The Organic Ligand Etching Method for Constructing In Situ Terraced Protective Layer Toward Stable Aqueous Zn Anode

The stability of aqueous Zn-ion batteries (AZIBs) is highly dependent on the reversibility of stripping/plating Zn anode. In this work, an organic ligand etching method is proposed to develop a series of in situ multifunctional protective layers on Zn anode. Particularly, the 0.02 m [Fe(CN) 6]^3- etching solutions can spontaneously etch the Zn anode, creating an in situ protective layer with unique terraced structure, which blocks the direct contact between the electrode and electrolyte and increases the area for Zn²⁺ ions deposition. Interestingly, all elements in the organic ligands (i.e., C, N, Zn, and Fe) exhibit strong zincophilic, significantly promoting zinc deposition kinetics and enhancing 3D nucleation behavior to inhibit zinc dendrite growth. As a result, the etched Zn anode can provide as high a Coulombic efficiency of 99.6% over 1000 cycles and sustain over 400 h long-term stability at a high current density of 10 mA cm^-2 . As general validation, the small amount of metal cations additives (e.g., Ni²⁺ , Mn²⁺ , and Cu²⁺ ) can accelerate the synthesis of artificial interface layers with 3D structures and also regulate zinc deposition behavior. This work provides a new idea from the perspective of etching solution selection for surface modification of Zn metal anode.