To date, various tactics have been proposed to address the above-mentioned issues, including electrolyte modification, solid state electrolyte, artificial protective layer, 3D current collector, and Li alloys. According to the Sand' time model, these strategies can be categorized as: the interlayer modification towards rapid Li
+ migration and rational stress-release; introducing functional additive in electrolyte or localized high-concentration electrolytes, to improve the quality of SEI film; anchoring lithiophilic sites to reduce the nucleation barrier for homogenous growth of Li; increasing the surface area to reduce the effective current density and retard the dendritic growth; regulating the Li
+ distribution to avoid the fast depletion of Li
+ on the anode surface [
11–
14]. Among them, the former two strategies focus on enhancing the robustness of SEI film and modifying the Li nucleation in the interface, without the whole matrix. The nucleation inside the electrode is normally uneven and SEI film would eventually crack as the accumulation of dead Li; hence, it can only restrict the Li dendrite to a limited extent. The latter ones can fundamentally solve the issues throughout the whole electrode structure, as verified by numerous reports [
15–
17]. For instance, Chi
et al. utilized a nickel foam as the conductive 3D host to obtain a composite anode of Li@Ni foam
via thermal infusion, presenting a smooth voltage pattern with considerable hysteresis over 100 cycles (200 mV, 5.0 mA/cm
2). The modulate mechanical strength of the composite anode enabled a minimum dimension change (merely ≈ 3.1%), and herein the effective inhibition of dendrite formation [
18]. However, Li metal is essentially unaffiliated to Ni foam; therefore, the nucleation barrier is relatively high, resulting in large overpotential and low CE [
19,
20]. On top of such situation, the decorations of 3D host with Li wettable components have come into the stage. Specifically, Sun's group has
in-situ chemically transformed the inert copper surface into 3D wettable Cu(OH)
2 nanowires, easily thriving a functional 3D Li@CuLi host, with the improved cyclic and rate performances [
21]. Similarly, Jiang and his collaborators applied the immersing strategy to prepare interwoven nickel(Ⅱ)-dimethylglyoxime (Ni-DMG) nanowires on nickel foam, as a robust host for Li metal anodes [
22]. In line with this, some researchers incorporated metal–organic framework-derived Co
3O
4 into nickel foam to achieve stable Li
+ storage, and the corresponding Li||Li symmetric cells can operate over 1000 h at 1.0 mA/cm
2, 1 mAh/cm
2 [
23]. Of note, the pore sizes of those conventional metal foam hosts are usually around 100 µm [
19,
24]. Therefore, despite those modification on the 3D framework can improve the lithiophilicity of metal foam to a certain extent, the broad inner voids of metal foam were filled with pure Li, whose deposition/dissolution behaviors follow the intrinsic trend, particularly for the local region far from the skeleton of metal foam. Consequently, the volume expansion and uneven nucleation would unavoidably occur, after limited cycles. Besides, the size of those
in-situ/
ex-situ decorations were relatively small (<1 µm), tending to crumble over repetitive cycling [
25–
29]. More importantly, the additional lithiophilic components were normally inferior electrotonic and ionic conductor, causing incremental internal cell resistance [
27,
30]. Hence, it is highly desirable to develop secondary network inside the macropores of metal foam, with primary requirement of considerable electronic and ionic conductivity, coupled with high lithiophilicity and relatively large size. Given this, Li-riched alloy can be a proper candidate to be a multi-functional subsidiary nest inside the metal foam, to obtain advanced composite anodes.