Self-Formed Lithiophilic Alloy Buffer Layer on Copper Foam Framework for Advanced Lithium Metal Anodes

The hostless nature of a lithium metal anode leads to dendrite growth and dimension change, which severely restrict the application of rechargeable lithium metal cells. Optimization design for the anode structure that changes the nature from hostless to host may provide an effective way to address this issue. In the present study, we report a simple and cost-effective strategy for the construction of a phase-segregated structure for stable lithium metal anodes. Taking advantage of the strong interaction between the Mg atom and the Cu slab at the solid (Cu)–liquid (Li–Mg alloy) interface, the Cu–Cu2Mg–Li phase-segregated structure was spontaneously shaped during the process of thermal infusion followed by cooling. The surface of the stable three-dimensional distributed conductive Cu skeleton was modified by Cu2Mg to form a phase-segregated structure, which afforded uniformly and stably distributed active sites with a large specific surface area that can reduce and homogenize the Li+ flux. Consequently, the composite Li electrode with this structure showed a good electrochemical property, performing stably for over 1200 cycles at a high current density of 5 mA cm–2 with an areal capacity of 1 mA h cm–2 in a constant current test of symmetrical cells, and a 96.3% capacity retention was maintained after 500 cycles in full cells with LiFePO4 at 0.5 C.