In Situ Generation of Co-Decorated Carbon Nanotubes by Zeolitic Imidazolate Frameworks to Facilitate High-Performance Lithium–Sulfur Batteries

Abstract

Lithium−sulfur (Li−S) batteries are perceived as a promising energy storage system for the next generation because of the advantages of high theoretical specific capacity and environmental friendliness. Whereas, challenges such as the poor conductivity of sulfur, the "shuttle effect" of polysulfides, and the sluggish redox kinetics of polysulfides in conversion reactions remain. Herein, the cubic shape of ZIF−67 was prepared, and Co-decorated carbon nanotubes covered on the nitrogen−carbon matrix (CoNC−CNT) and CoNC−CNT coated with reduced graphene oxide (CoNC−CNT/rGO) hybrids are obtained by using cubic ZIF−67 as raw material. The compounds are proposed as the sulfur carrier matrix of Li−S batteries to promote electrochemical performance. The porous three-dimensional (3D) conductive network provides physical confinement, and Co nanoparticles provide chemical adsorption and catalysis for polysulfides. The CoNC−CNT/S hybrid delivers a reversible highcapacity of 1267.2 mAh g −1 at 0.05C and 509.4 mAh g −1 even under 4C. The CoNC−CNT/rGO/S electrode exhibits an outstanding long-term cycle stability with the decay rate of 0.0516% per cycle. This study combines physical confinement, chemical adsorption, and catalysis strategies to obtain high-performance Li−S batteries.