Fluoride-Based Artificial Interface for a Highly Reversible Zn Metal Anode Interlayer in Aqueous Zinc-Ion Batteries

Abstract

Zn metal is considered as one of the best anode alternatives for rechargeable aqueous zinc-ion batteries (AZIBs) due to its high theoretical capacity (820 mAh g –1 and 5855 mAh cm –3 ), low electrochemical potential (−0.76 V vs standard hydrogen electrode), abundance, and safety. However, some irreversible problems such as dendrite growth and parasitic side reactions are knotty issues that seriously affect the cycle stability and Coulombic efficiency. Here, we rationalize the design of a modified interlayer of MgF 2 nanocrystals grown on a monolayer MoS 2 substrate (MDMF) on the surface of Zn. The introduced fluorine atom plays a significant role in motivating fast Zn 2+ transfer kinetics as a zincophilic site, which can be partially converted to ZnF 2 as an artificial solid Zn 2+ conductor to further guide uniform zinc deposition. This inorganic layer successfully could induce dendrite-free Zn deposition at the interface, inhibiting Zn dendrite formation and interfacial side reactions. As a result, the MDMF@Zn anode achieved high reversibility with 99% Coulombic efficiency and long cycle stability of 700 cycles at 5 mA cm –2, demonstrating ultrastable stripping/plating behavior. In addition, the assembled MDMF@Zn//V 2 O 5 full cell showed good cycling stability (150.9 mAh g –1 after 1000 cycles at a current density of 1.0 A g –1 ) and excellent rate performance. Accordingly, the intermediate layer described in this work provides a new insight into designing stable and dendrite-free AZIBs.