In situ N-doped CoS2 anchored on MXene toward an efficient bifunctional catalyst for enhanced lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries with high theoretical energy and power density offer a potential alternative for the development of electric vehicles and other applications. However, it suffers from the shuttle effect of lithium polysulfides (LiPSs) and sluggish chemistry reaction kinetics. Herein, a novel N-doped MXene-CoS2 (denote as N-MX-CoS2) nanohybrid is developed by a one-step in situ sulfidation strategy. Owing to the synergistic chemisorption of dopant nitrogen sites and polar CoS2 nanoparticles, such nanohybrid ensures a high ability to adsorb LiPSs. The highly electrical conductivity of MXene substrate with an extended layered structure facilitates fast sulfur electrochemistry redox reaction. We provide a strategy for rational design and fully explore its synergy as an efficient bifunctional heterostructure, which achieves the “all-in-one” results. Consequently, the deliberately designed bifunctional nanohybrid achieves effective LiPSs immobilization and conversion, which address the deficiencies for Li-S batteries. The cell with N-doped MXene-CoS2 modified separator exhibits high initial specific capacity (1031 mAh g−1 at 1 C), outstanding rate performance, and cycle stability (with a low decay rate of 0.052% per cycle at 1 C).