Electrical Conductivity Of Carbon Research Articles

Self-interlocked MXene/polyvinyl alcohol aerogel to enhance flame retardancy, dynamic mechanical properties and electrical conductivity of carbon fibre/epoxy composites

Carbon fiber (CF) reinforced polymer composites (CFRPs) are often damaged by impact, fire and lightning strikes, which limit their wide applications. In this work, the flame retardancy, impact resistance and electrical conductivity of CF reinforced epoxy (EP) composites have been simultaneously improved through the self-interlocked 3D skeleton of Ti3C2Tx/polyvinyl alcohol (PVA) aerogel (TPA). The CF/EP and TPA/CF/EP composites have been characterized using Cone tests, split Hopkinson bar tests, and current tests. It is shown that TPA can suppress the release of heat, smoke particles and toxic gases in virtue of heat trapping, catalytic and barrier mechanisms at high temperature. The stitching effect of TPA can effectively limit the delamination failure and promote the absorption of fracture energy. Compared with the CF/EP composites, the Young's modulus of TPA/CF/EP composites has been increased by 22.7% in the range from 1967 s−1–2003 s−1. The crack initiation time of the TPA/CF/EP composites was delayed by about 50%. Moreover, the 3D skeleton of TPA facilitates the formation of current channels within the TPA/CF/EP composites, which enables the overall improvement of the electrical conductivity of the TPA/CF/EP composites in the longitudinal, transverse, and through-thickness directions. Among them, the electrical conductivity increases up to 61% in the through-thickness direction has been attained.

An interconnected and scalable hollow Si-C nanospheres/graphite composite for high-performance lithium-ion batteries

Silicon (Si) anode is the most promising alternative for next generation lithium-ion batteries (LIBs) owing to large theoretical capacity, low working voltage and abundant natural resources. However, tremendous volume change of Si during the (de)lithiation processes causes repetitive formation of solid electrolyte interphase (SEI) layers, loss of electrical contact and electrodes pulverization, limiting its commercial application. Herein, we fabricate an interconnected hollow Si-C nanospheres/graphite composite via a facile and scalable approach. Notably, hollow Si-C nanospheres and graphite are homogeneously combined by using the surfactants as surface modifiers of graphite and introducing carbon dioxide (CO2) into magnesiothermic reduction reaction, resulting in the enhanced compatibility between hollow Si-C nanospheres and graphite, and the well-established electrical conductive network. The resultant Si-C nanospheres/graphite composite anode with carbon content of 59 wt% delivers a large reversible specific capacity of 662 mAh g−1 and a high capacity retention of 65.7% at 0.5 A g−1 after 200 cycles. Such excellent rate performance and superior cycling performance are attributed to high electrical conductivity and buffering effect of graphite, superior compatibility between hollow Si-C spheres and graphite, uniform distribution of both Si-C nanospheres with a unique hollow architecture and graphite flakes inside the composites and well-established interconnected electrical conductive carbon networks, which can effectively alleviate Si volume expansion and maintain good electrical contact during cycling. This strategy provides insights into designing Si-based anodes for practical LIBs.

Increasing electrical conductivity of PMMA-MWCNT composites by gas phase iodination

A highly electrical conductive multi-walled carbon nanotubes based polymer composite is fabricated by iodine doping. Selective localization of carbon nanotubes in polymethyl methacrylate was obtained by intensive dry mixing of polymer and nanotubes powders followed by hot pressing. The electrical conductivity of the materials was significantly increased (10–100%) when the composites were treated with iodine by the gas phase. The electrical conductivity of the materials was significantly increased because of MWCNTs addition from the value not higher than about 10−15 to about 10−2 S/cm. The addition of iodine leads to an additional increase in electrical conductivity by 10–100%, depending on the content of MWCNTs. It is interesting to note that a more effective increase in electrical conductivity is observed at low MWCNTs concentrations. An interesting result of the work is the presentation of the fact that iodine is uniformly absorbed in the bulk of the composite filled with nanotubes; in the case of an unfilled polymer, iodine is deposited only on the sample surface. The percolation nature of the conductivity of the investigated composites was found and the percolation threshold was calculated. It was shown that the percolation threshold does not significantly change after iodination. Thus, in this work, we have shown the possibility of simple technology for producing composites with a spatial localized distribution of carbon nanotubes, providing high conductivity (2.86 × 10−2 S/cm) and a low percolation threshold (about 0.37% vol.) at the MWCNTs content of 1.55% vol.

