F-Free Fabrication Novel 2D Mo-Based MBene Catalyst for Advanced Lithium–Sulfur Batteries

Abstract

An efficient electrocatalytic medium is very important for lithium–sulfur (Li–S) batteries. Herein, as a novel MBene-based material, 2D MoB is employed to facilitate the catalytic conversion of lithium polysulfides (LiPSs). Instead of the HF etching technology of previous MXene, the accordion-like MoB-based MBene adopts a hydrothermal-assisted process. Its F-free surface property prevents the harm of negative sulfur cathode from −F terminations. The high charge conductivity and abundant electrocatalytic active sites promote the adsorption-transfer conversion of LiPSs on the MoB surface and accelerate the redox kinetics. Theoretical calculation, visual detection and in situ Raman results show that the stratified MoB-coated separator inhibits the “shuttle effect” of soluble LiPSs through the coupling of physical and chemical mechanisms. Therefore, this work achieves a commendable stability of 847 mAh g⁻¹ reversible capacity (2.0 C) and 0.0651% attenuation rate per cycle (4.0 C). The area capacity of 4.93 mAh cm⁻² is still obtained under high loading. More importantly, this work has uncovered the great potential of promising 2D MBene as a catalyst for the reaction of sulfur species.