Performance of Electric Double-Layer Capacitor With Vertically Aligned MWCNT Sheet Electrodes Prepared by Transfer Methodology

A variety of vertically aligned multiwalled carbon nanotube (MWCNT) electrodes, which maintain their original morphology prepared by a chemical vapor deposition technique, has been successfully fabricated by a transfer methodology from a seedbed substrate to a current collector. No ohmic potential drop on a galvanostatic discharge was observed for an electric double-layer capacitor (EDLC) containing electrodes with not only a MWCNT length of 10 mu m but also a length of 200 mu m. Cyclic voltammograms for electrodes with MWCNT lengths of both 10 and 200 mu m showed no distorted current response, even at an extremely high scan rate of 50 V s(-1). These results demonstrate that the present EDLC with the MWCNT electrodes can provide an outstanding rate capability irrespective of the MWCNT length when prepared by our transfer methodology. To find suitable MWCNT electrodes for high-performance EDLCs, we investigated several relationships among the specific capacitances of aligned MWCNT electrodes and their major properties, i.e., their gravimetric and volumetric capacitances, length, diameter, and number density. (c) 2008 The Electrochemical Society. [DOI: 10.1149/1.2988743] All rights reserved.