Development of a Thin Three-Dimensional Ag Gradient Cu-Separator Scaffold for Stable and High-Energy Lithium Metal Batteries

Adopting three-dimensional (3D) scaffolds onto lithium metal anode has emerged as a promising strategy to improve the charge/discharge stability of next-generation high-energy-density lithium metal batteries (LMBs). However, the undesirable growth of Li dendrites on the scaffold's surface and their high-cost fabrication methods remain challenging. To address these issues, herein, a functional 3D scaffold employing a lithiophilic Ag concentration gradient (3D Ag@Cu) is designed, which can be prepared via a simple galvanic displacement. The lithiophilic Ag reacts with Li to form a solid solution, reducing the Li nucleation overpotential and promoting uniform Li deposition. Furthermore, the Ag-gradient structure facilitates the bottom-up growth of Li within the scaffold, maximizing the use of the internal space. Consequently, a full-cell equipped with the 3D Ag@Cu scaffold demonstrated higher cycling stability (89.03% capacity retention after 110 cycles) and rate performance (65.6% capacity retention at 2 C) compared to both LMBs with the planar Cu foil and the bare 3D Cu scaffold.