Graphene and Activated Carbon Based Supercapacitor Electrodes

Supercapacitor electrodes in the monolithic form were prepared by carbonization and activation of green monoliths (GMs). The GMs and composite GMs were prepared from self-adhesive carbon grains (SACG) of oil palm empty fruit bunches and SACG added with 2 wt.% of multi-layers graphene, respectively. Both GMs and composite GMs were subjected to 18 h and 36 h milling time, respectively. The structure and porosity of the electrodes observed in the Raman spectroscopy and nitrogen adsorption-desorption results, respectively, indicated the effects of graphene addition and doubling the milling times. Galvanic charge discharge results of the supercapacitor cells fabricated using these electrodes showed that the greatest improvement due to the graphene addition occurred for the electrodes prepared based on the lower milling time. The results obtained from the electrochemical characterization showed that specific capacitance, specific power and specific energy of the cell with electrodes from the composite GMs produced from the mixture milled for 18 h were 46 F g-1, 165 W kg-1 and 1.2 W h kg-1, which were ~500 %, ~25 % and ~1100 % better than the other cells.