Rational Design of a Bilayer Interface for Long‐Term Stability of Zn Anodes and MnO2 Cathodes

Abstract Understanding the composition–characteristics–performance relationship of the electrolyte–electric double layer–electrode–electrolyte interface (EEI) is crucial to construct stable EEIs for high‐performance aqueous Zn–MnO 2 batteries (AZMBs). However, the interaction mechanisms in AZMBs remain unclear. This work introduces sodium thioctate (ST) into ZnSO 4 electrolyte to construct a stable bilayer EEI on both Zn and MnO 2 electrodes. First, zincophilic ST regulates the solvation structure of hydrated Zn 2+ , suppressing corrosion and the hydrogen evolution reaction. Second, the specific adsorption of ST reconstructs the inner Helmholtz plane, facilitating the desolvation of hydrated Zn 2+ and homogenizing charge distribution. Finally, ST molecules undergo reversible polymerization at the interface, forming a stable bilayer EEI with a poly(zinc thioctate) outer layer and a ZnS–organic amorphous inner layer, which ensures uniform zinc‐ion flux and enhances mechanical stability. Additionally, the dynamic disulfide bonds in ST further enable self‐regulation and self‐healing of the interface, mitigating damage during cycling. As a result, the ST‐enhanced Zn symmetric battery achieves 7800 cycles at 60 mA cm −2 , while the AZMB exhibits only 0.0014% capacity decay over 10 000 cycles at 2000 mA g −1 . This bilayer EEI engineering strategy offers effective guidance for the rational design of safe and long‐life aqueous zinc‐ion batteries.