An additive-free approach for restoring the performance of vanadium redox flow batteries affected by V2O5 precipitation

Vanadium redox flow batteries (VRFBs) face a significant challenge during high-temperature operation, as the precipitation of V 2 O 5 on the positive side obstructs electrolyte flow, drastically diminishes battery capacity, and eventually leads to battery failure. While various additives have been explored to mitigate V 2 O 5 precipitation, it continues to occur at temperatures exceeding 40 ℃. Unfortunately, there is a lack of research focused on effective methods for removing V 2 O 5 from the battery system. The conventional approach requires disassembling the battery stacks to eliminate V 2 O 5 , a process that is not only labor-intensive and costly but also risks damaging the performance and components of the battery. In this study, we introduce an additive free strategy that enables the removal of V 2 O 5 from the battery without the need for disassembly, thereby fully restoring battery capacity. This method is both efficient and simple, offering a cost-effective solution for V₂O₅ dissolution while potentially simplifying VRFB electrolyte manufacturing. The formation of V 2 O 5 at high temperature during cycling and the insolubility of V 2 O 5 under room temperature during electrolytes manufacturing process are the two critical issues in VRFBs, which can lead to shutdown battery and increase capital costs, respectively. Here, we propose a reductive solvent strategy and effectively address these difficulties. • Presenting a reductive solvent approach for restoring VRFB performance. • Eliminating V 2 O 5 from the VRFB system without disassembling the battery. • Restoring the performance of VRFB after the V 2 O 5 precipitation occurs. • Streamlining the electrolyte manufacturing process for VRFBs.