Homogenizing Zn 2+ Transport and Deposition by Molecular Aggregation State Regulation of Cellulose Separator for High‐Performance Aqueous Zn‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) hold great potential in grid energy storage systems, whereas the non‐uniform Zn 2+ transport within traditional expensive glass fiber separator induces severe Zn dendrite and side reactions. Herein, the molecular aggregation state is regulated by the intermolecular hydrogen bond loosening effect to prepare a robust cellulose separator for addressing the above‐mentioned challenges. By choosing ethanol as a weakly protic regenerant, the solvent regeneration process suppresses hydrogen bond reformation and guides the supramolecular aggregation of cellulose chains into a loosely packed structure. Chromogenic experiments and molecular dynamics simulations demonstrate that the separator with aggregation state regulation facilitates the uniform Zn 2+ transport and accelerates the desolvation process. This leads to a comprehensive enhancement of Zn 2 ⁺ transference number (0.61), Zn 2 ⁺ conductivity (2.87 mS cm −1 ), Zn 2 ⁺ deposition kinetics, and suppression of Zn dendrite and side reactions. Consequently, Zn||I 2 battery demonstrates a remarkable long‐term stability (exceeding 68 000 cycles) and anti‐self‐discharge performance (96.37% capacity retention after resting for 100 h). This separator also functions well in the Zn||MnO 2 battery system under high‐loading of 10 mg cm −2 . This work presents the aggregation state regulation and scalable production of low‐cost cellulose separator to facilitate the application of AZIBs.