L-Cysteine-Assisted Synthesis of Layered MoS2/Graphene Composites with Excellent Electrochemical Performances for Lithium Ion Batteries

Abstract

A facile process was developed to synthesize layered MoS(2)/graphene (MoS(2)/G) composites by an l-cysteine-assisted solution-phase method, in which sodium molybdate, as-prepared graphene oxide (GO), and l-cysteine were used as starting materials. As-prepared MoS(2)/G was then fabricated into layered MoS(2)/G composites after annealing in a H(2)/N(2) atmosphere at 800 °C for 2 h. The samples were systematically investigated by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. Electrochemical performances were evaluated in two-electrode cells versus metallic lithium. It is demonstrated that the obtained MoS(2)/G composites show three-dimensional architecture and excellent electrochemical performances as anode materials for Li-ion batteries. The MoS(2)/G composite with a Mo:C molar ratio of 1:2 exhibits the highest specific capacity of ∼1100 mAh/g at a current of 100 mA/g, as well as excellent cycling stability and high-rate capability. The superior electrochemical performances of MoS(2)/G composites as Li-ion battery anodes are attributed to their robust composite structure and the synergistic effects between layered MoS(2) and graphene.