Promoting polysulfide redox kinetics by Co9S8 nanoparticle-embedded in N-doped carbon nanotube hollow polyhedron for lithium sulfur batteries

Abstract

Lithium-sulfur (Li-S) battery is one of the most promising candidates for next-generation rechargeable batteries, while the volume expansion, severe shuttle effect, and sluggish reaction kinetics hinder its practical applications. Herein, a novel structure composed of Co9S8 nanoparticles embedded in a N-doped carbon nanotube hollow polyhedron (Co9S8@NCNHP) is designed to address these issues. Co9S8 nanoparticles can efficiently accelerate the kinetics of redox reaction and anchor the polysulfides, enhancing the electrochemical performance of cathodes. Furthermore, NCNHP can accommodate the huge volume expansion and block the diffusion of lithium polysulfides. Benefiting from this rational design, the Co9S8@NCNHP/S cathode exhibits a high initial discharge capacity of 1186 mAh·g−1 with a decay rate of 0.1% per cycle during 200 cycles at 0.2 C. An initial discharge capacity of 780 mAh·g−1 as well as a decay rate of 0.15% per cycle after 200 cycles can be obtained at a sulfur loading of 3.2 mg·cm−2. This strategy based on the combination of rational structure design and electrocatalysis could advance the cathode construction in Li-S batteries.