Hierarchical Porous Collectors with Lithiophilicity and Conductivity Gradients for Regulated Lithium Deposition and...

Three-dimensional (3D) porous current collectors play a crucial role in mitigating volume expansion in lithium metal batteries (LMBs). However, conventional homogeneous porous current collectors are limited by the "top effect", which hinders proper regulation of lithium deposition and reduces the utilization of internal void spaces. A dual-gradient, hierarchically porous current collector (hp-CuMnZn) has been rationally designed and fabricated through a simple thermal diffusion process that induces elemental rearrangement. The top MnO layer promotes Li⁺ enrichment from the electrolyte, while its low electrical conductivity, coupled with a Zn concentration gradient, drives Li⁺ diffusion into the underlying CuMnZn alloy. This design effectively decouples Li⁺ adsorption (thermodynamic process) from reduction (kinetic process), promoting stable bottom-up Li deposition. This approach suppresses lithium dendrite growth and volume expansion, significantly improving the internal pore utilization. The half cells cycle stably for 800 cycles at high current densities, while the symmetric cells sustain long-term operation for 1300 h with a low voltage hysteresis of only 21 mV. Notably, the LiFePO₄ (LFP) full cells retain 80% capacity after 650 cycles. This work presents a practical gradient engineering strategy for developing stable, cost-effective lithium metal anodes, advancing the safe and reliable commercialization of lithium metal batteries.