Functional Ultrathin Separators Proactively Stabilizing Zinc Anodes for Zinc‐Based Energy Storage

Abstract Ultrathin separators are indispensable to high‐energy‐density zinc‐ion batteries (ZIBs), but their easy failure caused by zinc dendrites poses a great challenge. Herein, 23 µm‐thick functional ultrathin separators (FUSs), realizing superb electrochemical stability of zinc anodes and outstanding long‐term durability of ultrathin separators, are reported. In the FUSs, an ultrathin but mechanically strong nanoporous membrane substrate benefits fast and flux‐homogenized Zn 2+ transport, while a metal–organic framework (MOF)‐derived C/Cu nanocomposite decoration layer provides rich low‐barrier zinc nucleation sites, thereby synergistically stabilizing zinc anodes to inhibit zinc dendrites and dendrite‐caused separator failure. Investigation of the zinc affinity of the MOF‐derived C/Cu nanocomposites unravels the high zincophilicity of heteroatom‐containing C/Cu interfaces. Zinc anodes coupled with the FUSs present superior electrochemical stability, whose operation lifetime exceeds 2000 h at 1 mA cm −2 and 600 h at 10 mA cm −2 , 40–50 times longer than that of the zinc anodes using glass‐fiber separators. The reliability of the FUSs in ZIBs and zinc‐ion hybrid supercapacitors is also validated. This work proposes a new strategy to stabilize zinc anodes and provides theoretical guidance in developing ultrathin separators for high‐energy‐density zinc‐based energy storage.