Interface regulation using a fluorinated vinylene-linked covalent organic framework for a highly stable Zn anode

Abstract

For aqueous zinc-ion batteries, comprehensively optimizing the Zn/electrolyte interface microenvironment is an effective strategy to avoid harmful side reactions and Zn dendrites and thus helps to achieve a high-performance Zn anode. Herein, a functional vinylene-linked covalent organic framework with zincophilic fluorinated sites (TM-4F-COF) is well designed and applied as an interface layer, which modifies the chemical microenvironment at the Zn/electrolyte interface to simultaneously manipulate the Zn plating/stripping behaviors and interfacial side reactions. The TM-4F-COF layer can accelerate Zn²⁺ de-solvation and interfacial Zn²⁺ transfer due to the abundant zincophilic fluorinated sites, consequently facilitating the formation of a uniform Zn²⁺ re-distribution layer. Furthermore, an even electric field is realized at the TM-4F-COF/Zn interface due to the conjugated structure of TM-4F-COF, and the preferentially formed Zn(002) results in a horizontally dense Zn deposition to provide dendrite-free features and high reversibility. A TM-4F-COF@Zn symmetrical cell exhibits an ultra-long cyclability of 2935 h at 3 mA cm⁻². Our work provides a fundamental strategy to fabricate a stable Zn anode for high-performance aqueous zinc-ion batteries.