In Situ Molecular Self‐Assembly for Dendrite‐Free Aqueous Zn‐Ion Batteries

Abstract The large‐scale application of low‐cost and environmentally‐compatible aqueous Zn‐ion batteries (AZIBs) is largely hindered by the Zn dendrite growth stemming from inhomogeneous Zn deposition. To tackle this challenge, 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid is introduced as electrolyte additive to in situ construct ordered self‐assembled monolayers on the Zn anode (Zn@HEPES), providing uniform active sites as Zn 2+ nucleus regulators that can be dynamically and spontaneously replenished according to environmental conditions. Meanwhile, because of the regulated Zn 2+ solvation sheath and the hydrophobicity of Zn@HEPES, the direct contact between active water molecules and Zn anode is effectively ameliorated, which promotes the Zn 2+ transport and deposition kinetics. The above synergistic effects enable highly reversible Zn redox chemistry to achieve a uniform and dense Zn electrodeposition with suppressed Zn dendrite growth. Consequently, the thus‐derived Zn||Zn symmetric cells exhibit an excellent long‐term stability for 4000 h at a current density of 1 mA cm −2 . Additionally, with the aid of Zn@HEPES, the full cells coupling Zn anode and MnO 2 cathode also demonstrate superior reaction reversibility and capacity retention. This work demonstrates a distinctive avenue at the molecular level for precisely regulating the Zn electrodeposition process to achieve practical AZIBs.