Electric Double-Layer Capacitors Based on Multiwalled Carbon Nanotubes: Can Nanostructuring of the Nanotubes Enhance Performance?

Abstract

Supercapacitors prepared from chemically modified and vacuum filtered buckypapers were studied. The aim was to evaluate how its pore structure impacts on the specific capacitance, energy and power density in different electrolytes. The specific capacitance varies in a linear fashion with the specific surface area for nanotubes modified by the means of catalytic, low-temperature partial catalytic oxidation using cobalt oxide nanoparticles decorating the nanotubes. In contrast, electrodes composed of nanotubes preactivated in CO 2 demonstrated only a minor increase in their specific capacitance, despite the observed significant increase in specific surface area. The radically improved surface area was a result of emergence and deposition of soot on the nanotubes during the activation process, as revealed by transmission electron microscopy. Among six different types of electrode materials, the CoO x decorated materials proved to have the highest specific capacitance (~25 F/g in aqueous KOH and ~15 F/g in triethylsulfonium bis(trifluoromethylsulfonyl)imide ionic liquid). Thus, highly structured carbon nanotubes giving rise to energy and power storage densities comparable with commercial and other multiwalled carbon nanotube based electric double-layer capacitor devices were obtained.

Unbiased biocatalytic solar-to-chemical conversion by FeOOH/BiVO4/perovskite tandem structure

“…The electron transfer from the CNT cathode to M was further investigated via cyclic voltammetric analysis with varying scan rates (Supplementary Figure 6A ). In the cyclic voltammograms, capacitive charging current was observed due to the double-layer formation at the surface of the CNT film in the aqueous electrolyte 24 , 25 . We deconvoluted the faradaic current by the redox reaction from the measured cyclic voltammogram (Supplementary Figure 6B ) to evaluate the electrochemical interaction between the CNT film and M .…”

Aligned carbon nanotube/zinc oxide nanowire hybrids as high performance electrodes for supercapacitor applications

“…53 The ESR value obtained for this particular device was found to be approximately ~4.2 Ω, (Figure 4(b)) which is comparable with 7, 4, 3, and 5.5 Ω as measured on pure MWCNT, RuO2/ MWCNT, TiO2/MWCNT, and SnO2/MWCNT nanocomposite electrodes, respectively. 48,49 At a low frequency, the impedance shows a straight line with an acute angle between 45 _ and 90 _ , which is a real impedance. This line represents the diffusion of ions in the MWCNT/ZnO NW electrode.…”

MXene/Carbon Nanotube Hybrids: Synthesis, Structures, Properties, and Applications

“…CNTs (as the typical carbon-based nanomaterials) have been applied to fabricate EDLCs while MXenes are considered as intercalation-type pseudocapacitive materials. [168] In order to mitigate the severe stacking of 2D materials and improve the ion accessibility, CNTs are used as spacers and incorporated into MXene nanosheets, and MXene/CNT hybrids with volumetric capacitance of around 700 F cm À 3 have been reported. [169] In addition, various strategies have been developed to enhance the capacitance of MXene/CNT-based electrodes, such as the application of organic electrolyte, metal oxides, and conductive polymers in the system, and these electrodes are promising candidates in fabricating both symmetric and asymmetric supercapacitors (as shown in Table 6).…”