Supercapacitors Based on Activated Carbons, Products of Rice Hull Processing

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.