Recycling of Electrode Materials from Spent Lithium-Ion Batteries to Develop Graphene Nanosheets and Graphene-Molybdenum Disulfide Nanohybrid: Environmental Benefits, Analysis of Supercapacitor Performance, and Influence of Density Functional Theory Calculations

Abstract

The development of high-performance functional nanomaterials for energy storage is now a vital task for future energy demand. In this report, a thermally reduced graphene nanosheets-molybdenum disulfide (TRGNs-MoS2) nanohybrid has been synthesized and applied for energy storage applications. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) techniques have thoroughly been used to analyze the as-prepared materials. The electrochemical performance for supercapacitor application has been demonstrated. The TRGNs-MoS2 nanohybrid material shows enhanced gravimetric capacitance values (415 F/g) with higher specific energy/power outputs and better cyclic performances (88% capacitance retention even after 5000 charging/discharging cycles). By employing density functional theory (DFT), we have presented the structure and electronic properties of the TRGNs-MoS(2)hybrid structure. The superior specific capacitance for the binary hybrid structure is supported by the enhanced electronic density of states close to the Fermi level, lower diffusion energy barrier of electrolytic ions, and higher quantum capacitance of the hybrid structure. The interaction between MoS2 and graphene is not only van der Waal's interaction but also chemical interactions that involve charge transfer from MoS2 to graphene.