Boosting proton intercalation via sulfur anion doping in V2O3 cathode materials towards high capacity and rate performance of aqueous zinc ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) are a prospective solution for grid-scale energy storage. V₂O₃ has emerged as a promising cathode candidate with reversible two-electron redox capability for ZIBs. However, it still faces problems such as poor electronic conductivity and sluggish ion embedding kinetics. Herein, we report sulfur anion-doped V₂O₃ with tunneled structure based on a facile carbothermal reduction method, which can exhibit the significant impact of sulfur anion-doping on proton storage in vanadium-based cathode materials for high capacity and rate performance of ZIBs. The covalent bonds in S-V-O lead to accelerated charge transfer and elevated electronic conductivity. In-situ X-ray diffraction, synchrotron-based X-ray absorption spectroscopy combined with DFT calculations demonstrate that S doping effectively diminishes the adsorption and embedding energies of H⁺ in V₂O₃ and greatly boosts proton insertion kinetics. The co-intercalation of H⁺/Zn²⁺ helps compensate for the deficiency of Zn²⁺ insertion/extraction kinetics. Amorphous transition of crystalline V₂O₃ initiated from initial charging is conducive to mitigating stress and retaining stable cycling capacity. The typical sulfur-doped V₂O₃ achieves remarkable capacity (470.4 mAh·g⁻¹ at 0.5 A·g⁻¹), excellent rate capability (264.6 mAh·g⁻¹ at 10 A·g⁻¹) and stable long-term cyclability (231.2 mAh·g⁻¹ at 10 A·g⁻¹ after 2000 cycles). Furthermore, the corresponding pouch cells can deliver 26 mAh at 1 A·g⁻¹ after 250 cycles, holding great potential for practical applications.