Design principles of novel Zn fluorocarboxylate protection layer toward durable dendrite-free Zn metal anodes

Abstract

Aqueous Zn ion batteries (ZIBs) have received extensive attention due to their intrinsic safety, high abundance, and low cost. However, uncontrolled dendrite growth and water-induced side reactions at electrode/electrolyte interfaces hinder the advancement of ZIBs. Herein, density functional theory (DFT) calculation indicates that Zn heptafluorobutyrate can facilitate uniform Zn²⁺ deposition by leveraging the abundant zincophilic groups (e.g., –COO⁻ and –CF) and inhibit water-induced side reactions due to the presence of hydrophobic carbon chains. A Zn heptafluorobutyrate protective layer (denoted as ZFA) is constructed on the metallic Zn surface in situ by acid etching process to control Zn²⁺ desolvation and nucleation behaviors, ensuring enhanced reversibility and stability of Zn anodes. Consequently, the Zn@ZFA anode demonstrates stable operation for more than 2200 h at 1 mA cm⁻² and over 7300 cycles at 40 mA cm⁻², with high Coulombic efficiency of 99.8% over 1900 cycles at 5 mA cm⁻². Impressively, Zn@ZFA||VO₂ full cell achieves exceptional cycle life (204 mA h g⁻¹ after 750 cycles at 3 A g⁻¹) and remarkable rate performance (236 mA g⁻¹ at 10 A g⁻¹). This work provides an insightful guidance for constructing a protection layer of dendrite-free Zn anodes for high-performance ZIBs.