Ultrathin sandwich-like MoS₂@N-doped carbon nanosheets for anodes of lithium ion batteries

In this work, we report on a simple and scalable process to synthesize the core-shell nanostructure of MoS₂@N-doped carbon nanosheets (MoS₂@C), in which polydopamine is coated on the MoS₂ surface and is then carbonized. An intensive investigation using transmission electron microscopy and Raman spectroscopy reveals that the as-synthesized MoS₂@C possesses a nanoscopic and ultrathin layer of MoS₂ sheets with a thin and conformal coating of carbon layers (∼3 nm). The MoS₂@C demonstrates a superior electrochemical performances as an anode material for lithium ion batteries compared to exfoliated MoS₂ and bulk MoS₂ samples. This unique core-shell structure is capable of delivering an excellent Li⁺ ion charging-discharging process as follows: a specific capacity as high as 1239 mA h g^-1, a high rate capability even at a high current rate of 10 A g^-1 while retaining 597 mA h g^-1, and a good cycle stability over 200 cycles at a high current rate of 2 A g^-1.