Cu₂S Wires With Controllable Thickness on Li Foil for Stable and High-Performance Lithium Metal Anodes

Lithium (Li) metal is an attractive anode for next-generation high-energy-density batteries. However, its practical implementation is limited by interfacial instability and dendritic growth, often accompanied by high interfacial resistance. In this study, a strategy combining electrodeposition with a mechanical rolling process is presented to lower the interfacial resistance and suppress Li dendrite growth. By adjusting the current density, the thickness of Cu₂S wires is controlled at a fixed synthesis duration. A Cu foil bearing 0.32 µm thick Cu₂S wires is rolled with a Li foil, transferring the wires onto the Li surface to form Li@Cu₂S wire. During rolling, spontaneous lithiation generates a Li₂S-rich solid electrolyte interphase embedded with three-dimensional Cu dots. Li@Cu₂S wire symmetric cells exhibit stable Li plating/stripping for >3500 h at 1 mA cm^-2 and 1 mAh cm^-2. Moreover, Li@Cu₂S wire∥LiFePO₄ full cells retain more than 95% of the initial capacity for over 450 cycles at 1 C, demonstrating outstanding electrochemical performance. This work provides a simple and effective approach to enhancing Li anode performance through interfacial engineering.