Figure 4 The Li electrodissolution/electrodeposition process of (a) Li-B-Mg composite and (b) pure Li foil. The SEM pictures of the Li-B-Mg composite (c) and the pure Li foil (d) after cycling 100 cycles under 2 mA·cm−2. (Reproduced from ref. [102], with permission from Copyright © 2020 The Authors. Published by WILEY-VCH.)
Additionally, constructing a 3D lithium alloy-based composites to deposit lithium has been developed. For example, our group developed a 3D silver nanowire (AgNW) and graphene-based hierarchical host (3D-AGBN)[99]. Due to the Li ions will be favorably reduced on the surface of AgNWs to form Li-Ag alloys and induce the Li depositing on the AgNW as well as the high electrical conductivity of the continuous AgNW nanonetwork can guarantee a fast and uniform electron transportation throughout the entire 3D host with low overpotential. Therefore, the Li deposition can be directed within the entire scaffold (Figure 5a) to form a smooth Li layer covering the AgNW nanonetwork after 1 mA·h·cm−2plating as shown in Figure 5b and c. Yang’s group first synthesized a 3D metal-organic frameworks derived carbon with abundant Zn clusters, after infusion the lithium, the high active nano Zn clusters could react with lithium for form the Li-Zn alloy as shown in Figure 5d[98]. Therefore, a 3D conductive carbon supported Li-Zn alloy structure has realized, which enabled the homogenization of the distributions of electric field and Li ion flux. The Li-Zn alloy layer rendered the matrix to have good affinity with lithium, and acted as a buffer layer for the following Li plating, effectively eliminating nucleation barriers. And Zhang and his co-workers proposed another kind of 3D carbon supported Li-Zn alloy structure by infiltrating lithium into carbon cloth decorated with zinc oxide arrays as shown in Figure 5e[103]. The XRD spectrum as shown in Figure 4f confirmed the formation of LiZn alloy in Li-CC@ZnO. Such a LiZn alloy formation in the Li plating process further induced dendrite-free Li deposition. As a result, a low overpotential of ~ 243 mV over 350 cycles at a high current density of 10 mA·cm−2 was achieved (shown in Figure 5f), compared to the seriously fluctuated voltage and fast short circuit in the cell using bare Li metal.