Preparation of Activated Carbon from Corn Stalks by Dehydration Method as Supercapacitor Electrode Material

Porous carbon-based supercapacitors have been widely applied in the field of energy storage due to their large storage capability and physicochemical stability. However, efficient control of the microstructure of activated carbon to achieve high supercapacitor performance is still a challenge. This study used dehydration and activation methods to synthesize porous activated carbon from corn stalk waste for supercapacitor electrode applications. The preparation process was carried out through the dehydration method with 1M sulfuric acid and then activation using 5M KOH as an activator. Variations in activator mass ratio and carbonization temperature were carried out to obtain activated carbon with high surface area and pore volume. This research aims to convert corn stalk waste into active carbon material using the dehydration method, which can be used as a high-performance supercapacitor electrode. This activated carbon is used as a high-performance supercapacitor electrode material. At an activator mass ratio of 1:3 with a carbonization temperature of 800°C in a nitrogen atmosphere, activated carbon was obtained with a surface area of 396.2 m2/g,  a pore volume of 0.452 cm3/g, with a dominant micropore structure. The activated carbon material was tested via cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge cycle methods, producing a capacitance of 129.08 F/g in 3M KOH electrolyte. Moreover, supercapacitors exhibit a high energy density of 15.8 Wh/kg at power density of 2347 W/kg. This value is higher compared to activated carbon from the two-stage carbonization method. The dehydration method is an easy, environmentally friendly, sustainable, and feasible strategy for developing active carbon synthesis from biomass for green supercapacitor electrode applications.