Engineering a Gradient Zwitterionic Interphase and Dehydrated Solvation Shell for Dendrite‐Free Zn Anodes

ABSTRACT Constructing a stable solid electrolyte interphase (SEI) layer on the Zn anode is crucial for suppressing dendrite growth and side reactions in aqueous zinc‐ion storage devices. However, current SEI engineering still lacks precise control over composition, gradient structure, dynamic interface stability construction of water‐deficient solvation sheath. Here, we developed a mixed electrolyte containing N‐aminocarbonylmethyl ethanesulfonic acid (ACES), which in situ forms a dynamic zwitterionic adsorption interphase (DZAI) layer. The DZAI has a gradient structure with strong Zn‐based groups and a robust hydrogen bond network, leading to dendrite‐free, planar Zn deposition, which is consistent with a highly uniform Zn ²⁺ flux at the interface. In addition, the ACES molecules effectively reconfigure the primary solvation shell of Zn ²⁺ into a water‐deficient complex [Zn(H ₂ O) ₂ (ACES) ₄ ] ²⁺ , significantly reducing water‐induced side reactions. Therefore, the Zn||Zn symmetric battery incorporating the DZAI layer achieved excellent cycling stability of over 760 h at 50 mA cm ⁻² and 25 mAh cm ⁻² , with a cumulative electroplating capacity (CPC) of 19.5 Ah cm ⁻² . The average Coulombic efficiency (CE) of the Zn||Cu battery was also as high as 99%. Moreover, the zinc‐ion capacitors with the DZAI exhibited excellent rate performance and long‐term durability in 10 000 cycles.