Strong Surface‐Bound Sulfur in Carbon Nanotube Bridged Hierarchical Mo₂C‐Based MXene Nanosheets for Lithium–Sulfur Batteries

Abstract

In this work, hydroxyl-functionalized Mo₂ C-based MXene nanosheets are synthesized by facilely removing the Sn layer of Mo₂ SnC. The hydroxyl-functionalized surface of Mo₂ C suppresses the shuttle effect of lithium polysulfides (LiPSs) through strong interaction between Mo atoms on the MXenes surface and LiPSs. Carbon nanotubes (CNTs) are further introduced into Mo₂ C phase to enlarge the specific surface area of the composite, improve its electronic conductivity, and alleviate the volume change during discharging/charging. The strong surface-bound sulfur in the hierarchical Mo₂ C-CNTs host can lead to a superior electrochemical performance in lithium-sulfur batteries. A large reversible capacity of ≈925 mAh g^-1 is observed after 250 cycles at a current density of 0.1 C (1 C = 1675 mAh g^-1 ) with good rate capability. Notably, the electrodes with high loading amounts of sulfur can also deliver good electrochemical performances, i.e., initial reversible capacities of ≈1314 mAh g^-1 (2.4 mAh cm^-2 ), ≈1068 mAh g^-1 (3.7 mAh cm^-2 ), and ≈959 mAh g^-1 (5.3 mAh cm^-2 ) at various areal loading amounts of sulfur (1.8, 3.5, and 5.6 mg cm^-2 ) are also observed, respectively.