Ag/microcrystalline-Cu₂O composite film as an interfacial regulator for highly reversible lithium metal anode

Lithium (Li) metal is a promising anode material for high-energy-density batteries, yet its low average Coulombic efficiency (CE) results in poor cycling stability. Although significant progress has been made in addressing these issues, the stability of Li metal anode at high rates and large capacities falls short of meeting the practical application requirements. Herein, we develop a microcrystalline (MC)-Cu2O/Ag composite film on Cu current collector to regulate the interfacial properties for achieving even and dense Li deposition. The MC-Cu2O can be lithiated to form a ternary Li-Cu-O phase which possesses strong Li+ trapping capability. Besides, the MC-Cu2O can activate the electrochemical activity of Ag film, inducing a single-phase transition solid solution (alloying) reaction with high reversibility. As a result, the Ag/MC-Cu2O foam enables an even and dense Li plating/stripping behavior with high CE at a high rate and large capacity. When Ag/MC-Cu2O@Li anode is coupled with LiFePO4 cathode, the yielded full cell exhibits superior cycling stability and rate performance. Our results provide a facile approach to constructing lithiophilic current collector for a practical Li anode.