Enhanced Reversible Sodium-Ion Intercalation by Synergistic Coupling of Few-Layered MoS2 and S-Doped Graphene

Sodium-ion batteries (SIBs) are regarded as the best alternative to lithium-ion batteries due to their low cost and similar Na+ insertion chemistry. It is still challenging but greatly desired to design and develop novel electrode materials with high reversible capacity, long cycling life, and good rate capability toward high-performance SIBs. This work demonstrates an innovative design strategy and a development of few-layered molybdenum disulfide/sulfurdoped graphene nanosheets (MoS2/SG) composites as the SIB anode material providing a high specific capacity of 587 mA h g(-1) calculated based on the total composite mass and an extremely long cycling stability over 1000 cycles at a current density of 1.0 A g(-1) with a high capacity retention of approximate to 85%. Systematic characterizations reveal that the outstanding performance is mainly attributed to the unique and robust composite architecture where few-layered MoS2 and S-doped graphene are intimately bridged at the hetero-interface through a synergistic coupling effect via the covalently doped S atoms. The design strategy and mechanism understanding at the molecular level outlined here can be readily applied to other layered transition metal oxides for SIBs anode and play a key role in contributing to the development of high-performance SIBs.