A green and cost-effective approach for high-purity VOCl3 preparation and its application in high-performance vanadium redox flow batteries

In the context of the global energy transition, the intermittency and instability of renewable energy have become major bottlenecks limiting its large-scale application. Vanadium redox flow batteries (VRFBs), recognized for their long cycle life, high safety, and environmental benefits, are ideal solutions for large-scale energy storage. The cost and performance of the electrolyte are critical factors determining the efficiency and economic viability of the battery. However, the preparation of vanadium electrolytes faces challenges, including complex production processes and high costs. Thus, developing high-concentration, high-performance, and low-cost vanadium electrolytes while ensuring green production of raw materials is an urgent technical challenge. This study presents a short-process clean method for the production of high-purity VOCl 3 from NaVO 3 extracted from vanadium slag, which is applied to the sulfate-chloride electrolyte system of VRFBs. In this system, VOCl 3 serves as the Cl − source, significantly reducing production costs by eliminating the need for additional HCl. Compared to traditional vanadium raw materials (e.g., V 2 O 5 and VOSO 4 ), the energy efficiency (EE) of the electrolyte is improved by 13.6 %. This research presents an efficient and cost-effective approach for the sustainable production of vanadium electrolytes, providing significant support for the advancement of high-performance and economically viable VRFB technology.