A hydrophobic-zincophilic bifunctional interface enables stable Zn metal anode

Aqueous zinc-ion batteries (ZIBs) are promising next-generation energy storage systems due to their inherent safety. However, the challenges including "dead zinc" accumulation, low depth of discharge (DOD), and severe side reactions impede their wide development. To address these issues, a hydrophobic-zincophilic Cu(OTf)2 layer is anchored on Cu foil through strong coordination adsorption. The Cu(OTf)2 can minimize aqueous side reactions via hydrophobic C-F, and provide the nucleation sites for uniform zinc deposition by the electrostatic interaction of sulfonic acid group and Zn2+ ion. A precisely pre-deposited zinc anode (Zn@Cu-OTf) is fabricated via controlled electrodeposition, which reduces the excess zinc consumption and enhances the performance at a higher DOD. As a result, the Zn@Cu-OTf symmetric cell maintains stable cycles for 724 h at 2 mA cm-2 with 40% DOD. The Cu-OTf//Zn half-cell achieves uniform zinc deposition/stripping, with a Coulombic efficiency of 99.7% over 1400 cycles. Moreover, the Zn@Cu-OTf//MnO2 full cell retains 69.4% of capacity after 500 cycles at 1 A g-1 and demonstrated an outstanding rate capability. This work validates the effectiveness of hydrophobic-zincophilic interface layer in improving the reversibility and durability of zinc anodes.