Production of Activated Carbon Electrode for Energy Storage Application in Supercapacitors via KOH Activation of Waste Termite Biomass

Abstract

The devastating effects of termites on wood and the contribution of termite activities to the rising levels of atmospheric CO2 and CH4 constitute a serious threat to global economy and the ozone layer. In order to stall the contribution of termites to the rising levels of greenhouse gases, this work considers the conversion of termite biomass to activated carbon electrode. The waste termite biomass obtained during the production of termite biodiesel was converted to activated carbon electrode by a one-step carbonization-activation process, using potassium hydroxide as activating agent. The optimal specific surface area of the activated carbon was recorded at 900 oC, 9 h and 3:1 KOH-biomass ratio. The surface morphology and functionalization of the activated carbon were examined using the SEM, TEM, XRD, Raman and XPS characterization techniques. The electrochemical performance of the activated carbon electrode was tested in aqueous (1 M H2SO4) and ionic liquid (1 M EMImBF4) electrolytes. Results obtained from cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance experiments showed that the specific capacitance of the activated carbon electrode was higher in 1 M H2SO4 (78 Fg-1 at 0.5 Ag-1) than in 1 M EMImBF4 (53 Fg-1 at 0.5 Ag-1). However, after completing 10, 000 chare-discharge cycles at 10 Ag-1, the activated carbon electrode lost ~ 5% of its specific capacitance in 1 M H2SO4 and ~ 2% of its capacitance in 1 M EMImBF4. Overall, the results showed that waste termite biomass could be valorised in the production of activated carbon for energy storage in supercapacitors.