Engineering an Ultrathin and Hydrophobic Composite Zinc Anode with 24 µm Thickness for High‐Performance Zn Batteries

Abstract The Zn metal anode is subject to uncontrolled dendrites and parasitic reactions, which often require a big thickness of Zn foil, resulting in excess capacity and extremely low utilization. Here, an ultrathin Zn composite anode (24 µm) is developed with a protective hydrophobic layer (covalent (C 2 F 4 ) n chains and F‐doped carbonized ingredient) constructed on Cu foil (denoted as (C 2 F 4 ) n ‐C@Cu) as a host by one‐step pyrolytic evaporation deposition. The repulsion of (C 2 F 4 ) n to Zn 2+ makes the (C 2 F 4 ) n ‐C@Cu interface possess enhanced adsorption ability, driving more charge transfer under the layer. With its good hydrophobicity, this layer prevents H 2 O from damaging the plated Zn. Combined with the semi‐ionic‐state fluorine as zincophilic site, the host guides uniform and dense Zn deposition for making ultrathin Zn anode. As a result, the (C 2 F 4 ) n ‐C@Cu electrode exhibits high average CE of 99.6% over 3000 cycles at 2 mA cm −2 . Benchmarked against the commercial 20µm‐Zn foil, the (C 2 F 4 ) n ‐C@Cu@Zn anode achieves enhanced stability (1200 h at 1 mA cm −2 ), only 100 h for the 20µm‐Zn foil. When paired with V 2 O 5 cathode, the Zn composite anode makes the full cell deliver 88% retention for 2500 cycles.