Supercapacitors Based on Activated Carbons, Products of Rice Hull Processing

Abstract

Rice hull ash (RHA) produced commercially by burning hulls of rice growing in the Krasnodar Krai, Russia, is characterized by a series of modern physicochemical investigation methods. The RHA is shown to contain amorphous silica (>70 wt %) and carbon (~8 wt %). Activated carbon (AC) is prepared by treating RHA with an alkali solution followed by annealing at 700°C. The specific surface area of AC is 1442 m2 g–1, with mesopores dominant in its structure. The AC is used as an electrode material in fabricating electric double-layer supercapacitors containing an aqueous 6 M KOH electrolyte or an organic 1 M Et4NBF4/PC electrolyte. The energy storage capacity of studied EDLCs are 299 and 131 F g–1, respectively.