Síntese de grafeno por moagem de alta energia para aplicação em supercapacitores

Abstract

Supercapacitors are small devices with the function of storing high amounts of energy for certain electrical functions, for such performance the graphene proves to be an ideal candidate to perform this function due to its high density of power and energy and stability in long cycles of charge and discharge. The method of obtaining graphene passes through the technique of high energy ball milling, due to the versatility of the technique, allowing the exfoliation of the graphite in graphene for a large-scale production of the material. The graphite samples passed through progressive hours of milling, starting from the manually macerated graphite and then 2, 4, 8, 12 hours of milling. The samples were analyzed structurally by X-Ray diffraction, showing the evolution of the crystalline phases present in the material. Raman spectroscopy for quantitative and qualitative monitoring of graphene layers, related to the appearance of the "D" and "G" bands and their harmonics in the "2D" region and Ultraviolet Spectrophotometry and Scanning Electron Microscopy to follow the structural changes after each milling process. The electrochemical behavior of the samples was measured by Cyclic Voltammetry, Galvanostatic Charge and Discharge, Electrochemical Impedance Spectroscopy, Electrochemical Stability. The electrochemical analysis showed the relationship between the structural modification of the material through the exfoliation process and its electrochemical behavior, indicating that the graphene exfoliated from the graphite flake reaches a specific capacitance of 274.75 F.g-1, with an energy density of 952.38 Wh.Kg-1 and a power density of 152.62 W.Kg-1 indicating that high energy ball milling may be a synthetic route for the application of graphene multilayer in supercapacitors.