Rational design of graphitic-inorganic Bi-layer artificial SEI for stable lithium metal anode

Self Cite

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...

Section: Introductionmentioning

confidence: 99%

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

Wang

Zhai

Legut

et al. 2019

Self Cite

“…Similarly with lithium metal anode, Na metal batteries using conventional organic liquid electrolyte are facing some challenges, such as dendrite growth, volume changes, solid electrolyte interphase (SEI), suggesting an inferior cyclability and poor safety . Numerous efforts have been made to deal with abovementioned issues and obtain great achievements on the protection of sodium metal, such as artificial SEI, electrolyte additive, superconcentrated electrolyte, membrane modification, and 3D current collectors . Still, the inherent serious safety issues of the volatile and flammable of organic liquid electrolyte are like a sword hanging on the air.…”

mentioning

confidence: 99%

A Flexible Solid Electrolyte with Multilayer Structure for Sodium Metal Batteries

Ling

Yue

et al. 2020

111

Solid electrolytes (SEs) can potentially address the inherent safety problems of conventional organic liquid electrolytes. However, their low ionic conductivity and large interfacial resistance limit the practical applications of SEs. Here, a flexible solid electrolyte with a multilayer structure is fabricated by the UV curing of an interpenetrating network of poly(ether‐acrylate) (ipn‐PEA) in the Na3Zr2Si2PO12/poly(vinylidene fluoride‐hexafluoropropylene) porous skeleton (NZSP/PVDF‐HFP), exhibiting a high Na+ transference number of 0.63 and a suitable ionic conductivity of above 10−4 S cm−1 at 60 °C. In addition, due to the unique structure of the internal rigidity and external flexibility, the composite solid electrolyte can effectively mitigate interfacial ion transfer issues while guaranteeing a certain mechanical strength, and largely inhibiting the formation of dendrite and dead sodium. The solid sodium metal batteries using Na3V2(PO4)3 (NVP) as a cathode possess a discharge capacity of 85 mA h g−1 after 100 cycles at 0.5 C, and achieve above 90% of capacity retention rate during 100 cycles at 0.1 C for Na2/3Ni1/3Mn1/3Ti1/3O2 (NTMO) at 60 °C. The flexible solid electrolyte with multilayer structure shows a great advantage for managing the ionic conductivity and interface resistance problem, suggesting a promise as a practical sodium metal battery.

“…Moreover, the fractures of dendrites during repeated Li deposition/stripping result in "dead" Li sections composed of isolated Li fragments surrounded by e −insulating SEI. [16][17][18][19] However, because of the volume change of Li metal, the structural integrity of the protective layers is hard to be maintained during prolonged running. [15] In order to inhibit Li dendrite growth and build stable SEI layers, considerable efforts have been made.…”

mentioning

confidence: 99%

“Top‐Down” Li Deposition Pathway Enabled by an Asymmetric Design for Li Composite Electrode

Yue

Bao

et al. 2019

safety issue due to dendrite growth during the repeated Li stripping/plating process. [7][8][9] On one hand, the surface defects of the bare Li serve as the active sites to increase the local current density, leading to uneven Li deposition. [10] On the other hand, the "hostless" feature of Li metal results in huge volume change during cycling, causing unstable solid electrolyte interphase (SEI). [11] As a result, the fresh Li exposure created by SEI fracturing consumes electrolyte continuously, leading to low coulombic efficiency. [12] As such, the Li dendrites develop in an uncontrolled fashion that can eventually pierce the separator and cause short circuit. Moreover, the fractures of dendrites during repeated Li deposition/stripping result in "dead" Li sections composed of isolated Li fragments surrounded by e −insulating SEI. [13,14] The "dead" Li with high impedance leads to poor kinetics and shortened lifespan of the battery. [15] In order to inhibit Li dendrite growth and build stable SEI layers, considerable efforts have been made. One approach is the coating of an artificial SEI with high mechanical strength onto the electrode surface. [16][17][18][19] However, because of the volume change of Li metal, the structural integrity of the protective layers is hard to be maintained during prolonged running. In order to remit the volume change, great efforts have been made to design porous frameworks to accommodate Li. [20][21][22][23][24][25][26] A series of host frameworks have been reported, such as 3D CoO/Ni foam skeleton, [27] coralloid carbon fiber scaffolds, [28] lithiophilic Cu-Ni core-shell nanowire network, [29] and 3D carbon fiber framework. [30] The host frameworks can not only accommodate the volume change of Li during cycling, but also reduce the local current density. [31][32][33][34] More importantly, the porous structure of these frameworks can suppress the dendrite formation by changing Li plating/ stripping behavior. [35][36][37] It should be noted that most of the reported composited electrodes possess symmetric structure for their two sides, especially for the electrodes fabricated by thermal infusion method. [38] However, as the anode for the battery, the two sides of the electrode are in different environments: one side contacts with the separator, while the other side faces the current collector. The requirements and functions for the two sides are thus quite different. [39] The side facing the separator should be facile for Li-ion transportation.Designing Li composite electrodes with host frameworks for accommodating Li metal has been considered to be an effective approach to suppress Li dendrites. Herein, an asymmetric design of a Mo net/Li metal film (MLF) composite electrode is developed by an inverted thermal infusion method. The asymmetric MLF electrode has a dense oxide passivated layer on the top side, a porous Mo net matrix on the back side, and active Li layer in between. The back side has a larger specific area and higher electric field than the top side, which contacts with ...