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.