Prevention of sulfur diffusion using MoS₂-intercalated 3D-nanostructured graphite for high-performance lithium-ion batteries

We report new three-dimensional (3D)-nanostructured MoS₂-carbonaceous materials in which MoS₂ sheets are intercalated between the graphite layers that possess a multiply repeated graphite/MoS₂/graphite structure which prevents the aggregation of MoS₂ and diffusion of sulfur from carbonaceous materials, enhancing the cycling stability of Li-ion batteries. We developed an efficient and scalable process applicable to mass production for synthesizing non-aggregated MoS₂-intercalated 3D hybrid-nanostructured graphite based on stress induced and microwave irradiation. X-ray diffraction, X-ray photospectroscopy, Raman spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy analyses demonstrated that the as-synthesized materials consisted of MoS₂-intercalated 3D hybrid-nanostructured graphite platelets that had a multiply repeated graphite/MoS₂/graphite structure. The obtained MoS₂-graphite powder surpasses MoS₂ as an anode material in terms of specific capacity, cyclic stability, and rate performances at high current densities for Li-ion batteries. The electrochemical impedance spectroscopy demonstrated that the graphite sheets not only reduced the contact resistance in the electrode but also facilitated electron transfer in the lithiation/delithiation processes. The superior electrochemical performances especially for the cycling stability of the Li-ion battery originate from prevention of the sulfur diffusion of the MoS₂-intercalated 3D-nanostructured graphite.