Figure 5 (a) Schematic illustration of the Li plating in the 3D-AGBN host at a current density of 1 mA·h·cm−2, Magnified SEM images showing the AgNWs nanonetwork (b) before and (c) after plating 1 mA·h·cm−2 of Li in the 3D-AGBN host. (Reproduced from ref.[99], with permission from Copyright © 2018 WILEY-VCH.) (d) Schematic representation exhibits the fabrication process of Li-cMOFs. (Reproduced from ref.[98], with permission from Copyright © 2018 WILEY-VCH.) (e) Schematic fabrication process of Li-CC@ZnO electrode, (f) XRD patterns of CC@ZnO electrode before and after partial Li infiltration, and Li-CC@ZnO electrode. After Li infiltration, the original diffraction peaks of ZnO disappear, instead, (111) and (220) diffractions of Li-Zn alloy and (002) of Li2O2 appear. They are derived from the reaction of molten Li with Zn. (g) Electrochemical performance comparisons of the Li-CC@ZnO (red) and bare Li foil (black) symmetric cells. Cyclic stabilities with a Li capacity of 10 mA·cm−2. (Reproduced from ref.[103], with permission from Copyright © 2018 Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.)
Except using the 3D alloy matrix to host metallic lithium, recently researchers pay attention on various 3D Cu-alloys current collector. After the 3D Cu current collector modified by active metals, such as Al[104], Sn[101], Zn[105], Au[25], Ga-based liquid metal alloys[106], etc., it can form Li alloys after in-situ electrochemically deposition Li and then served as seeds to induce the formation of non-dendritic Li via lowering Li nucleation overpotential and interfacial energy. For example, Guo’s group reported a 3D Cu fibers grown on the Cu foil coating with a thin Al layer[104], forming a 3D Cu@Al hybrid structure; after an initial discharge process above 0 V vs. Li+/Li, the thin Al layer reacted with Li to generate a binary Li-Al alloy phase, which functioned as the lithiophilic sites. The Li nucleation and growth promoted by Li-Al alloy layer realize a dendrite-free Li anode as shown in Figure 6a and 6b. In addition, by controlling the discharge process, the active Li stored in the form of Li-Al alloy could act as a Li resource to compensate any irreversible Li loss during cycling. D. Abruña et al., reported a Zn coated Cu foil current collector[105]. During the Li plating process, the Li-Zn alloy buffer layer on the Cu foil surface would regulate the nucleation and growth of Li metal as shown in Figure 6c. As expectedly, the Coulombic efficiencies of plating/stripping was enhanced and nucleation overpotential was greatly reduced. And they also investigated the electrochemical performances of high-energy-density Li-S full cells by using the Zn coated Cu foils as Li metal current collectors. As shown in Figure 6d, the cycling stability of these two kinds of batteries was significantly enhanced.