Electrochemical Studies on Corncob Derived Activated Porous Carbon for Supercapacitors Application in Aqueous and Non-aqueous Electrolytes

Corncob carbon prepared by means of (KOH) chemical activation method at 600 °C for 1 h is shown as a promising electrode material for supercapacitors. The XRD analysis of the activated corncob carbon shows highly amorphous and disordered structure. The specific surface area and pore volume of the activated carbon are analysed using Brunauer-Emmett-Teller (BET) method. The calculated BET surface area of activated corncob carbon is ∼ 800 m² g⁻¹ with micro and mesoporous in nature. The porous nature of the carbon is further confirmed using SEM and HR-TEM analysis. The electrochemical studies in aqueous electrolytes reveal that a high specific capacitance of 390 F g⁻¹ at 0.5 A g⁻¹ current density. The electrochemical performance of activated corncob electrodes is studied in three different ionic liquids, among them the EMIMBF₄ possess good capacitive behaviour and the wide potential window resulted a high energy density of 25 Wh kg⁻¹ and power density of 174 W kg⁻¹. The supercapacitor device fabricated using the ionic liquid could power a red LED for more than 4 min after upon 10 s charging. The above investigation clearly indicates that the corncob derived carbon materials are promising for applications in supercapacitor.