Industrial waste-derived vanadium recovery for high-performance Na3V2(PO4)2F3@C sodium-ion battery application

Abstract

Conversion of hazardous vanadium spent catalysts (VSCs) to high added value vanadium-based materials is an effective solution for environmental remediation as well as cost-effective energy storage applications. In the present work, we introduce a new green hydrometallurgical process based on a novel synergistic sulfuric acid–hydrazine monohydrate (H₂SO₄–N₂H₄·H₂O) leaching system, achieving a high vanadium extraction of 97.8%. The purified vanadyl sulfate solution (99.96%) of the subsequent solvent extraction was converted into V₂O₅ and utilized for the production of Na₃V₂(PO₄)₂F₃@C (NVPF@C) cathode material via a solid-state approach for SIB application. The NVPF@C electrodes exhibited an interesting electrochemical performance, delivering 115 mAh g⁻¹ at 0.2C and retaining 89% capacity after 100 cycles at 1C, with remarkable rate capability. Economic and environmental assessment indicated savings of 72.9% in vanadium pentoxide cost as well as a range of 68.6–96.7% in greenhouse gas emission reduction compared with conventional leaching systems. This study highlights the feasibility of closing the loop for vanadium resources, offering a scalable and environmentally friendly route to battery-grade precursors. The approach not only validates the use of recycled vanadium in high-performance sodium-ion batteries but also emphasizes the integration of circular economy principles and sustainable practices in next-generation energy storage technologies.