Eco-friendly synthesis of VO(2) with stripped pentavalent vanadium solution extracted from vanadium-bearing shale by hydrothermal process in high conversion rate

VO(2)(B) has shown excellent cathode performance in lithium batteries and become a hot research topic in recent years. A stripped vanadium solution extracted from vanadium-bearing shale containing a high concentration of vanadium and certain amounts of impurities was used as a vanadium source to synthesize VO(2)(B) by hydrothermal process. The VO(2) conversion rate can reach as high as 99.47% in a reaction time of 8 h, and this is the highest result reported. The crystalline structure and morphology of the synthesized products were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). Furthermore, the electrochemical properties of VO(2)(B) in lithium-ion batteries were investigated. The results indicated that the VO(2)(B) has the initial specific discharge capacity of 192.0 mAh g(−1). Stripped vanadium solution is a raw material for producing V(2)O(5) and NH(4)VO(3), which are indispensable vanadium sources in VO(2) synthesis. Therefore, synthesis of VO(2) via hydrothermal reduction by oxalic acid using stripped vanadium solution extracted from vanadium-bearing shale as a direct vanadium source is an eco-friendly, innovative and efficient method, and will have a great impact on VO(2) synthesis.