Janus‐Type Electrostatic Potential Gradient‐Activated Dynamic Zn ²⁺ ‐Coordinating Nitrogen Sites in Molecularly Locked Nanocellulose Separators for Stable Zinc‐Ion Batteries

ABSTRACT Heterogeneous electric field distributions, uneven Zn ²⁺ 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 Zn ²⁺ binding affinity. The strengthened Zn‐N interactions lower the desolvation energy barrier, accelerate Zn ²⁺ 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 MnO ₂ 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.