Janus-Type Electrostatic Potential Gradient-Activated Dynamic Zn²⁺-Coordinating Nitrogen Sites in Molecularly Locked...

Heterogeneous electric field distributions, uneven Zn²⁺ ion flux, and interfacial crosstalk typically trigger irreversible Zn redox reactions, accelerating the degradation of Zn-metal energy storage systems. Herein, we present an interfacial stabilization strategy that addresses key challenges in Zn redox chemistry through the rational design of electrostatic potential gradients within cellulose-based separators. The functionalization of cellulose nanofibrils (CNFs) with precisely arranged electron-donating polyethyleneimine (PEI) and electron-accepting benzimidazole moieties establishes a well-defined bidirectional electron transfer network. PEI-mediated electron donation to both the CNF matrix and benzimidazole ring stabilizes the surface charge environment via the interfacial dipole effect, while synergistic electron migration toward the π-conjugated benzimidazole ring increases electron density at coordination-active nitrogen sites, thereby enhancing Zn²⁺ binding affinity. The strengthened Zn-N interactions lower the desolvation energy barrier, accelerate Zn²⁺ transport kinetics, and suppress parasitic interfacial reactions, collectively enabling homogeneous Zn deposition and improved interfacial stability. Consequently, the Zn||Zn symmetric cells exhibit exceptional reversibility over 600 h at 20 mA cm^-2 and 20 mAh cm^-2. When paired with MnO₂ cathode, the full pouch cell retains 85.8% of its capacity after 4000 cycles at ∼10 C. This work highlights that molecular functionalization of separators enables next-generation aqueous Zn batteries.