UV-ozone contributions towards facile self-assembly and high performance of silicon-carbon fiber materials as lithium-ion battery anodes

Si-carbon composites have been considered as next generation lithium-ion battery anodes, with a view to sufficiently exerting the respective superiorities of high specific capacity of Si as well as excellent mechanical flexibility and electrical conductivity of carbon. However, direct blending of carbon with Si cannot obtain a synergy composite, resulting in inferior cycle properties during charge–discharge due to huge volume changes and deficient electron-conducting channels from the unavoidably aggregated Si. Herein, the composition of carbon fibers (CNFs) with Si nanoparticles (SiNPs) has been performed through UV-ozone surface modification followed by electrostatic self-assembly. It is found that solvent-free UV-ozone exposure of CNFs for 20 min successfully introduces carboxylic groups, as conventional acid treatment for 12 h. Besides UV-ozone surface modification provides an efficient and scalable route, the distribution and functionalization of CNFs can be also modified to effectively combine with amino-functionalized SiNPs. As a result, such Si-CNF composites containing 70.0 wt% SiNPs are able to exhibit excellent cycle performance with high coulombic efficiency of 74.8% at the 1st cycle and high specific discharge capacity of 1063 mAh g−1 at the 400th cycle.

Graphene oxide thin film structural dielectric capacitors for aviation static electricity harvesting and storage

In this paper, we demonstrate the feasibility of using carbon fibre reinforced polymer (CFRP) laminates for the dual functions on aircraft as high load-bearing structural materials as well as for the harvesting and storage of static electricity during flight which can be used to power navigation lights and other electrical systems. CFRP laminate was fabricated into a structural dielectric capacitor (SDC) composite by sandwiching graphene oxide (GO) film between two electrically-conductive carbon fabric layers. To meet the high requirements of aviation applications, the mechanical properties of the GO-based SDC composite were increased using a polymer cross-linking agent in the GO film. This work opens a new concept and possibility of converting the safety threatening static charges into useful electrical energy, which not only reduces the safety hazard, but also improves the energy efficiency of aircraft without compromising the mechanical performance.

Preparation of reduced graphite oxide loaded with cobalt(II) and nitrogen co-doped carbon polyhedrons from a metal-organic framework (type ZIF-67), and its application to electrochemical determination of metronidazole.

The integration of derivatives ofgranular metal-organic frameworks (MOFs) and an electricallyconductive carbon substrate is an effective way to circumvent the deficiency of powdered pristine MOFs or MOF-derived carbon in practical application. The authors describe the use of graphite oxide (GO) as a substrate for in-situ assembly with the zeolitic imidazole framework ZIF-67. The GO and ZIF-67 composites were converted,via pyrolysis, into reduced graphite oxideloaded withCo/N-co-doped carbon polyhedrons (ZIF-67C@rGO). By using various amounts of GO, a series of ZIF-67C@rGO-x with different fractions of GO were synthesized and utilized as electrode modifiers for the detection of the antibiotic metronidazole (MNZ). The results revealed that the ZIF-67C@rGO-0.06 display best sensing performance. This is likely to be due to its hierarchically open pores, abundant active sites and good electrical conductivity. The sensor, best operated near a working potential around -0.6V (vs. SCE), has a linear response in the 0.5 to 1000μM MNZ concentration range and a 0.05μM detection limit. The sensor was applied to theanalysis of pharmaceutical samples where it showed excellent selectivity, good repeatability and satisfying recoveries. Graphical abstract Schematic representation of preparation and application of ZIF-67C@rGO-x.

Electrical conductivity of carbon black/single‐wall carbon nanotube/low‐density polyethylene ternary composite foam

ABSTRACTIn order to obtain high electrical conductive low‐density polyethylene (LDPE) foam, carbon black (CB), single‐wall carbon nanotube (SWCNT), and LDPE (CB/SWCNT/LDPE) ternary composite foams were successfully fabricated by chemical compression molding method. The electrical conductivity, mechanical properties, microstructure, density, and crystallinity of the foam were studied in detail. It can be found that CB and SWCNT have synergistic effect. For the CB/SWCNT/LDPE composite foam which containing 19 wt % CB and 0.05 wt % SWCNT, its density is only 0.082 g cm−1 and the electrical conductivity can reach at 2.88 × 10−5 S cm−3, which is far more than 15 orders of magnitudes of pure polyethylene and 4 orders of magnitudes times higher than sample which CB content is 19 wt %. It is noteworthy that ultralow concentration of SWCNT could drastically improve the electrical conductivity and reduce the density of LDPE foams. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48382.

