Electrochemical Properties of Carbon Monolith from Kenaf Fibers

Carbon monoliths (CM) were prepared from kenaf fibers via moulding column-shape samples and then pyrolysis at 500, 600, 700 or 800 ^oC, followed by activation with KOH at 700 °C. Then, the samples were characterized by thermogravimetric analyser (TGA), field-emission scanning electron microscopy (FE-SEM), field-emission transmission electron microscopy (FE-TEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, x-ray diffraction (XRD) and N₂ sorption instrument. The prepared CM was subjected to electrochemical property evaluation via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The GCD study using a three-electrode system showed that the specific capacitance decreased with higher pyrolysis temperature (PYT), exhibiting the highest specific capacitance of 217 F/g with that from 500 °C pyrolysis. A two-electrode system provided 95.9 % retention upon the 5,000 cycling test as well as the specific capacitance of 212 F/g, being converted to the energy density of 6 Wh/kg at the power density of 215 W/kg.