Surface Modified Activated Carbons Prepared from Orange Peel Waste As Potential Electrodes for Li-Ion Capacitors

In this work, orange peel waste was used as the precursor for activated carbon-based electrodes for Li-Ion Capacitors. Initially, activated carbons were  prepared by chemical activation process using ZnCl₂.  The surface of the activated carbon was then modified  with the oxidative chemical agents (H₂SO₄,  HNO₃,  H₂O₂ and KOH solutions). The morphology, surface chemical composition, and surface area of the surface modified carbon materials were studied by scanning electron microscope, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement, respectively. Electrochemical characteristics of the as-prepared sample were investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements.  Experimental results showed that the surface modification had a very significant effect on the improvement of electrochemical characteristics of activated carbon as electrodes in supercapacitors. The good electrochemical performance of the activated carbon was attributed to well-developed micropores, high surface area, the presence of   oxygen functional groups, and larger pore volume.The results indicate that orange peel waste can potentially be applied as a raw material for the production of low cost activated carbon electrode materials for Li-Ion Capacitors.