Structural Engineering via In Situ Etching of Metal Surface for a Stabilized Zinc Metal Anode

Aqueous zinc-ion batteries (AZIBs) are regarded as promising candidates for next-generation energy storage systems due to their high safety, low cost, and environmental benignity. However, the practical application of AZIBs is severely hindered by uncontrollable zinc dendrite growth and parasitic reactions on the zinc metal anode during cycling. Herein, we proposed a structural engineering strategy via in situ etching of zinc metal surface using hydroxyethylidene diphosphonic acid (HEDP) to address these issues. By tuning the etching time, the proportion of (002) crystal plane on the zinc surface is significantly increased, facilitating ordered Zn²⁺ deposition. The zinc anode etched in HEDP for 30 min (30HE-Zn) exhibits the optimal electrochemical performance. Specifically, the 30HE-Zn symmetric cell achieves a stable cycle life of 5400 h at 1 mA cm^-2, and the Cu//30HE-Zn half-cell maintains stable cycling for 3600 cycles at 2 mA cm^-2 with a high coulombic efficiency of nearly 100%. When assembled with an α-MnO₂ cathode, the full-cell retains a high specific capacity of 110 mAh g^-1 after 1500 cycles at 1.5 A g^-1. In situ dendrite microscopy and ex situ characterizations confirmed that 30HE-Zn enables uniform and dense Zn²⁺ deposition/stripping, effectively suppressing dendrite formation and hydrogen evolution reaction. This work provides a facile and effective interface modification approach of zinc anodes, offering valuable insights for advancing high-performance ZIBs in the energy storage field.