Dielectric-ion-conductive ZnNb2O6 layer enabling rapid desolvation and diffusion for dendrite-free Zn metal batteries
Haifeng Yang, Jian Wang, Panpan Zhang, Xiaomin Cheng, Qinghua Guan, Jing Dong, Bixian Chen, Lujie Jia, Jing Zhang, Yongzheng Zhang, Yunjian Liu, Hongzhen Lin
Abstract
The dielectric but ion-conductive zinc niobate artificial layer is proposed to protect the Zn anode by zincophilic properties and sieving mechanism, accelerating interfacial desolvation process of [Zn(H 2 O) 6 ] 2+ for free Zn 2+ and inhibiting side reaction of active water. 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(H 2 O) 6 2+ 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.