Density of carbon nanotubes
Density of single-walled carbon nanotubes
Single-wall carbon nanotubes (SWCNTs) with diameters in the nanometer range are commonly referred to as carbon nanotubes. Iijima and Ichihashi and Bethune et al. independently discovered them in carbon arc chambers close to those used to make fullerenes in 1993. Carbon nanotubes with a single wall are an allotrope of carbon that sits halfway between fullerene cages and flat graphene.
Single-wall carbon nanotubes can be idealized as cutouts from a two-dimensional hexagonal lattice of carbon atoms rolled up along one of the hexagonal lattice’s Bravais lattice vectors to form a hollow cylinder, but they are not made this way. Periodic boundary conditions are applied along the length of the roll up vector in this construction, resulting in a helical lattice of seamlessly bonded carbon atoms on the cylinder surface. [three]
Carbon nanotubes are also known as multi-wall carbon nanotubes (MWCNTs), which are made up of nested single-wall carbon nanotubes that are weakly bound together in a tree ring-like structure by van der Waals interactions. These tubes resemble Oberlin, Endo, and Koyama’s long straight and parallel carbon layers cylindrically arranged around a hollow tube, if not identical.  Double- and triple-wall carbon nanotubes are often referred to as multi-wall carbon nanotubes.
We define the preparation of a graphene and single-walled carbon nanotube (SWCNT) composite film for use as electrodes in high energy density supercapacitors using a blending technique. Using a more realistic two-electrode testing method, specific capacitances of 290.6 F g(-1) and 201.0 F g(-1) were obtained for a single electrode in aqueous and organic electrolytes, respectively. The energy density of the organic electrolyte was 62.8 Wh kg(-1) and the power density was 58.5 kW kg (-1). Compared to graphene electrodes, the addition of single-walled carbon nanotubes increased energy density by 23% and power density by 31%. In ionic liquid at room temperature, the graphene/CNT electrodes had an ultra-high energy density of 155.6 Wh kg(-1). In addition, after 1000 cycles in an ionic liquid, the basic capacitance increased by 29%, suggesting excellent cyclicity. In graphene/CNT supercapacitors, SWCNTs served as a conductive additive, spacer, and binder. This research indicates that our graphene/CNT supercapacitors could be as good as NiMH batteries in terms of efficiency, and that they could be used in hybrid and electric vehicles.
Carbon nanotubes structure
Due to their quick charge/discharge speeds, high energy densities, and long lifetimes, new-generation energy-storage devices, such as supercapacitors, have become a hot research topic. With its key characteristics of good electrical conductivity, a large active surface area, and excellent mechanical/chemical stability, graphene holds a lot of promise for supercapacitors to achieve battery-level energy density. However, the effects of using graphene as a substitute for industrial activated carbon on supercapacitor electrodes have been disappointing.
The energy density of supercapacitors can be greatly increased by fabricating three-dimensional (3D) graphene sponges with a continuous, conductive structure and added porosity. Attempts have been made to assemble graphene sponges in order to enhance graphene’s electrode efficiency. Unfortunately, toxic reducing agents, negligible effects from tailoring the sponge microstructure, and complicated manufacturing processes have hampered the production and subsequent applications of graphene sponges for electrodes.
Density of carbon nanotubes kg/m3
Electrical interconnects, micro-contact probes, and thermal interface materials all benefit from increasing the density of carbon nanotube (CNT) forest microstructures. Density can be calculated using weight and volume for CNT forests on centimeter-scale substrates. This method, however, is not appropriate for smaller samples, such as individual microstructures, and it also does not allow for the mapping of spatial density variations within the forest. We show that optical attenuation can be used to quantify the relative mass density of individual CNT microstructures, with spatial resolution equal to the size of the centered spot. The propagation of a directed laser beam through CNT microstructures was measured using a custom optical setup. To measure the attenuation coefficient, the transmittance was associated with the thickness of the CNT microstructures using the Beer–Lambert–Bouguer law. We show that the density of CNT microstructures grown by CVD is dependent on their size, and that run-to-run process variations have a major impact on the overall density of arrays of microstructures. We also use the technique to calculate the change in CNT microstructure density as a result of capillary densification. For CNTs in future microfabrication processes, this is a useful and accessible metrology technique that will allow direct correlation of density to important properties like stiffness and electrical conductivity.