MoS<sub>2</sub> Nanosphere-Decorated Reduced Graphene Oxide to Promote Catalytic Activity for High-Performance Lithium–Sulfur Batteries
Zhicong Wang, Chunjuan Cui, Yanan Zhao, Haolin Li, Tongchao Wu, Zhi‐Qi Zhao, Jian Wei
Abstract
Lithium–sulfur batteries (LSBs) have been regarded as a promising rechargeable energy storage system due to their low cost, nontoxicity, and high theoretical specific capacity. The incomplete sulfur conversion and severe shuttle effect due to sluggish sulfur reduction reaction (SRR) kinetics of lithium polysulfides (LiPSs) have hindered the practical applications of LSBs for many years. Adding electrocatalysts to cathode materials to improve the conversion efficiency of polysulfides is an up-and-coming solution. As a common electrocatalyst, the catalytic capacity of two-dimensional (2D) MoS 2 is reduced due to the aggregation of nanosheets and the reduction of active sites. In this work, MoS 2 is grown in situ on graphene oxide flakes by a one-step hydrothermal method. Poly(vinyl pyrrolidone) (PVP) is added to modify the morphology of MoS 2, resulting in a three-dimensional spherical layer structure. The spherical molybdenum disulfide can better adhere to graphene flakes, providing diffusion channels for lithium-ion transfer. Moreover, smaller particle size molybdenum disulfide forms more and stronger Mo–S bonds to anchor the polysulfide, thereby the cleavage of Li–S bonds of lithium polysulfide being promoted, and S–S bonds of sulfur to accelerate the electrochemical reaction. The PVP-MoS 2 /rGO-modified Li–S battery exhibits a discharging capacity of 754 mAh/g after 200 cycles at 0.1C and a high initial capacity of 789 mAh/g at 1C. This work may provide new ideas on lithium–sulfur battery cathode materials to solve the critical issues of lithium–sulfur batteries.