title: Carbon Nanotube-Based Supercapacitors with Excellent ac Line Filtering and Rate Capability via Improved Interfacial Impedance.
abstract: We report the fabrication of high-performance, self-standing composite sp(2)-carbon supercapacitor electrodes using single-walled carbon nanotubes (CNTs) as conductive binder. The 3-D mesoporous mesh architecture of CNT-based composite electrodes grants unimpaired ionic transport throughout relatively thick films and allows superior performance compared to graphene-based devices at an ac line frequency of 120 Hz. Metrics of 601 μF/cm(2) with a -81° phase angle and a rate capability (RC) time constant of 199 μs are obtained for thin carbon films. The free-standing carbon films were obtained from a chlorosulfonic acid dispersion and interfaced to stainless steel current collectors with various surface treatments. CNT electrodes were able to cycle at 200 V/s and beyond, still showing a characteristic parallelepipedic cyclic votammetry shape at 1 kV/s. Current densities are measured in excess of 6400 A/g, and the electrodes retain more than 98% capacity after 1 million cycles. These promising results are attributed to a reduction of series resistance in the film through the CNT conductive network and especially to the surface treatment of the stainless steel current collector.
authors.affiliation: Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Yverick
authors.initials: Y
authors.lastname: Rangom
authors.affiliation: Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Xiaowu Shirley
authors.initials: XS
authors.lastname: Tang
authors.affiliation: Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Linda F
authors.initials: LF
authors.lastname: Nazar
keywords: EDLC; ac line filtering; carbon nanotubes; electric double layer capacitor; electrochemical capacitor; high current density; supercapacitor; ultrahigh sweep rate