₄-C₆H₈O₆ synergistic reduction leaching combined with solvent extraction. The synergistic leaching system simultaneously achieves efficient vanadium extraction and the reduction of VO₂⁺ to VO²⁺. This effectively mitigates the long-standing hydrolysis challenge in the vanadium recovery process from vanadium slag via the calcification method. Under the conditions of leaching at pH 1.6, with a C₆H8O₆ dosage of 10 g/L, a leaching time of 30 min, and a leaching temperature of 60 °C, the vanadium leaching efficiency is 98.15 %. The leachate undergoes direct three-stage counter current extraction, where impurities are selectively separated from VO²⁺. Subsequently, more than 99.31 % of vanadium is recovered as high-purity VOSO₄ electrolyte through stripping, the quality of VOSO₄ far exceeds the Grade I standard specified in China. The total recovery efficiency of vanadium has reached 97.47 %, an increase of 7 to 10 percentage points compared to the existing VOSO₄ preparation process. This new process is poised to revolutionize the traditional preparation pathway of VOSO₄ by significantly increases resource utilization, simplifies processes, reduces costs, and mitigates potential environmental hazards.