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

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 Zn2+ 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.