Coal-Derived Graphene/MoS2 Heterostructure Electrodes for Li-Ion Batteries: Experiment and Simulation Study.

Abstract

A novel coal-derived graphene-intercalated MoS2 heterostructure was prepared with a facile in situ hydrothermal approach followed by high-temperature calcination. XRD, FE-SEM, HR-TEM, HR-Raman, and TOC analytical instruments, combined with first-principles simulations, were employed to explore the structural and electrochemical properties of this heterostructure for use as an electrode material. The XRD measurements and simulations confirmed the formation of the MoS2/graphene (MoS2-G) heterostructure. The microstructure analysis indicated that a well-defined 3D flower-like structure with tunable interlayer distances was created in the MoS2 layer. The novel MoS2-09% G anode exhibits a remarkable initial discharge capacity of ∼929 mAh/g due to its interlayer expansion from the intercalation of graphene between the MoS2 layers. This anode maintains a capacity of ∼813 mAh/g with a Coulombic efficiency (CE) of ∼99% after 150 cycles at a constant current density of 100 mA/g. This anode also delivers a high-rate capability of ∼579 mAh/g at a current density of 2000 mA/g, significantly higher than that of other comparable structures. The unique flower-like arrangement, sufficient interlayer spacing for Li-ion diffusion, and the increased conductive matrix created using coal-derived graphene enhance the electrode kinetics during electrochemical reactions. Our first-principles calculations revealed that the diffusion barriers are significantly lower in heterostructures compared to that of bare MoS2. This heterostructure design has significant potential as a new type of anode for Li-ion storage in next-generation batteries.