MoS2-Modified N-Doped Graphene/Organosulfide Composite Cathode Material for High-Performance Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) possess merits of high theoretical specific capacity, high energy density, abundant resource, and low cost, making them promising candidates for future energy storage systems. Although numerous advanced high-performance LSBs have been studied, their further development still faces severe challenges. The redox intermediate lithium polysulfides (LiPSs) can be easily soluble in electrolytes and shuttles to anodes through a separator, leading to continuous loss of cathode-active materials and side reactions with lithium anodes, thereby compromising cycling stability. In addition, the sulfur cathode and its discharge product Li₂S exhibit poor electronic conductivity and undergo substantial volumetric changes during the discharge/charge process, affecting reaction kinetics and cycle life. To address these challenges, we developed an integrated system combining a MoS₂-modified N-doped graphene host material (MoS₂–NG) with an organosulfide-active material (S-SH), yielding a composite cathode material (MoS₂–NG@S-SH) with multiple advantages. The porous carbon-based MoS₂–NG host material, containing various heteroatoms, provides improved electronic conductivity, volume change buffering, physical barriers, chemical adsorption, and catalytic sites for LiPSs, synergistically suppressing the shuttle effect and facilitating the reaction kinetics. Furthermore, the S-SH active material features stable chemical bonds, contributing to enhanced cycling stability. Consequently, the MoS₂–NG@S-SH cathode delivers a high specific capacity of 1573.8 mA h g^–1 at 0.05 C and maintains an exceptional average retention of 99.94% per cycle after 500 cycles at 1.0 C, demonstrating superior electrochemical performance.