Spatially Distributed Lithiophilic Gradient in Low‐Tortuosity 3D Hosts via Capillary Action for High‐Performance Li Metal Anodes

Abstract

Li deposition behavior and cycling stability for Li-O 2 battery by boosting Li + transport ability. Yan et al. [33] constructed an organic/ inorganic dual-layered SEI layer to protect the Li metal anode from the corrosion of electrolytes and achieve uniform Li deposition/stripping. Xu et al. [34] proposed a stable tissue-directed/reinforced bifunctional separator to suppress the growth of lithium dendrites.However, the infinite volume variation of Li metal anode during discharge/charge processes could also cause the cracking of SEI layer and the formation of dead Li, resulting in low CE and poor cycling stability. [35][36][37][38] Designing 3D current collectors as the Li anode hosts such as 3D copper foam, [39][40][41][42] 3D carbon, [43][44][45] 3D nickel foam [46,47] have been found to be effective in relieving these challenges by providing the deposition space and diminishing the volume variation of Li metal [37,[48][49][50][51] It's worth mentioning that low tortuosity 3D current collectors, such as vertically aligned graphene oxide, [52] carbonized wood [53] and vertically aligned TiO 2 nanotubes, [54,55] have been proved to be beneficial for the fast and stable Li + transport. Unfortunately, these intricate 3D structures would result in inhomogeneous distribution of local current density and thus generate "hot spots" for Li dendrite formation on the top of 3D electrode at high current density, which significantly increases the risk of safety issues. [52][53][54][56][57][58][59] Therefore, it is highly crucial to spatially control the Li deposition far from the interface between electrode and separator in the 3D current collectors. In light of that, laminated structures with lithiophilic layers at the bottom were prepared to control the Li metal deposition at the bottom of electrode, which exhibited improved stability during the cycling processes. [10,[60][61][62] Since the lithiophilic layers would be gradually embedded in the deposited lithium during the lithium deposition process, the spatial controllability of lithium deposition for the laminated design is not ideal enough. In this regard, gradient-distributed lithiophilic sites in 3D scaffolds could be more favorable, yet synthetically challenging to achieve such unique structures.Inspired by the substances transpiration process in trees, we herein successfully achieve gradient-distributed lithiophilic sites including Ag, ZnO, and Au, in low-tortuosity 3D wood derived carbon (WDC) frameworks by a simple capillary-induced gradient deposition. Due to the merits of excellent spatial

Toward thin and stable anodes for practical lithium metal batteries: A review, strategies, and perspectives

“…The surface‐attached nitride nanoparticles provided sites for stable Li attachment and promoted uniform Li plating within the structure. The resulting C@Fe 3 N‐Li metal in the symmetric cell exhibited a low overpotential of 47 mV under a current density of 10 mA cm −2 and a capacity of 10 mAh cm −2 , operating stably for over 9000 h. In another case study, Zhu et al 51 employed a wood‐derived carbon (WDC) framework as 3D scaffolds, incorporating a lithiophilic gradient to effectively suppress Li dendrite growth and facilitate efficient Li plating within the unique porous structure (Figure 4D). Specifically, they achieved the gradient by immersing the hot WDC framework, immediately after annealing at 400°C, in a solution containing lithiophilic metal salts.…”

“…Reproduced with permission. 51 Copyright 2022, Wiley-VCH. (F) Molecular structures of various functional group coatings, (G) poor Li wettability of various metal substrates, and (H) improved Li wettability of various metal substrates after organic coating.…”

“…(E) Schematic illustration of the preparation of the 3D WDC‐GDM scaffold. Reproduced with permission 51 . Copyright 2022, Wiley‐VCH.…”

Gradient Host for Bottom-Up Deposition of Lithium Metal Anode

“…(a) Schematic diagram of the preparation of the 3D wood-derived carbon gradient hosts. [Reprinted with permission from ref . Copyright 2022, Wiley–VCH GmbH.]…”

“…130 Carbon materials and metal current collectors have grown attractive in the design of lithiophilic gradient hosts since they have been widely employed in conductive hosts. For example, Zhu et al 131 were inspired by the continuing evapotranspiration process in trees and effectively created gradiently distributed lithiophilic sites, including Ag, ZnO, and Au, in a low-distortion 3D wood derived carbon materials hosts with simple capillaryinduced gradient deposition (Figure 7a). The results show that even if the Li plating current is as high as 10 mA cm −2 , Agmodified carbon materials hosts still follow the "bottom-up" deposition pattern, and there is no Li deposition on the surface.…”