Study of Active-Carbon (AC)/Graphene-Nanoplates as Supercapacitor Electrodes Using H2SO4, Na2SO4 and KOH Aqueous Electrolytes

Abstract

This thesis discuss the effect of changing the electrolyte material on active- carbon/graphene-nanoplates supercapacitor. Active-carbon/ graphene-anoplates elec-trode pellets were prepared and examined using KOH, H2SO4 and Na2SO4 electrolytes. The electrochemical characteristics (cyclic voltammetry, galvanostatic charge- discharge and electronic impedance spectroscopy) of supercapacitor were studied using a universal potentiostat/galvanostat. The specific surface area of the electrode was 951.01m2/g. This study showed that the specific capacitance achieved. a highest values of 320.3 F/g using H2SO4 electrolyte solution when measured by cyclic voltammetry method at scan rate of 5mV/s. Also, using H2SO4 electrolyte, it was found to have the lowest equivalent series resistance of 0.311 Ω using electrochemical impedance spectroscopy method. Consequently, the electrode measured using H2SO4 electrolyte has the highest specific energy and specific power of 14.82 Wh/kg and 4177.8 W/Kg, respectively. The specific energy and power were calculated using charge-discharge method. In addition, this sample was observed to have a very good cyclic staibility and efficincy when examined for a thousand cycles. Also, surface characteristics and pore size distribution were studied by brunauer- emmett- teller, brunauer-joyner-halenda and harkins-jura. Results show that active- carbon/graphene-nanoplates electrodes have a proper pore size distribution that is consistant with the ions size of H2SO4, so that this solution gives the highest specific capacitance.