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 (1588.1mAhg-1 at 0.1C), impressive rate capability (655.8mAhg-1 at 4.0C) and ultra-stable lifespan (a low capacity decay of 0.059% per cycle over 650 cycles at 1.0C). Even at an elevated sulfur loading (6.0mgcm-2 ) and lean electrolyte (E/S is ≈5.8µLmg-1 ), the battery can still achieve a superb areal capacity of 5.2mAhcm-2 . This work affords an effective design strategy for the construction of muti-functional interlayer in advanced Li-S batteries.