Capacitive performance of onion peel derived carbon

Carbonaceous material has been derived from a domestic biomass waste viz., onion peel and assessed its suitability as electrodes in electrochemical double layer capacitors (EDLC). Onion Peel Carbon (OPC) has been obtained from pyrolysing onion peel under N2 atmosphere without any porogens or activating agents. Physical characterization of OPC by X-ray diffractometry, Infra Red spectroscopy, Scanning Electron Microscopy and elemental analysis followed by a critical assessment of its electrochemical behavior in H2SO4 electrolyte by cyclic voltammetry and galvanostatic charge-discharge cycling studies. Cyclic voltammetry estimates specific capacitance values as high as 206 F/g at a scan rate of 10 mV/sec. The specific capacitance decreases on increasing the scan rate. The results of the studies infer that OPC has immense application as electrochemical double layer capacitor electrode. The work thus contributes not only towards a waste utilization concept but also presents a new and valuable dimension to the usefulness of onion peel in energy storage systems like capacitors, hitherto unexplored.