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

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.