Organic Molecule Intercalation into a Vanadate Cathode for Enhanced Electrochemical Stability in Aqueous Zinc-Ion Batteries

Vanadium oxides, especially hydrated forms such as V2O5·nH2O (HVO), present promising cathode candidates for aqueous zinc-ion batteries (AZIBs) because of their multivalent redox states and structural polymorphism and the earth-abundant nature of the vanadium source. Nevertheless, the existing cathode materials are plagued by slow Zn2+ diffusion kinetics, which severely compromise their rate performances and long-term cyclability. In this work, we present a unique cathode material for AZIBs, saccharin-intercalated vanadium oxide hydrate (Sac-V2O5, SVO). An unanticipated contraction of vanadium oxide in interlayer spacing is found after the Sac-intercalation. The preinserted saccharin molecules not only extrude the weakly bonded water between the V–O layers but also weaken the electrostatic interactions between Zn2+ and the V–O lattice. The combined effect of these modifications results in a superior cycling stability and enhanced reaction kinetics. Consequently, the modified cathode achieves an outstanding specific capacity of 357 mAh g–1 at 0.5 A g–1 and maintains 98.5% capacity after 3000 cycles at 10.0 A g–1. Remarkably, the cathode maintains superior rate performances even under a low operating temperature (−20 °C) and exhibits excellent capacity retention (98.7%) over 1000 cycles at 2 A g–1. This research promises to enhance the viability of vanadium-based cathodes via organic ion preintercalation for AZIBs.