Performance of Electric Double Layers Capacitor Using Activated Carbon Materials from Rice Husk as Electrodes

Abstract

Abstract Activated carbon (AC) was synthesized from rice husks using the chemical activation method with KOH, NaOH,a combination of (NaOH + Na 2 CO 3 ), and a combination of (KOH + K 2 CO 3 ) as the chemical activating reagents. The activatedcarbon with the highest surface area (around 2000 m 2 /g) and high porosity, which allows the absorption of a large number ofions, was applied as electrode material in electric double layer capacitors (EDLCs). The AC for EDLC electrodes is requiredto have a high surface area and an optimal pore size distribution; these are important to attain high specific capacitance of theEDLC electrodes. The electrodes were fabricated by compounding the rice husk activated carbons with super-P and mixed withpolyvinylidene difluoride (PVDF) at a weight ratio of 83:10:7. AC electrodes and nickel foams were assembled with potassiumhydroxide (KOH) solution as the electrolyte. Electrochemical measurements were carried out with a three electrode cell using6 M KOH as electrolyte and Hg/HgO as the reference electrode. The specific capacitance strongly depends on the porestructure; the highest specific capacitance was 179 F/g, obtained for the AC with the highest specific surface area. Additionally,different activation times, levels of heating, and chemical reagents were used to compare and determine the optimal parametersfor obtaining high surface area of the activated carbon.Key wordssupercapacitor, EDLC, activated carbons, specific capacitance, rice husk.