Synergistic Regulation of Water Activity and Ion Transport by an In Situ‐Grown MOF/Bacterial Cellulose Separator for High‐Performance Zn Anodes

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) are promising for grid‐scale energy storage but suffer from dendritic growth and water‐induced side reactions on Zn anodes. Separator design critically regulates the electrode‐electrolyte interface, yet conventional approaches often struggle to simultaneously achieve mechanical robustness, efficient ion transport, and effective water activity regulation. Herein, we design a hybrid bacterial cellulose@UiO‐66‐NH 2 (BM) separator via in situ growth of UiO‐66‐NH 2 within a bacterial cellulose (BC) hydrogel, followed by a final hot‐pressing step, which synergistically combines the complementary properties of both components. The BC matrix confines water via hydrogen bonding, suppressing parasitic reactions, while the amino‐functionalized MOF opens up ion‐transport pathways that sieve and desolvate Zn 2 + for uniform flux. This design yields a thin (∼34 µm thick), robust (161.71 MPa tensile strength), highly porous (71.6%), and ionically conductive (3.53 mS cm −1 ) membrane. Consequently, the BM separator enables a stable Zn anode with a long cycling life of over 1000 h at 2 mA cm −2 /2 mAh cm −2 in symmetric cells and significantly improved performance in Zn||NH 4 V 4 O 10 full cells, retaining 85.32% capacity after 500 cycles at 1 A g −1 . This work presents a strategy integrating mechanical robustness with dual regulation of water state and ion transport for high‐performance AZIBs.