Amine-functionalized graphene and its high discharge capacity for non-aqueous lithium–oxygen batteries

Amine-functionalized graphene was synthesized via a one-step solvothermal method and used as a metal-free cathode for non-aqueous lithium–oxygen batteries. The material delivered an outstanding specific capacity of 19,789 mAh/g at a current density of 200 mA/g as well as better cycling stability than graphene without the amine functional group. This improvement was attributed to the electron-donating effect of the amine groups and appropriate mesopore volume, which can promote the penetration of oxygen, electrons, and lithium ions, as well as accommodate more discharge products, Li2O2 in Li–O2 batteries. Amine-functionalized graphene has an amine functional group on the carbon surface, which improves the electrical conductivity of carbon and provides electrochemical active sites for oxygen absorption reactions.

Powdered activated carbon enhanced Manganese(II) removal by chlorine oxidation

Chlorine is not effective in the oxidative removal of soluble manganese(II) ions at neutral pH. Powdered activated carbon (PAC) also has a very limited capacity for Mn(II) removal through adsorption in drinking water treatment practice. This study explored the combined use of PAC and chlorine for Mn(II) removal and found that PAC dramatically catalyzed Mn(II) oxidation by chlorine under diverse conditions. At a dose as low as 5.0 mg/L, two different commercial PACs increased Mn(II) oxidation rate by two orders of magnitude respectively and reduced Mn(II) concentration from 200 μg/L to < 10 μg/L in tens of minutes. First-order kinetics with respect to aqueous Mn(II) concentration were observed. Typically, homogeneous Mn(II) oxidation by chlorine depends strongly on alkaline pH. In the presence of PAC, however, the reaction was still rather fast at pH 6.0. Increasing PAC doses linearly increased Mn(II) oxidation rate, indicating that the reaction was highly PAC surface active sites dependent. The efficacy of PAC was further corroborated in removing Mn(II) from natural water. SEM-EDS and XPS demonstrated that a MnO2 coating was formed on PAC surface after reaction, which resulted from heterogeneous oxidation of Mn(II) on PAC surface rather than the precipitation of Mn oxides formed through homogeneous oxidation in solution. Adsorption of free Mn(II) ions onto PAC surface was proved to directly correlate with Mn(II) oxidation rate. Two kinds of electron transfer pathways from adsorbed Mn(II) species to chlorine, enhanced by surface-complexation and electrically-conductive carbon surface respectively, were hypothesized.

Electrical properties of FCVA deposited nano-crystalline graphitic carbon thin films with in situ treatment techniques

In this report, detailed studies of the nano-crystalline graphitic (NCG) carbon thin films deposited by filtered cathodic vacuum arc (FCVA) following its first discovery and first electrical characterization have been performed. The microstructure of carbon thin film can be modified by applying in situ treatment techniques (such as altering the thermal and carbon ion deposition energy). It was found that highly electrical conductive carbon thin films with graphitic planes can also be deposited at a low deposition temperature instead of the previously reported high deposition temperature with a 20% improvement in electrical characteristic. The detailed electrical characterization comparison between amorphous carbon and NCG has been conducted. To conclude, NCG carbon can be fabricated at deposition temperature above 400 °C and exhibits increasing through film Ohmic electrical conductivity with increasing deposition temperature. At low temperatures, NCG carbon can be produced by increasing the negative substrate bias above 300 V (impinging carbon ion energy). Higher negative substrate bias leads to thinner amorphous interface layer hence better electrical conductivity.

Mosquito’s Compound Eyes as Inspiration for Fabrication of Conductive Superhydrophobic Nanocarbon Materials from Waste Wheat Straw

Converting waste wheat straw to conductive superhydrophobic nanocarbon materials is inspired by mosquito’s compound eyes, and a one step pyrolysis process is used for controllable construction of micro/nanohierarchical structures. Their structures and hydrophobicity can be tuned efficiently by the annealing temperature. Scanning electron microscopy, elemental analysis, X-ray diffraction, laser Raman, Fourier transform infrared, and photoelectron spectroscopy analyses were used to reveal the structure of electrical conductive carbon materials (ECMs) and a possible mechanism of the nanostructures formation. These results indicate that there are big differences between the surface and the inner structure for the nanocarbon materials, and the releasing rates of a multicomponent gas at different annealing temperatures by further decomposition of waste wheat straw should be pivotal to the formation of nanostructures. There is also cause for superhydrophobicity and electroconductivity for the ECM-800. Considerin...

