Ultra-Dispersed α-MoC1−x Embedded in a Plum-Like N-Doped Carbon Framework as a Synergistic Adsorption–Electrocatalysis Interlayer for High-Performance Li–S Batteries

Abstract

The shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) severely hinder the scalable application of lithium-sulfurr (Li–S) batteries. Herein, the highly dispersed α-phase molybdenum carbide nano-crystallites embedded in a porous nitrogen-doped carbon framework (α-MoC1−x@NCF) are developed via a simple metal–organic frameworks (MOFs) assisted strategy and proposed as the multifunctional separator interlayer for Li–S batteries. The inlaid MoC1−x nanocrystals and in situ doped nitrogen atoms provide a strong chemisorption and outstanding electrocatalytic conversion toward LiPSs, whereas the unique plum-like carbon framework with hierarchical porosity enables fast electron/Li+ transfer and can physically suppress LiPSs shuttling. Benefiting from the synergistic trapping-catalyzing effect of the MoC1−x@NCF interlayer toward LiPSs, the assembled Li–S battery achieves high discharge capacities (1588.1 mAh g−1 at 0.1 C), impressive rate capability (655.8 mAh g−1 at 4.0 C) and ultra-stable lifespan (a low capacity decay of 0.059% per cycle over 650 cycles at 1.0 C). Even at an elevated sulfur loading (6.0 mg cm−2) and lean electrolyte (E/S is ≈5.8 µL mg−1), the battery can still achieve a superb areal capacity of 5.2 mAh cm−2. This work affords an effective design strategy for the construction of muti-functional interlayer in advanced Li–S batteries.