A route to synthesis molybdenum disulfide-reduced graphene oxide (MoS₂-RGO) composites using supercritical methanol and their enhanced electrochemical performance for Li-ion batteries

A simple and effective approach for the tight anchoring of molybdenum disulfide (MoS₂) to the surface of supercritical-alcohol-reduced graphene oxide (SRGO) is developed. The MoS₂-SRGO composites are synthesized by the one-pot deposition of MoO₂ on SRGO and simultaneous reduction of GO to SRGO in supercritical methanol followed by sulfurization. The obtained MoS₂-SRGO composites contain a crystalline MoS₂ phase comprising 11-14 layers of MoS₂. In addition, the composites have mesoporous structures with high porosities, ranging between 55 and 57%. In comparison with bare MoS₂ and SRGO, the MoS₂-SRGO composites have enhanced electrochemical performances due to their mesoporous structures and the synergetic effect between MoS₂ and SRGO sheets. When tested as the anode in a secondary lithium battery, it shows high reversible capacity of 896 mAh g^-1 at 50 mA g^-1 after 50 cycles, a high rate capacity of 320 mAh g^-1 at a high charge-discharge rate of 2.5 A g^-1, and long-term cycling of 724 mAh g^-1 at 50 mA g^-1 after 200 cycles. This unique synthetic approach effectively and tightly anchors MoS₂ nanoparticles to the SRGO surface, resulting in improved structural integrity, electron transfer efficiency between the SRGO sheets and MoS₂, and Li-ion diffusion kinetics.