Organic Eutectic Electrolytes for Future Flow Batteries

In this issue of Chem, Yu and coworkers report phthalimide-based eutectic anolytes, which achieved a high concentration and enhanced redox reversibility. The organic-molecule-based eutectic electrolytes take advantages of both the superior tunability of the organic molecule and the high molar concentration of the redox-active molecules of the eutectic solvents. With combined computational and experimental analysis, this work demonstrates that forming eutectic electrolytes with self-containing redox-active organics is a promising strategy for the future development of high-energy-density redox-flow batteries.

Tip-welded ferric-cobalt sulfide hollow nanoneedles on highly conductive carbon fibers for advanced asymmetric supercapacitors

The ever-increasing concerns about global environmental problems and depletion of fossil resources have stimulated intensive research on low-cost and high-performance energy storage materials. Here, we introduce the two-step sulfidation of hierarchical ferric-cobalt sulfide hollow nanoneedles on electrical conductive carbon fiber paper (CFP) for high-performance supercapacitor electrodes. Under the growth regulation of macroporous CFP substrate, prepared free-standing composite paper with tip-welded ferric-cobalt sulfide hollow nanoneedles can offer substantial exposed electroactive sites for Faradaic redox reaction and effectively buffer the drastic volume change during long-term charge-discharge, and also provide fast charge transfer paths through the carbon skeleton for efficient energy storage. Due to these unique features, obtained composite paper electrode delivers a higher specific capacitance (2282 F g−1 at current density of 1 A g−1) than those of the previously reported MCo2S4 based electrodes. Asymmetric supercapacitor assembled using the composite paper as the binder-free positive electrode also shows a high energy density of 86.8 Wh kg−1 at a power density of 800 W kg−1, and an impressive 82.3% capacitance retention after 5000 cycles, demonstrating the great potential of this low-cost and free-standing electrodes towards high-performance energy storage.

Characterization of resistors created by fused filament fabrication using electrically-conductive filament

Desktop fused filament fabrication (FFF) printers (3D printers) are ubiquitous rapid prototyping (RP) and additive manufacturing (AM) devices used by small and large companies as well as by hobbyists. Their attractiveness stems from the inexpensive hardware, inexpensive plastic materials, affordable CAD environments, and short training times. This research explores design of resistors created by the FFF printing process using commercially available electrically-conductive carbon black and graphene-based filament. 3D printed resistors are designed, constructed, and characterized. A number of tests are performed resulting in a set of build recommendations. With this novel capability to directly create electrical components integrated into 3D printed physical objects designers can envision and 3D print new and/or improved devices with embedded electronics, which they could not do before.

Synthesis and properties of electrical conductive and antibacterial siloxane-modified carbon fiber–silver–acrylate nanocomposites

ABSTRACTFirst, silanized carbon fiber (SCF) was synthesized, then silanized carbon fiber–silver (SCF-S) was obtained. Finally, silanized carbon fiber–silver–acrylate (SCF-S-A) electrical conductive and antibacterial composites were prepared. The structures of CF, SCF, SCF-S, and SCF-S-A were characterized by X-ray photoelectron spectroscopy, FTIR, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV spectra. The electrical conductive and antibacterial properties of SCF-S-A nanocomposites were studied. The results showed that electrical conductive and antibacterial activity properties of SCF-S-A nanocomposites were improved. When the content of SCF-S was 50%, the conductivity of SCF-S-A nanocomposites was maximum. The SCF-S-A nanocomposites will have promising application in high-performance electrical conductive and antibacterial materials.

Preparation of conductive carbon films from polyacrylonitrile/graphene oxide composite films by thermal treatment

Electrically-conductive carbon films were prepared by the thermal treatment of polyacrylonitrile/graphene oxide (PAN/GO) composite films. PAN/GO composite films spin-coated on substrates were stabilized in air and then carbonized under inert atmosphere at 1000°C to form carbon films. It was found that the cyclization of PAN and the partial reduction of GO occurred simultaneously during stabilization. The incorporation of GO was found to help to lower the energy and temperature of cyclization by an additional ionic reaction mechanism and to form large and compact crystalline structures. The electrical conductivity increased to 5.92×102S/cm with an increasing GO content.

