Vanadium is a valuable and rare resource widely used in chemical manufacturing, military affairs, aerospace, metallurgical industry and other fields [1], and China is rich in vanadium resources, accounting for 34% of the world's total, ranking first in the world. Vanadium mainly in the form of vanadium-titanium magnetite and vanadium-bearing coal [2]. As a new type of energy storage technology, vanadium redox flow battery has been widely studied due to its advantages of environmental protection, long-life, safety and flexible power design [3]. Vanadium electrolyte is an important component of vanadium batteries, and it is directly related to the performance and cycle life of vanadium batteries [4]. Solvent extraction is widely used for the extraction of vanadium. It can prepare electrolyte from vanadium-containing solution, eliminating the steps of vanadium precipitation, impurity removal and dissolution, which meets the requirements of energy saving and environmental protection. Based on the above, we propose a clean and short process for the preparation of vanadium electrolyte from vanadium shale leaching solution by solvent extraction.

An oxidative stripping system, with the low concentrations of hydrogen peroxide and sodium hypochlorite was introduced to facilitate vanadium recovery and further separation of impurities from the leach solution. In order to investigate the mechanism, FTIR and Raman spectroscopy were used to investigate the changes in valence bonding before and after extraction and stripping. The concentration of vanadium and other impurities in the vanadium-rich liquid was investigated by ICP to determine whether it complied with national standards（GB/T 37204-2018）.

After reduction and enrichment, a high purity vanadium electrolyte with low concentration of impurities was prepared. The prepared electrolyte exhibits acceptable electrochemical and charge/discharge properties. The method saves a large amount of preparation cost than the traditional method and does not produce ammonia, nitrogen or harmful gases. The technology is economically reasonable and eco-friendly, and is expected to be applied to large-scale production and promote the development of vanadium redox flow battery and new energy.