Dual-Gradient 3D Porous Alloy Current Collectors To Guide Ultrauniform Lithium Deposition in Lithium Metal Batteries

Three-dimensional (3D) porous current collectors are regarded as promising candidates to disperse current density, suppress lithium dendrite growth, and provide space for lithium deposition to mitigate volume expansion in lithium metal batteries. Nevertheless, due to the "top effect", lithium tends to preferentially deposit on the upper surface during cycling, instead of on inner pores, which results in inefficient porosity utilization and compromised energy density. Herein, a dual-gradient 3D porous CuMnZn current collector (DG-CuMnZn) is developed through a facile annealing-etching approach, featuring both elemental and structural gradients to guide uniform bottom-up lithium deposition. The dual-gradient design effectively modulates both the lithiophilic distribution and the current density gradient within the current collector, enabling precise control over the lithium metal deposition pathway. The experimental results demonstrate a high internal space utilization efficiency of up to 70%, even for the submicrometer pores (≤1 μm) within current collectors. When paired with the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode in a full cell at a low negative/positive (N/P) ratio of ∼1.43, the DG-CuMnZn current collector demonstrates excellent long-term cycling stability. The DG-CuMnZn as a promising current collector, characterized by cost-effectiveness, scalable fabrication, and ease of recycling after failure, holds significant commercial application potential.