A Reversible Anodizing Strategy in a Hybrid Electrolyte Zn-Ion Battery through Structural Modification of a Vanadium Sulfide Cathode

Rechargeable aqueous Zn-ion batteries (ZiBs) have received significant attention owing to their low cost and environmental friendliness. The charge storage mechanism of ZiBs generally depends on the cationic redox conversion. The anodic redox conversion is still rare due to the lack of suitable cathode materials and electrolytes, which may impede the ZiB performance. The present investigation focuses on enhancing the ZiB performance through in situ involvement of disulfide redox chemistry from a patronite Mn-doped VS4 crystal in a 1 M Zn(OTf)2 water/acetonitrile (ACN) hybrid electrolyte. Simultaneous involvement of cationic and anionic redox conversion during the charging/discharging process enhances the specific capacity as high as ∼547 mA h g–1 at 0.2 A g–1 current density. The water/ACN hybrid solvent effectively improves the working voltage and suppresses Zn dendrite formation, resulting in superior cycling performance. The conversion of the VS4 crystal phase and intercalation of H+/Zn2+ in the cathode have been investigated through ex situ X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman studies.