Chitosan-assisted fabrication of ultrathin MoS₂/graphene heterostructures for Li-ion battery with excellent electrochemical performance

Graphical abstract: Display Omitted -- Highlights: •2D ultrathin MoS₂/graphene heterostructures have been prepared by a chitosan-assisted hydrothemal and a subsequent calcination method. •MoS₂ nanosheets in heterostructures are characteristic of few-layered structrues of 3–4 layers. •As an anode material for LIBs, this MoS₂/graphene heterostructure deliveres a high reversible specific capacity ∼1100 mAh g⁻¹, excellent cyclic stability and significantly enhanced rate capability (∼800 mAh g⁻¹ at 1A g⁻¹). -- Abstract: A convenient chitosan-assisted hydrothermal and postannealing strategy was successfully developed to fabricate 2D ultrathin MoS₂/graphene heterostructures. The resultant heterostructures were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption-desorption. It was found that the ultrathin MoS₂ nanosheets were of few-layered structures (3–4 layers) and were well anchored on the large flexible graphene flakes to form heterostructures, which had more uniform mesoporosity and larger surface area than the pristine MoS₂. As a result, the obtained MoS₂/graphene heterostructure electrode exhibited superior electrochemical lithium-storage performances such as high reversible specific capacity (∼1100 mAh g⁻¹), excellent cyclic stability and significantly enhanced rate capability. The prominent electrochemical performance could be attributed to the robust 2D mesoporous heterostructures composed of ultrathin few-layered MoS₂ nanosheets and highly conductive graphene as well as the resultant positive synergistic effect between them