Unsaturated Amide Chemistry Enables Ultralong‐Cycling Zn Anode

Vigorous side reactions and uncontrolled Zn deposition compromise the interfacial stability of Zn anodes, severely impeding the implementation of rechargeable aqueous Zn metal batteries (RAZMBs). Developing facile and efficient strategies to mitigate these issues and achieve ultralong‐cycling Zn anodes remains challenging. Herein, an ultralong‐cycling Zn anode is realized via unsaturated amide chemistry. Specifically, amide‐based surfactants with polar groups (e.g., ─NH 2 ) and unsaturated bonds (e.g., C═C) served as electrolyte additives that specifically adsorb onto Zn anodes, reconstruct the inner Helmholtz plane (IHP) structure, and in situ form a dynamic polymer film (DPF) through electropolymerization during Zn deposition. The tailored IHP and in situ formed DPF synergistically enable a hybrid interphase integrating inorganic rigidity and organic flexibility, which not only effectively suppresses parasitic reactions, regulates Zn 2+ diffusion, and homogenizes Zn deposition, but also accommodates plating/stripping volume variations. Notably, with acrylamide (AAM) as a representative additive in ZnSO 4 ‐H 2 O electrolyte, the Zn||Zn symmetric cell delivers an ultralong cycle life of 5500 h (at 1.0 mA cm −2 and 1.0 mAh cm −2 ), outperforming most reports. These results suggest that the synergistically tailored IHP and in situ formed DPF driven by unsaturated amide chemistry can facilely and efficiently stabilize Zn anodes, providing a promising strategy for the practical application of RAZMBs.