Dual-vapour-thermal engineering evoking bound water pathways of vanadium oxide for high-rate and durable zinc-ion storage

Abstract

Vanadium oxides have attracted extensive attention as promising cathode materials for aqueous zinc-ion batteries (AZIBs) owing to their variable valences and laminar structures. However, the strong interaction between divalent Zn2+ and the [VOn] host lattice limits its application. In this study, a facile dual-vapour-thermal engineering strategy was proposed for the first time to reconstruct V2O5 as an advanced cathode for AZIBs. Synchrotron radiation X-ray adsorption and photoelectron spectroscopies revealed that the high pressure and thermal environments of the ethanol/water dual-vapour phase trigger the fast formation of oxygen-deficient vanadium oxide hydrates (VPH-VO) containing rich bound water pathways. The in situ Raman spectra verified that these bound water pathways shield the electrostatic interaction within the lamellar [VOn] host, providing a more favourable environment for Zn2+ diffusion. The VPH-VO cathode delivered an outstanding capacity of 452 mA h g−1 at 0.5 A/g and an excellent high-rate cycling stability of 242 mA h g−1 after 2000 cycles at 10 A/g. Density functional theory calculation disclosed the highly reversible Zn2+ adsorption/desorption and low zinc-ion migration barrier in the bound water pathways of VPH-VO. This pioneering dual-vapour-thermal engineering is an efficient fabrication approach for superior lamellar cathode materials for high-performance AZIBs.