S‐Doped Graphene‐Regional Nucleation Mechanism for Dendrite‐Free Lithium Metal Anodes

Abstract

hydrogen electrode). [5,6] In fact, lithium metal has been applied in space exploration, petroleum prospecting in 1970s. However, the further application of LMB is plagued with practical issues that puzzled researchers for more than 40 years. [7,8] The most critical issue is that deposition of lithium metal tends to be highly dendritic during the repeated plating and dissolution process, which not only continue to consume the electrolyte and induce the "dead lithium" leading to capacity fading, but also face the severe safety problems of short-circuit due to the crack of separator by continuous ramified growth of lithium dendrites. [9,10] During the past half-century, many up-and-coming methods have been carried out to suppress dendrite growth and achieved partially success. These strategies can be broadly divided into three areas: i) electrolyte modification (such as selfhealing electrostatic shield mechanism by inducing Cs + , [11] replacing traditional liquid electrolyte by solid state electrolyte [12] ), ii) artificial solidelectrolyte interphase (SEI) (such as manufacturing the Li 3 N, [13] LiF, [14] Li-Sn alloy [15] layers to improve the mechanical strength, ionic diffusion performance, and stability to suppress the dendrite); iii) the multifunctional nanostructured anodes design to manipulate the nucleation of lithium (such as Ni foam, [16] 3D skeleton Cu matrix, [17] Cu-Zn alloy matrix [18] ). The former two strategies are based primarily on suppressing the protrusions, while the last one mainly focuses on modulating the initial nucleation process of dendrite, before the extension of dendrites into the electrolyte. Designing the excellent LMB requires the joint effort of these methods. However, if we can eliminate or mitigate the lithium dendrite from the initial nucleation process, it will be a highly efficient and convenient measure for its industrial production. Thus, finding an ideal nucleating anode material is very important to solve the dendrite problem.Based on Chazalviel's theory, [19,20] designing high-surface area anode can suppress the local current density and thus improve the electrical performance. Graphene, who possesses very high specific surface area, shows great advantage on its potential application in lithium metal anode field. [21][22][23] However, the pristine graphene (PG) shows poor performances in the actual application. [24][25][26] Doping or modulating the graphene can adjust its performance which has already made some Lithium metal is the most promising anode material for next-generation batteries, owing to its high theoretical specific capacity and low electrochemical potential. However, the practical application of lithium metal batteries (LMBs) has been plagued by the issues of uncontrollable lithium deposition. The multifunctional nanostructured anode can modulate the initial nucleation process of lithium before the extension of dendrites. By combing the theoretical design and experimental validation, a novel nucleation strategy is developed by introducing sulfur (S) to gr...

Perpendicular MXene Arrays with Periodic Interspaces toward Dendrite‐Free Lithium Metal Anodes with High‐Rate Capabilities

“…To gain insight into the reason, the nucleation overpotentials of these composites were first measured at 0.05 mA cm −2 (Figure a). Clearly, a low overpotential of 23 mV is achieved for perpendicular MXene–Li arrays, which is only a half of the Cu–Li arrays (≈52 mV) and much lower than those of rGO–Li (≈35 mV), reported carbon and copper foams (≈38 mV) . This suggests a clear decrease of lithium plating barrier on perpendicular MXene–Li arrays, similar to our reported Li/MXene composites, owing to the large active nucleation sites of Ti–O–Li on the MXene layers (Figure S12, Supporting Information) .…”

“…The insulated 3D hosts commonly include glass fiber (GF) cloths, ZnO coated polyimide matrix, and oxidized polyacrylonitrile nanofiber networks, which can homogenize the lithium flux and enhance the transportation of lithium ions. In comparison, electrically conductive 3D hosts are common carbon nanotube sponges, Cu frameworks, reduced graphene oxide foams, 3D graphitic carbon foams, which enable to homogenize both electrical field and lithium ion flux. However, for above 3D hosts, their pores were usually disordered, far from the ideal ordered structures.…”

Interface Engineering for Lithium Metal Anodes in Liquid Electrolyte

“…Based on above concepts, various lithiophilic substrates [146][147][148][149][150][151][152] and 3D structure electrodes [153][154][155][156][157][158][159] were developed to guide uniform Li deposition and improve the interfacial stability during cycling. Zhang et al utilized unstacked graphene framework to direct uniform Li deposition (Figure 17a).…”

Recent Advances of Emerging 2D MXene for Stable and Dendrite‐Free Metal Anodes

“…[66][67][68] Improving the Wetting Ability of Substrate: The wetting ability of substrate with alkali metal plays an important role in the following uniform deposition of alkali metal. [69][70][71] A good wetting ability is able to lower the initial nucleation barrier (nucleation overpotential) of alkali metal on the substrate, resulting in a dense and dendrite-free alkali-metal deposition. [72][73][74] The wetting ability of the substrate can be improved by using seeds, modifying the surface or introducing materials that can react with alkali metals.…”