Polypropylene Based Piezo Ceramic Compounds for Micro Injection Molded Sensors

Polymer matrix compounds based on piezo ceramic and electrically conducting particles within a thermoplastic matrix show distinctive piezoelectric and dielectric effects which can used for sensor applications. The electrical and mechanical properties can be adjusted in a wide range by varying the ratio of active filling particles and the matrix materials. The sensor effect of the compound is generated by the ceramic particles. A large ratio of piezo ceramic powder facilitates a high sensitivity. The electrical permittivity of the otherwise insulating matrix polymer can be adjusted by the amount of conductive filler. An aligned permittivity leads to a stronger electrical field in the ceramic particles. In contrast, too many conductive particles create a conductive network in the compound which short-circuits the sensors. The piezo ceramic compounds can be processed via micro injection molding for application as ceramic sensors. This offers a wide range of new sensor design variants, notably three-dimensional and highly complex geometries. However, there are two main demands for a highly sensitive sensor, which are conflicting. On the one hand the filler content of piezo ceramic particles in combination with electrical conductive carbon nanotubes must be very high, on the other hand the wall thickness should be as thin as possible. For filling cavities with a high aspect-ratio in an injection molding process, low viscosity polymer melts are necessary. These process characteristics conflict with the increasing viscosity by filling the melt with the particles. The sensor measuring area has to be designed as thin walled as possible. In order to overcome this obstacle a dynamically tempered mold design is applied to avoid solidification of the melt, before the mold is completely filled. The mold can be tempered by Peltier elements. The fully electric tempering is cleaner, more precise and more reliable than conventional water or oil tempering.

Antioxidant sustained release from carbon nanotubes for preparation of highly aging resistant rubber

In this work, a novel strategy to avoid the blooming of antioxidants and improve the aging-resistance of styrene-butadiene rubber (SBR) was proposed by using carbon nanotubes (CNTs) loaded with antioxidant N-(1, 3-dimethyl) butyl-N′-phenyl-p-phenylenediamine (4020) as filler. The sustained release of antioxidant from carbon nanotubes extends its action time. The amount of antioxidant in the rubber composites allows for a concentration of 2.0wt.% without causing blooming by encapsulating antioxidant into carbon nanotubes. The aging resistance of SBR/CNTs composites was studied by comparing the mechanical properties before and after thermal-oxidative and ozone aging. A fifteen-day thermal-oxidative aging test at 100°C shows preservation of mechanical properties and a twenty-four-hour ozone aging test shows no cracks. Furthermore, due to the present of thermal and electrical conductive carbon nanotubes, the rubber composites emerge thermal conductivity of 0.303W/m·K and electrical conductivity of 4.74×107Ω·cm which can be extended for many potential applications, such as long service life tires and antistatic conveyer belts. This loading and sustained release approach can be extended to antimicrobial, antifouling, and other application.

Electrical conductivity of carbon nanotube/polypropylene composites prepared through microlayer extrusion technology

Abstract The morphological distribution of carbon nanotubes (CNTs) in polymer matrix has a crucial impact on the performance of CNT-filled polymer composites. A novel microlayer extrusion technology used in the dispersion and orientation of CNTs was proposed, and polypropylene (PP)/multiwalled CNT (MWCNT) composites with different numbers of layers were prepared with it. The MWCNT dispersion was investigated by scanning electron microscopy and Raman mapping method, and the MWCNT orientation was quantified by Raman spectroscopy. The influences of the dispersion and orientation of MWCNTs on the electrical conductivity and crystallization behavior of the composites were investigated. The results showed that the anisotropic conducting properties of the multilayered composites varied distinguishably with the increase of layer numbers and rotation speed. Furthermore, the degree of crystallinity of PP increased when the layer number increased from 1 to 729. All of these results suggest that with the increase of the layer numbers and the rotation speed, the dispersion and orientation of MWCNTs in PP matrix improve greatly. Overall, we provide an efficient and practical approach to control the dispersion and orientation of CNT in polymer matrix, which has a promising application prospect in the field of plastic processing.

Characterization and modeling of the effective electrical conductivity of a carbon nanotube/polymer composite containing chain-structured ferromagnetic particles

The effective electrical conductivity of multi-walled carbon nanotube/polydimethylsiloxane composites with chain-structured ferromagnetic particles has been investigated by experiments and micromechanics-based modeling. A multi-scale modeling approach is used to consider different size of fillers of multi-walled carbon nanotubes and particles as well as their distribution in the matrix. At nanoscale, for multi-walled carbon nanotube/polydimethylsiloxane composite, eight-chain model and influence of waviness of multi-walled carbon nanotube are considered to render an effective electrical conductivity. At microscale, ferromagnetic particles are aligned in the matrix made of the multi-walled carbon nanotube/polydimethylsiloxane composite, and an analytical model is established based on representative volume element. The influence of inter-particle distance is evaluated. The proposed analytic results agree well with the experimental results. The present model can be a useful tool for design and analysis of these composites for sensing applications considering their percolation threshold and overall electrical conductivity.