Built-In Catalysis in Confined Nanoreactors for High-Loading Li-S Batteries.

Abstract

A cathode host with strong sulfur/polysulfide confinement and fast redox kinetics is a challenging demand for high-loading lithium-sulfur batteries. Recently, porous carbon hosts derived from metal-organic frameworks (MOFs) have attracted wide attention due to their unique spatial structure and customizable reaction sites. However, the loading and rate performance of Li-S cells are still restricted by the disordered pore distribution and surface catalysis in these hosts. Here, we propose a concept of built-in catalysis to accelerate lithium polysulfide (LiPSs) conversion in confined nanoreactors, i.e., laterally stacked ordered crevice pores encompassed by MoS2-decorated carbon thin layers. The functions of S-fixability and LiPS catalysis in these mesoporous cavity reactors benefit from the 2D interface contact between ultrathin catalytic MoS2 and conductive C pyrolyzed from Al-MOF. The integrated function of adsorption-catalysis-conversion endows the sulfur-infused C@MoS2 electrode with a high initial capacity of 1240 mAh g-1 at 0.2 C, long life cycle stability of at least 1000 cycles at 2 C, and high rate endurance up to 20 C. This electrode also exhibits commercial potential in view of considerable capacity release and reversibility under high sulfur loading (6 mg cm-2 and ∼80 wt %) and lean electrolyte (E/S ratio of 5 μL mg-1). This study provides a promising design solution of a catalysis-conduction 2D interface in a 3D skeleton for high-loading Li-S batteries.