Moving towards high-power, high-frequency and low-resistance CNT supercapacitors by tuning the CNT length, axial deformation and contact resistance

Abstract

In this paper it is shown that the electrochemical behaviour of vertically aligned multi-walled carbon nanotube (VANT) supercapacitors is influenced by the VANTs' length (electrode thickness), by their axial compression and by their interface with the current collector. It is found that the VANTs, which can be interpreted as a dense array of nanochannels, have an active area available to ions that is strongly affected by the electrode's thickness and compressional state. Consequently, the tested thinner electrodes, compressed electrodes or a combination of the two were found to be characterized by a significant improvement in terms of power density (up to 1246%), knee frequency (58,822% working up to 10 kHz), equivalent series resistance (ESR, up to 67%) and capacitance (up to 21%) when compared with thicker and/or uncompressed electrodes. These values are significantly higher than those reported in the literature where long VANTs with no control on compression are typically used. It is also shown that the ESR can be reduced not only by using shorter and compressed VANTs that have a higher conductance or by improving the electrode/collector electrical contact by changing the contact morphology at the nanoscale through compression, but also by depositing a thin platinum layer on the VANT tips in contact with the current collector (73% ESR decrease).

Bendable solid-state supercapacitors with Au nanoparticle-embedded graphene hydrogel films

“…Compared with the GH SC (R ct  = 16 Ω and R int  = 35 Ω), the NP-GH SC has relatively lower values of R ct (3 Ω) and R int (21 Ω), owing to the embedding of the high conductivity Au NPs. In particular, the relatively lower R int of the NP-GH SC is due to the increase in the number of conducting paths by the addition of Au NPs; the additional conducting paths between an active electrode material and the current collector lower the internal resistance1920.…”

Development of High Performance Electrochemical Capacitor: A Systematic Review of Electrode Fabrication Technique Based on Different Carbon Materials

“…91 In same year, Zhang et al also prepared MWCNT electrodes by molding the CNT with a PTFE binder material and reported a C sp of 18.2 F g −1 . 92 Nowadays, CVD appears as a promising technique for production high quality CNTs at large scales that is achieved by pyrolytic decomposition of hydrocarbon gases at elevated temperatures in the range of 600-1,200 • C. 93 There are two major technique used to fabricated CNTs based EC electrodes using CVD process; transfer technique 94 and direct growth technique. 13 (a) CNT: Transfer technique.-Technically, transfer technique is easily defined as transfer of CNTs from non-conducting substrate such as silicon (Si) substrates to the conductive substrate by cut-paste or printing technique to prepare CNT electrode.…”

Pyrolytic cyanobacteria derived activated carbon as high performance electrode in symmetric supercapacitor

“…EDLC, stores energy by reversible adsorption of ions at the interface between electrolyte and active electrode materials. Currently, carbon black, single and multiwall carbon tubes and graphene are the predominant materials used in EDLC [2,3]. However, these materials have several drawbacks, such as low SSA (specific surface area) and high cost, which limit their potential applications.…”