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.