Asymmetric Zn‐N 4 Single Atom Sites Facilitate Interfacial Desolvation for Ultrafast Zinc‐Ion Storage

ABSTRACT Aqueous zinc‐ion hybrid capacitors (ZIHCs) offer a promising route to safe and low‐cost energy storage, yet their rate performance is constrained by sluggish interfacial desolvation of hydrated Zn 2+ ions and the limited electric double‐layer capacitance of carbon cathodes. Here, we introduce a dual interfacial regulation strategy that addresses both limitations through defect‐modulated Zn‐N 4 single atom sites embedded in carbon cathodes. Spectroscopic studies and theoretical calculations reveal that defect‐induced electronic asymmetry downshifts the Zn d ‐band center and generates nonbonding N/C 2 p states near the Fermi level, facilitating Zn 2+ ─H 2 O bond dissociation and accelerating interfacial desolvation. Simultaneously, enhanced electron delocalization increases surface charge density, favoring electric double‐layer formation and rapid charge accumulation. As a result, the optimized ZIHC delivers a high specific capacity of 201.5 mAh g −1 and an energy density of 146.5 Wh kg −1 , excellent rate capability (56% capacity retention at 100 A g −1 ) and long‐term durability (92.1% retention after 110,000 cycles). In situ and ex situ characterizations reveal a surface‐dominated storage mechanism involving facilitated Zn 2+ desolvation and reversible interfacial adsorption. This work establishes asymmetric single atom coordination as an effective design strategy for coupling interfacial desolvation with charge regulation in high‐rate aqueous energy storage.