Rationalizing Functionalized MXenes as Effective Anchor Materials for Lithium–Sulfur Batteries via First-Principles Calculations

Abstract

The practical application of Li−S batteries has been greatly hindered by severe shuttle effects and sluggish kinetics. Anchoring soluble lithium polysulfides (LiPSs) onto host materials by chemisorption is an effective strategy for extending battery life. In this work, we performed systematic density functional theory calculations to evaluate the anchoring performance of O/F-covered MXene (M 2 TC 2 ) in lithium−sulfur batteries. Our results indicate that the moderate anchoring strength (∼2.5 eV), outstanding sulfur reduction performance (U L > −0.6 V), and low lithium ion diffusion barrier (<0.2 eV) of Mo 2 CF 2 and V 2 CF 2 make them promising host materials for LiPSs. We further revealed the determinants of the strength of binding of LiPSs to M 2 CT 2 . On the basis of the strong correlation among Q M , χ O/F , and E a , we established a "structure−property" equation to reveal the active origin of M 2 CT 2 . We expect that the framework established in this work will accelerate the development of Li−S batteries.

Automatic Screen‐out of Ir(III) Complex Emitters by Combined Machine Learning and Computational Analysis

“…[8][9][10][11] By comprehensively exploring the chemical space with tailored properties, HTVS succeeds in predicting the most promising candidates for experimental validation, and the trial-and-error cost can be remarkably reduced. Recent applications of this approach include the search for both organic and inorganic materials in the field of batteries, [12][13][14][15][16][17] 2D materials, [18][19][20] alloys, [21,22] semiconductors, [23,24] catalyst, [25,26] light-emitting devices, [27,28] and photovoltaics, [29,30] etc. [31][32][33][34] The central part of HTVS is the screening criteria, of which the generation relies on sufficient existing experimental data and/or accurate yet efficient quantum mechanical (QM) calculations.…”

Deciphering the Influence of Anionic Electrons of Surface-Functionalized Two-Dimensional Electrides in Lithium–Sulfur Batteries

“…The initial investigations are focused on carbon materials (of various forms), in the hope that they can offer high conductivity and physical confinement toward polysulfides to mitigate the shuttle effect . However, the interactions between nonpolar carbon and polar polysulfides are typically van der Waals forces, which are too weak to anchor the polysulfides efficiently. , Deviating from carbon materials, a variety of inorganic transition metal compounds, such as metal oxides, sulfides, nitrides, borides, selenides, and Mxenes, have also been heavily investigated. , The foremost advantage of these materials comes from their polar nature and electrocatalysis, which can afford much stronger chemical adsorptions toward polysulfides and propel the sulfur redox kinetics, respectively. Nonetheless, such a strategy is based on the complicated interplay between lithium polysulfides and host materials, and the binding strength and energy barrier to reaction essentially rely on the surface properties, active site, and local coordination environment of metal compounds. , Therefore, electron transfer plays a central role in understanding the correlation between metal compounds and polysulfides, and this inspires us to explore a new type of metal compound with electron-rich chemistry.…”

“…Mainly because of the polysulfide shuttle, Li−S batteries suffer from low capacity, poor cycling life, and low Coulombic efficiency. 13,14 Moreover, the sulfur redox reactions are sluggish in kinetics, originating from the rate-limiting step of Li 2 S deposition. This process not only involves the complicated liquid−solid phase transition but also possesses a high energy barrier that slows the reaction rate and leads to sluggish reaction dynamics.…”

“…15,16 Deviating from carbon materials, a variety of inorganic transition metal compounds, such as metal oxides, sulfides, nitrides, borides, selenides, and Mxenes, have also been heavily investigated. 14,17 The foremost advantage of these materials comes from their polar nature and electrocatalysis, which can afford much stronger chemical adsorptions toward polysulfides and propel the sulfur redox kinetics, respectively. Nonetheless, such a strategy is based on the complicated interplay between lithium polysulfides and host materials, and the binding strength and energy barrier to reaction essentially rely on the surface properties, active site, and local coordination environment of metal compounds.…”

“…The high solubility of polysulfides in electrolytes induces new concerns about their shuttle between cathode and anode, being irreversibly consumed with lithium metal, hence leading to the continuous loss of active materials of the cathode and the degradation of the lithium anode. Mainly because of the polysulfide shuttle, Li–S batteries suffer from low capacity, poor cycling life, and low Coulombic efficiency. , Moreover, the sulfur redox reactions are sluggish in kinetics, originating from the rate-limiting step of Li 2 S deposition. This process not only involves the complicated liquid–solid phase transition but also possesses a high energy barrier that slows the reaction rate and leads to sluggish reaction dynamics.…”