MoS₂/Graphene Composite Anodes with Enhanced Performance for Sodium‐Ion Batteries: The Role of the Two‐Dimensional Heterointerface

Abstract

Graphene has been widely used as conformal nanobuilding blocks to improve the electrochemical performance of layered metal sulfides (MoS 2 , WS 2 , SnS, and SnS 2 ) as anode materials for sodium‐ion batteries. However, it still lacks in‐depth understanding of the synergistic effect between these layered sulfides and graphene, which contributes to the enhanced electroactivity for sodium‐ion batteries. Here, MoS 2 /reduced graphene oxide (RGO) nanocomposites with intimate two‐dimensional heterointerfaces are prepared by a facile one‐pot hydrothermal method. The heterointerfacial area can be effectively tuned by changing the ratio of MoS 2 to RGO. When used as anode materials for sodium‐ion batteries, the synergistic effect contributing to the enhanced reversible capacity of MoS 2 /RGO nanocomposites is closely related with the heterointerfacial area. The computational results demonstrate that Na prefers to be adsorbed on MoS 2 in the MoS 2 /RGO heterostructure rather than intercalate into the MoS 2 /RGO heterointerface. Interestingly, the MoS 2 /RGO heterointerfaces can significantly increase the electronic conductivity of MoS 2 , store more Na ions, while maintaining the high diffusion mobility of Na atoms on MoS 2 surface and high electron transfer efficiency from Na to MoS 2 . It is expected that the efforts to establish the correlation between the two‐dimensional heterointerface and the electrochemical sodium‐ion storage performance offer fundamental understanding for the rational design of layered metal sulfides/graphene composites as high‐performance electrode materials for sodium‐ion batteries.