All-in-One Sulfur Host: Smart Controls of Architecture and Composition for Accelerated Liquid-Solid Redox Conversion in Lithium-Sulfur Batteries.

Abstract

The development of Li-S batteries (LSBs) is largely impeded by sluggish redox kinetics and notorious polysulfide shuttling. Herein, hierarchical MoC@Ni-NCNT arrays are reported as a multifunctional sulfur host in Li-S batteries, which comprised a flexible carbon fiber cloth substrate decorated with vertical MoC porous nanorods rooted by interconnected nitrogen-doped carbon nanotubes (NCNTs). In the designed host, the inner MoC porous backbone (composed of nanoparticles) along with the in situ-grafted interwoven NCNT shell can greatly maximize the host-guest interactive surface for homogeneous sulfur dispersion, thus realizing decent high-sulfur-loading performance. Ni nanoparticles, encapsulated within NCNTs in the outer shell, act as strong chemical-anchoring centers effectively trap-escaped polysulfides and propel the bidirectional sulfur transformation kinetics. In merit of sufficient adsorption and catalytic sites, the cell configured with the MoC@Ni-NCNT cathode delivers not only high capacity (1421 mA h g-1 at 0.1 C) but also superior rate performance and ultralong lifespan. The cell can still achieve a superb areal capacity of 6.1 mA h cm2 under an increased sulfur loading up to 6 mg cm-2. This work could open a new avenue for the construction of a multifunctional cathode for high-performance LSBs.