Chelation‐Driven Functional Janus Interface Remodeling Electric Double Layer for Highly Reversible Aqueous Zinc‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) are considered promising candidates for energy storage due to their high safety and theoretical capacity. However, their large‐scale application is still hindered by several interfacial issues, such as hydrogen evolution, zinc corrosion, and inhomogeneous deposition. Here, a molecular‐level electrolyte regulation strategy is realized by introducing trace amounts of 2,2′‐bipyridine (Bpy), a prototypical bidentate chelating agent. The strong coordination between Bpy and Zn 2+ facilitates the formation of stable five‐membered chelate rings, driving the preferential adsorption of Bpy to dynamically restructure the electric double layer (EDL) and construct a functional Janus interface. This unique configuration decouples ion transport from parasitic solvent interactions: the hydrophobic aromatic backbone creates a potent water‐repellent barrier to suppress the hydrogen evolution reaction and corrosion, while the chelation‐active nitrogen sites ensure accelerated Zn 2+ transport kinetics. Consequently, the regulated electrolyte delivers an ultralong lifespan up to 3500 h in Zn||Zn symmetric cells and a high Coulombic efficiency of 99.6% in Zn||Cu cells. Full‐cell evaluations further demonstrate extended cycling stability and suppressed self‐discharge, highlighting the effectiveness of this chelation‐governed interfacial regulation strategy for advancing practical AZIBs.