MoS2/Graphene Hybrid Nanoflowers with Enhanced Electrochemical Performances as Anode for Lithium-Ion Batteries

Abstract

In this work, we studied the synthesis and electrochemical performance of MoS2 and reduced graphene oxide (rGO) hybrid nanoflowers for use as anode material in lithium ion batteries (LIBs). The morphology and microstructure of the samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrometry (XPS). Herein, the composite nanoflowers delivered a significant enhanced reversible specific capacity and charge/discharge cycle stabilities as anode in comparison with pristine MoS2. Electrochemical impedance spectroscopy (EIS) measurements indicated that the incorporation of rGO significantly reduced the contact resistance and the improved electrochemical performances could be attributed to the synergy effect between the functions of MoS2 and rGO. A high reversible capacity of 1150 mAh/g at a current of 0.1 A/g could be retained without fading after 60 cycles. The rate performance of the composite was also improved, and the specific capacity remained at the relative high value of ∼890 mAh/g even at a current of 1 A/g. In order to further systematically study the mechanism of the improved LIBs performances for composite, we constructed the corresponding models based on experiment data and conducted a first-principles calculation. The nudged elastic band (NEB) method was employed to study the diffusion of Li in different structures. The calculated results proved that the diffusion barrier for Li in MoS2/graphene was significantly lower than that in pristine MoS2 and presented a theoretical explanation for a better diffusivity property. The high specific capacity and excellent cycling stability of these hybrid nanoflowers are competent as a promising anode material for high-performance LIBs.