Lithiophilic Zn–Ag alloy film-modified Cu current collector prepared by magnetron sputtering for stable lithium metal batteries

Abstract

Significant research efforts have been directed toward anode-free lithium metal batteries, primarily attributed to their exceptional energy density and low manufacturing costs. Nevertheless, significant lattice mismatch, poor lithiophilicity, and surface roughness of Cu CCs result in non-uniform lithium deposition and dendrite formation, critically undermining the cycle life and safety of the batteries. The core strategy for regulating lithium deposition/stripping behavior lies in the construction of lithiophilic interfaces or functional coatings. In this study, a highly efficient magnetron sputtering technique was employed to co-deposit a uniform and dense Zn–Ag alloy film on copper CCs. This low-temperature, large-area, and highly homogeneous process significantly reduced the lithium nucleation overpotential and localized current density, thereby promoting the establishment of a stable, inorganic-dominated solid electrolyte interphase (SEI). Experimental results demonstrated that the modified ZnAg@Cu CCs retained an average coulombic efficiency of 98.43% over 800 cycles in half-cell tests (0.5 mA cm⁻², 1 mAh cm⁻²). Furthermore, symmetric cells exhibited an ultralow voltage hysteresis of 18 mV after 3500 hours of cycling under identical conditions. Notably, full cells paired with a lithium iron phosphate (LFP) cathode achieved a 92.12% capacity retention after 100 cycles at 0.5C. This study presents an innovative solution for the interfacial engineering of current collectors for anode-free metal batteries, offering dual advantages of high-efficiency fabrication and performance optimization.