3D Tungsten Disulfide/Carbon Nanotube Networks as Separator Coatings and Cathode Additives for Stable and Fast Lithium-Sulfur Batteries

Abstract

Commercial application of Li-S batteries is greatly restricted by their unsatisfactory cycle retention and poor cycling life originating from the lithium polysulfide (LiPS) shuttling effect and sluggish sulfur redox kinetics. Various strategies have been proposed to boost the performances of Li-S batteries, including nanostructured sulfur composites, functional separators/interlayers, electrode/electrolyte additives, and so on. However, how to combine two or more strategies to efficiently settle these challenging issues confronted by Li-S batteries is in desperate need. Here, we demonstrate a powerful combined strategy of introducing novel 3D WS2/carbon nanotube (CNT) networks built by hybridization of 1D CNTs with 2D WS2into Li-S batteries, simultaneously serving as a functional cathode additive and separator coating. Such 3D WS2/CNTs networks with abundant edge sites, a large active surface, and a fast electron pathway twice perform functions from the cathode side and separator surface: (1) to suppress polysulfide diffusion through a physical barrier and chemical interactions; (2) to accelerate LiPS conversion reactions; and (3) to enhance conductivity for better sulfur reactivation and high utilization. As a result, the as-built WS2/CNTs-incorporated battery configuration achieves a commendable combination of capacity, rate, and cycle stability (1491 mA h g-1at 0.2 C, 754 mA h g-1at 5 C, and initial capacity of 1069 mA h g-1with an ultralow decay rate of 0.040% per cycle over 1000 cycles at 1 C) along with remarkably mitigated anode corrosion and low self-discharge.