Facile Replacement Reaction Enables Nano-Ag-Decorated Three-Dimensional Cu Foam as High-Rate Lithium Metal Anode

In developing advanced lithium (Li) metal batteries with high-energy density, excellent cycle stability, and high-rate capability, it is imperative to resolve dendrite growth and volume expansion during repeated Li plating/stripping. 3D hosts featuring lithiophilic sites are expected to realize both spatial control and dendrite inhibition over Li nucleation. Herein, this work prepares silver (Ag) nanoparticle-decorated 3D copper (Cu) foam via a facile replacement reaction. The 3D host provides rigid skeleton to accommodate volume expansion during cycling. Ag nanoparticles show micro-structural affinity to guide efficient nucleation of Li, leading to reduced overpotential and enhanced electrochemical kinetics. As the result, under an ultrahigh current density of 10 mA cm^-2, Cu@Ag foam/Li half cells demonstrate outstanding Coulombic efficiency (CE) of 97.2% more than 100 cycles. Also, Cu@Ag foam-Li symmetric cells sustain preeminent cycling over 900 h with a small voltage hysteresis of 32.8 mV at 3 mA cm^-2. Moreover, the Cu@Ag foam-Li||LiFePO₄ full cell demonstrates a high discharge capacity of 2.33 mAh cm^-2 over 200 cycles with an excellent CE up to 99.9% at 0.6C under practical conditions (N/P = 1.3, 17.4 mg cm^-2 LiFePO₄). Notably, the full cell with LiFePO₄ exhibits a higher areal capacity of 1 mAh cm^-2 over 700 cycles under a high rate of 5C, corresponding to capacity retention up to 100% (N/P = 3, 17.4 mg cm^-2 LiFePO₄). This study provides a novel and simple strategy for constructing high-rate and long-life Li metal batteries.