Electrochemical characterization of supercapacitors based on carbons derived from coffee shells

• Published in: Materials chemistry and physics Vol. 115; no. 1; pp. 33 - 39
• Main Authors: Jisha, M.R., Hwang, Yun Ju, Shin, Jae Sun, Nahm, Kee Suk, Prem Kumar, T., Karthikeyan, K., Dhanikaivelu, N., Kalpana, D., Renganathan, N.G., Stephan, A. Manuel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2009
• Subjects: Carbon; Chemical activations; Coffee shells; Porogen; Supercapacitors; Supercapacitors; Porogen; Chemical activations; Carbon; Coffee shells
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2008.11.010

Carbons derived by pyrolysis of coffee shells treated with ZnCl 2 were used as electrode materials in symmetric electrochemical supercapacitors. Scanning electron microscopy showed that the carbon from the porogen-free shells show a flake-like structure, while those from the ZnCl 2-treated coffee shells have a loose, disjointed structure with no definite shape. X-ray diffraction studies indicated the presence of small domains of coherent and parallel stacking of the graphene sheets. The average surface area of the carbon was 842 m 2 g −1, with an average micropore area of 400 m 2 g −1. Cyclic voltammetric studies suggested a specific capacitance of about 150 F g −1. Self-discharge studies on the devices showed a large retention time.