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

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 (M₂TC₂) 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 Mo₂CF₂ and V₂CF₂ make them promising host materials for LiPSs. We further revealed the determinants of the strength of binding of LiPSs to M₂CT₂. 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 M₂CT₂. We expect that the framework established in this work will accelerate the development of Li-S batteries.