Improving the Anode Performance of WS2 through a Self-Assembled Double Carbon Coating

Tungsten disulfide, which possesses a well-defined layered structure, has been intensively studied as an anode material for lithium ion batteries, but it usually suffers from poor cycling stability because of its large volume changes during lithium insertion and extraction processes. Herein, we develop a self-assembled double carbon coating to enhance the anode performance of WS2 via a self-assembly process between oleylamine-coated WS2 nanosheets and graphene oxide and subsequent pyrolysis treatment. When employed as an anode material for lithium ion batteries, the as-prepared WS2@C/reduced graphene oxide (WS2@C/RGO) composite exhibits excellent cycling stability and rate capability when compared to WS2@C nanosheets. A reversible capacity of 486 mA h g–1 and around 90% capacity retention were obtained after 200 cycles at a current density of 0.5 A g–1. Even under 10 A g–1, a high reversible capacity of 126 mA h g–1 can be retained. The good electrochemical performance could be attributed to the external electronically conductive and flexible RGO coating in addition to the surface carbon layer and the uniform distribution of WS2 nanosheets. The self-assembled dual carbon coating strategy is facile yet effective, and it may be applied to other high-capacity anode materials with huge volume changes and poor electrical conductivities.