Facile preparation and electrochemical characterization of cobalt oxide/multi-walled carbon nanotube composites for supercapacitors

• Published in: Journal of power sources 2011-09, Vol.196 (18), p.7841-7846
• Main Authors: Lang, Junwei, Yan, Xingbin, Xue, Qunji
• Format: Article
• Language: English
• Subjects: Applied sciences; Capacitors; Capacitors. Resistors. Filters; Carbon nanotube; Cobalt oxide; Cobalt oxides; Composite; Current density; Electrical engineering. Electrical power engineering; Electrochemical impedance spectroscopy; Exact sciences and technology; Materials; Multi wall carbon nanotubes; Nanoparticles; Specific surface; Supercapacitor; Supercapacitors; Various equipment and components
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.04.010

► The composites were synthesized by a facile chemical co-precipitation method. ► The MWCNTs were well dispersed in the loosely packed Co 3O 4 nanoparticles. ► The electrochemical performances of pure Co 3O 4 were significantly improved. ► The Co 3O 4-5%MWCNT composite showed the largest specific capacitance of 418 F g −1. ► The Co 3O 4-5%MWCNT composite exhibited good cycling stability and lifetime. A series of cobalt oxide/multi-walled carbon nanotube (Co 3O 4/MWCNT) composites are successfully synthesized by a facile chemical co-precipitation method followed by a simple thermal treatment process. The morphology and structure of as-obtained composites are characterized by X-ray diffraction, scanning electron microscopy, and N 2-adsorption/desorption measurements, and the electrochemical properties are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). For all Co 3O 4/MWCNT composites, MWCNTs are well dispersed in the loosely packed Co 3O 4 nanoparticles. Among them, the Co 3O 4-5%MWCNT composite exhibits the highest specific surface area of 137 m 2 g −1 and a mesoporous structure with a narrow distribution of pore size from 2 to 10 nm. Because of the synergistic effects coming from Co 3O 4 nanoparticles and MWCNTs, the electrochemical performances of pure Co 3O 4 material are significantly improved after adding MWCNTs. The Co 3O 4-5%MWCNT composite shows the largest specific capacitance of 418 F g −1 at a current density of 0.625 A g −1 in 2 M KOH electrolyte. Furthermore, this composite exhibits good cycling stability and lifetime. Therefore, based on the above investigation, such Co 3O 4/MWCNT composite could be a potential candidate for supercapacitors.