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

Abstract

Energy storage technologies such as electrochemical supercapacitors, require the study of new carbon materials with high surface area, high development of porosity and functional oxygen groups on their surface, to be used as electrodes with high capacitances. In this work, carbon materials were developed from cocoa husk using KOH, at three agent/solid ratios (1:1, 3:1 y 5:1 p/p) and three carbonization temperatures (500, 650 y 800 °C), in order to know the best conditions. The activated carbons were characterized by proximate analysis, N2 and CO2 adsorption isotherms; the samples with higher BET surface areas were also analyzed by Raman spectroscopy, temperature programed decomposition (DTP), and X-ray photoelectron spectroscopy (XPS), in order to determine their chemical composition, and surface structure; the electrochemical performance of these samples were evaluated by cyclic voltammetry (CV). The sample obtained at an agent/solid ratio of 5:1 and at a temperature of 650 oC showed the highest surface area, 1443 m2/g, and the highest specific capacitance of 132 F/g, presenting the lowest ash content, better development of microporosity and less disorder in its structure increasing the electrical conductivity; additionally, oxygenated groups such as carbonyl, quinones and phenols were found on its surface, and could favored the storage of energy, increasing the capacitance.