A Sustainable Recycling Route from Spent Sulfuric Acid Catalysts to Vanadium Pentoxide Precursor for the Production of Low‐Cost Na3V2(PO4)3@C Na‐Ion Batteries.

The extraction of vanadium from spent industrial catalysts is a widely practiced process globally due to the large quantities of material available with appreciable vanadium content. However, some of these spent catalysts are unresponsive to established extraction methods because they have different properties. Therefore, separate studies are necessary to deal with specific cases. This work demonstrates how the leaching step can limit the recovery of vanadium to the solution before the coprecipitation step. The NH4Cl‐H2SO4 synergetic system achieved a high vanadium leaching rate of up to 95 %, resulting in the preparation of high‐purity NH4VO3 with 75.45 % V2O5 content. This demonstrates the potential of the prepared V2O5 as a precursor for vanadium materials used in sodium‐ion batteries, allowing for the adjustment of the valence of vanadium. The Na3V2(PO4)3@C particles exhibit a discharge capacity of 110 mAh g−1 at a current density of 0.1 C and 90 mAh g−1 at 1 C. The synergistic leaching system provides a sustainable method for the recovery and reuse of vanadium from spent vanadium catalysts. This contributes to recycling efforts and the development of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]