Obtención de materiales carbonosos a partir de la cascarilla de cacao para la aplicación como electrodos en supercapacitores

Abstract

The electrochemical energy storage technologies, together with the development of materials, are promising ways to face the global challenges related to energy supply considering that global energy needs will double by the middle of the 21st century and will triple for the year 2100. Given these challenges, it is suggested the development of a high surface area carbonaceous material , using cocoa husk as precursor, an abundant lignocellulosic residue from Colombia; to develop the material, a 3^2 factorial design was used, preparing samples by impregnating the precursor with KOH at agent/solid ratios of 1:1, 3:1 and 5:1, and carbonization temperatures of 500, 650 and 800 °C; the carbonaceous materials were characterized through N2 adsorption isotherms at 77 K, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and X-ray diffraction (XRD). The specific capacitance of the samples with higher specific surface area, was determined from cyclic voltammetry experiments using 1M HCl as electrolyte and 100 mV/s scanning speed. The highest capacitance was 196 F/g, with the sample obtained at a 5:1 impregnation ratio and carbonization temperature of 650 °C; it was the sample with the highest specific surface area (1443 m2/g), the lowest ash content, the greater degree of graphitization according to Raman analysis, the more ordered structure according to the presence of graphitic signals stablished through the XRD tests, which could led to higher electrical conductivity; also, according to XPS spectroscopy, this sample had the highest proportion of C-OH and C=O bonds associated with oxygenated carboxyl, carbonyl and quinone groups, which would favor the pseudocapacitance and consequently the energy storage.