2H‐MoS₂ as an Artificial Solid Electrolyte Interface in All‐Solid‐State Lithium–Sulfur Batteries

Abstract

Regardless of the battery type, Li-ion (sulfur) or Li-O 2 , it is rational to consider the lithium metal as the anode material in these batteries due to several aspects. First, it is the lightest solid (0.534 g cm −3) in the whole periodic table and has the lowest electrode potential with −3.04 V. [4,5] Second, as a pure lithium source, an intercalation or conversion reaction media is not necessarily required in batteries with lithium anodes. Overall, lithium metal has a theoretical specific capacity of ≈3860 mAh g −1. [4] However, many problems arising from the highly reactive nature of lithium metals, namely; 1) uncontrollable dendrite formation during lithium deposition\dissolution and 2) unstable solid-electrolyte interface (SEI) layer formation, restricts its use in secondary batteries. All-solid-state LIBs (ASSLIBs) are now emerging systems to replace LIBs with liquid electrolytes and are free of the aforementioned problems in certain aspects. Solid-electrolytes were shown to greatly suppress the formation of lithium dendrites. However, the formation of an unstable SEI layer still exists in ASSLIBs. Although solid electrolytes with lithium-ion conductivity on the order of liquid electrolytes have been synthesized, [6-9] their adaption into a cell with lithium anode is hindered due to the formation of unstable SEI layer. A stable SEI layer has to meet several criteria. First, an SEI layer has to be composed of electronically (ionically) insulating (conducting) phases. Besides, the layer should be thin and dense enough so that the total impedance of the system does not increase due to the low ionic conductivity of the layer. Unfortunately, only a few numbers of solid electrolytes exist that satisfies the above mentioned criteria. One plausible way to avoid the self-formation of the unstable SEI layer is to coat the lithium anode with the phases having desired properties. By coating lithium anode; 1) the contact between anode and electrolyte can be increased due to better wetting, 2) dendrite formation can be eliminated, and 3) electrolyte decomposition can be prevented. Li 3 N coating was shown to increase capacity retention in our previous study. [10] However, the small grain sizes (<160 nm), and weak interconnection is not capable of suppressing Li metal dendrites for long cycles. [11] Moreover, the voltage stability window of Li 3 N is only ≈0.45 V and unstable to reduction (≤2.4 V vs Li/Li +) which is low for practical applications. [12] An ultrathin Al 2 O 3 layer was shown to increase the wetting and electrochemical stability of the garnet-type solid All-solid-state lithium-ion batteries are considered the next-generation energy storage systems. However, certain problems arise from the degradation of anode-electrolyte interface hindering their use especially when lithium is used as an anode. Herein, lithium metal anode surface is modified by an artificial 2H-MoS 2 layer to prevent the contact between highly reactive lithium and solid electrolyte without sacrificing the lithium ion transport. The stabili...

2D Materials for All‐Solid‐State Lithium Batteries

“…By the application of MoS 2 , the ASSLBs exhibits 675.8 mA h g −1 initial capacity and 584.1 mA h g −1 final capacity at 0.4 mA cm −2 , and after 200 cycles, MoS 2 ASSLBs fade by 13.58%, while ASSLBs without MoS 2 fade 27.3% (Figure 4e). [127,128]…”

“…e) Cycling performance of Li|MoS 2 / Li 7 P 3 S 11 |S cell. Reproduced by permission [127]. Copyright 2019, Wiley-VCH.…”

Will Sulfide Electrolytes be Suitable Candidates for Constructing a Stable Solid/Liquid Electrolyte Interface?

“…53 Additionally, defects such as grain boundaries, pores and cracks facilita te the growth of lithium dendrites. 54 The lithium penetration issue has been demonstrated to be ameliorated by engineering interlays between lithium and solid electrolytes, [55][56][57] and by improving the density of the solid electrolyte. 58 In our case, the coexistence of liquid and solid electrolytes as well as the in-situ formed solvated interphase layer even complicate the properties of the interface with the lithium anode, make it complex to The stability is also illustrated by the little change of the impedance spectra of the cells after 100 h operation (Figure 2b-d).…”

Recent Progress in High‐Performance Lithium Sulfur Batteries: The Emerging Strategies for Advanced Separators/Electrolytes Based on Nanomaterials and Corresponding Interfaces

“…modified lithium metal anode surface by an artificial 2H‐MoS(2)layer to prevent the contact between highly reactive lithium and solid electrolyte without sacrificing the lithium ion transport. By stabilizing electrode/electrolyte interface, initial and final discharge capacities of 675.8 and 584.1 mAh g −1 , respectively, is obtained at 0.4 mA cm −2 current density in MoS2@Li/Li7P3S11/S [140] . Nan et al.…”