Fabrication of Cobalt Sulfide/Graphene Sheets Nanocomposite Harvesting Improved Anode Performance for Lithium-Ion Battery

A cobalt sulfide (CoS)/graphene sheets (GS) nanocomposite was successfully synthesized through a simple one-pot hydrothermal route assisted by ethylenediamine. The crystalline phase, structure and morphology of this nanocomposite were systematically characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen (N₂) absorption—desorption isotherm, Raman spectroscopy and thermogravimetric analysis (TGA). The results revealed that the CoS nanoparticles with size distribution of 30–100 nm were highly dispersed on or well anchored in the creasy GS substrate. Integrating nanosized CoS compound and GS outstanding merits, the as-obtained CoS/GS nanocomposite as an anode material for lithiumion battery exhibited high reversible capacity, excellent long-cycle stability and remarkable high-rate capability, which were all superior to those of pristine CoS. Moreover, this nanocomposite maintained a high capacity of ˜600 mAh·g^-1 after 200 cycles at a current density of 100 mA·g^-1. The approach presented in this work is readily applicable to nanoparticle decoration of graphene sheets and preparation of other graphene-based nanocomposites as anode materials for lithium-ion batteries.