Inhibition of vanadium cathode dissolution in zinc-ion batteries via niobium pillaring

Abstract

Vanadium (V)-based oxides are considered promising cathodes for aqueous zinc-ion batteries (AZIBs) due to their multiple oxidation states and diverse crystal structures. However, their sluggish kinetics and severe V-dissolution result in rapid capacity fading and an unsatisfactory cycle life. Herein, a niobium (Nb) pillaring coupling with polyethylene glycol (PEG) assistance strategy has been proposed for the first time, which overcomes the limitation of separation inability of Nb-doped V oxides. The doped Nb acted as a structural pillar contributes to good structural stability, and the PEG-assitance Nb-doped V₃O₇·H₂O (PNVO) featured abundant oxygen vacancy and enhanced kinetics, leading to good rate performance. This approach results in high reversible capacities of 403 mAh g⁻¹ and 244 mAh g⁻¹ at 1 A g⁻¹ and 10 A g⁻¹, respectively, and remarkable cyclability with 68% capacity retention after 3000 cycles at 5 A g⁻¹. The quantitative comparison of V-dissolution suggests that PNVO-2 exhibits a low dissolution rate of 8.93%, while that for PVO and VO is 11.25% and 16.07%, respectively. These findings not only confirm the positive effect of Nb-pillaring on the inhibition of V-dissolution but also highlight the promising practical application of V-based cathodes for AZIBs.