Dielectric-ion-conductive ZnNb2O6 layer enabling rapid desolvation and diffusion for dendrite-free Zn metal batteries

Abstract

Rechargeable aqueous zinc-metal batteries (AZMBs) are promising candidates for large-scale energy storage systems due to their low cost and high safety. However, their performance and sustainability are significantly hindered by the sluggish desolvation kinetics at the electrode/electrolyte interface and the corresponding hydrogen evolution reaction where active water molecules tightly participate in the Zn(H₂O)₆²⁺ solvation shell. Herein, learnt from self-generated solid electrolyte interphase (SEI) in anodes, the dielectric but ion-conductive zinc niobate nanoparticles artificial layer is constructed on metallic Zn surface (ZNB@Zn), acting as a rapid desolvation promotor. The zincophilic and dielectric-conductive properties of ZNB layer accelerate interfacial desolvation/diffusion and suppress surface corrosion or dendrite formation, achieving uniform Zn plating/stripping behavior, as confirmed by electronic/optical microscopies and interface spectroscopical measurements together with theoretical calculations. Consequently, the as-prepared ZNB@Zn electrode exhibits excellent cycling stability of over 2000 h and robust reversibility (99.54%) even under high current density and depth of discharge conditions. Meanwhile, the assembled ZNB@Zn-based full cell displays high capacity-retention rate of 80.21% after 3000 cycles at 5 A g⁻¹ and outstanding rate performance up to 10 A g⁻¹. The large-areal pouch cell is stabilized for hundreds of cycles, highlighting the bright prospects of the dielectric but ion-conductive layer in further application of AZMBs.