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

• Published in: Electrochimica acta 2017-02, Vol.228, p.586-596
• Main Authors: Karnan, M., Subramani, K., Srividhya, P.K., Sathish, M.
• Format: Article
• Language: English
• Subjects: Activated carbon; Amorphous structure; Aqueous electrolytes; bio-derived; Carbon; corncob; Current density; Density; Electrochemical analysis; Electrodes; Electrolytes; Flux density; high energy density; Ionic liquids; Nonaqueous electrolytes; porous carbon; Specific surface; Studies; Supercapacitors; Surface area; X-ray diffraction
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2017.01.095

We demonstrate a simple, facile and one step activation process for the bio-derived activated carbon from corncob bio-waste. It showed a high specific capacitance of 390Fg−1 and the fabricated symmetric supercapacitor device could power red LED for more than 4min upon charging for 10s at 0.5Ag−1 current density. [Display omitted] •Corncob derived activated carbon was demonstrated for supercapacitors applications in aqueous and ionic liquids.•A high specific capacitance of 390Fg−1 was observed in aqueous electrolytes.•The fabricated device in ionic liquid could power a red LED for 4min. Corncob carbon prepared by means of (KOH) chemical activation method at 600°C for 1h 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 ∼800m2g−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 390Fg−1 at 0.5Ag−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 174Wkg−1. The supercapacitor device fabricated using the ionic liquid could power a red LED for more than 4min after upon 10s charging. The above investigation clearly indicates that the corncob derived carbon materials are promising for applications in supercapacitor.