Regulating Surface Overpotential for Uniform Zinc Stripping/Plating Morphology Toward Ultra‐Stable Aqueous Zinc‐Ion Batteries

Aqueous zinc‐ion batteries (AZIBs) are promising for grid energy storage owing to their low cost and high safety. However, the reversibility of the zinc anode is compromised by the uneven stripping/plating morphology and detrimental side reactions. Therefore, regulating zinc stripping/plating behavior and suppressing side reactions are pivotal for the development of AZIBs. Thermodynamic and classical nucleation theory predict that increasing the surface overpotential ( |η s | ) can reduce the critical nucleation atom number ( N crit ) and critical nucleation energy barrier ( ΔG crit ), thereby optimizing zinc stripping/deposition morphology. Herein, a trace amount of zwitterion, [2‐(methacryloyloxy) ethyl] dimethyl‐(3‐sulfopropyl) (SBMA), is introduced into 1 m ZnSO 4 as a surface overpotential regulator. SBMA molecules uniformly adsorb onto the zinc anode surface, forming an adsorption layer. This layer not only increases |η s | , but also markedly suppresses side reactions. Consequently, the stripping/deposition morphology of the zinc anode during the first cycle is significantly optimized, ensuring long‐term cycling stability. Ultimately, the Zn||Zn symmetric cell with only 1 wt.% SBMA achieves a long lifespan for over 800 h even at a high depth of discharge of 88.0%. Furthermore, the Zn||PANI (polyaniline) full cell exhibits negligible capacity decay after 1200 cycles at 1 A g −1 . This work provides valuable insights into the design of ultra‐stable AZIBs.