Reconfiguring Zn²⁺ Solvation Structures and Modulating the Inner Helmholtz Plane Via Janus Supramolecules

Abstract Zn metal anodes (ZMAs) are plagued by dendritic growth and side reactions, which results in the degradation of their electrochemical performance. In this study, a carboxylated pillar[5]arene (CP5) is introduced with Janus properties to reconstruct the solvation structure of Zn²⁺ and modulate the inner Helmholtz plane (IHP). The electron‐rich cavity of CP5 adsorbs Zn²⁺ through electrostatic interactions synergistically reconfiguring the solvated structure of Zn. Concurrently, the zincophilic carboxyl groups preferentially adsorb onto the Zn electrode interface, while the hydrophobic cavity modulates the IHP by repelling certain H₂O molecules. The synergistic impact of this dual reconfiguration strategy effectively suppresses the hydrogen evolution reaction (HER), and curtails dendrite formation and associated side reactions, thereby enhancing the long‐term stability of the electrode‐electrolyte interface. The results demonstrate that a Coulombic efficiency (CE) of 99.1% in the Zn||Cu asymmetric cell is achieved during the galvanization/stripping process at 5 mA cm⁻² under 1 mAh cm⁻². Furthermore, the optimized electrolyte maintains a capacity retention of 91.4% after 1000 cycles in a Zn‐I₂ battery, demonstrating exceptional cycling stability. This study offers a viable strategy for optimizing the Zn²⁺ solvation structure and informs the design of electrolytes for highly reversible metal‐anode batteries.