Ketjen black is basically a conductive agent and conductive agents are usually used to make sure that the electrode possesses good charge and discharge performance. So ketjen black is responsible for carrying out charges from one end to another. This works in various forms but its major contribution is in the form of a superconductor. A lot of experiments and researches were conducted in this regard and it came through that ketjen black is best used as a superconductor therefore its applications are quite vast in this regard.
Good discharge and charge performance of the electrode are ensured by using a conductive agent. When the pole piece is being produced, a conductive material is usually added in a particular amount, and a micro-current is collected between the current collector and the active material for reducing the microcurrent.
The rate of the movement of electrons is accelerated by the electrode’s contact resistance, and the contact resistance also increases lithium ions’ migration rate effectively at the same time, in the electrode material, thus enhancing the electrode’s charge and discharge efficiency. The resistance of interaction can be decreased and the conductivity of the electrodes can be improved by using the conductive agent carbon black.
Carbon Black Conductive Agent
The small size of the particle characterizes the conductive carbon black, specifically good electrical conductivity, and large specific surface area. Conductive carbon black can work in the battery as liquid retention and liquid absorption.
Ketjen black (Carbon ECP600JG, Carbon ECP, Ketjenblack EC600JD, Ketjenblack EC300J), carbon nanotubes (CNTs), carbon fiber (VGCF), 350 G, and acetylene black are the carbon black conductive agents.
Acetylene Black (Polyacetylene): If we decompose and purify the by-product gas during pyrolysis of naphtha (crude gasoline) or calcium carbide method, carbon black is attained by acetylene’s continuous pyrolysis and that acetylene should have a purity of 99% or more.
Ketjen Black: They have remarkable electrical conductivity, high purity, and are branched. They are highly efficient superconducting carbon black for lithium batteries.
Graphite conductive agent: SFG-15, SFG-6, KS-15, KS-6, etc.
CNTs: If one needs to create an electrical percolation network, the more effective method is incorporating carbon nanotubes as a conductive additive at a lower weight loading as compared to that of the conventional carbons, for instance, graphite and carbon black. In the industry, the highest electrical conductivity is offered by the Ketjenblack superconductive carbon black at the lowest concentration.
In comparison with the conventional carbon blacks, desired characteristics can be obtained by using substantially lower amounts of Ketjenblack EC-600JD, and Ketjenblack EC-300J because of their remarkable and rare morphology. There is little to no influence on the final product’s mechanical and processing characteristics as a result.
Applicable to all types
Ketjenblack is utilized in a vast number of applications which includes protective packaging for conductive paint, fuel cells, batteries, high voltage cables, conductive flooring, fuel tanks and hoses, safety shoes, and electronics. They can also be implemented in all kinds of elastomers and polymers.
High-performance Energy Storage Devices
The growing major concerns on fossil fuels depletion and the ubiquity of mobile devices have caused an urgent need for high-performance energy storage devices in recent years.
A huge amount of attention has been gained by the pseudocapacitors which are also known as the electrochemical capacitors because of the life span, high energy densities, and reasonably high power of the pseudocapacitors. Thus, they possess the potential to bridge the gap between the batteries and conventional capacitors. There have been extensive explorations on nickel-cobalt sulfide (NiCo2S4) as a type of pseudocapacitive material for its rich redox ability and high conductivity. Major progress has recently been obtained in improving that NiCo2S4-based electrode's specific capacitance.
There have been great efforts in controlling the architecture of NiCo2S4-based materials for balancing ionic and electron transporting. NiCo2S4-based materials have surely attained a huge amount of success regarding robust interfaces and a remarkable performance by using two extremely powerful approaches. One of those strategies is nanostructured material's direct growth on the substrates. For instance, NiCo2S4 nanotube arrays have been made by Xiao et al. on the carbon fiber paper and he also attained a 2.86 F cm-2 of high areal capacitance at 4 mA cm-2.
Production of the Nanosheet Arrays
Alshareef and his co-workers have recently made NiCo2S4 nanosheet arrays electrode with 1418 F g-1 of specific capacitance at 5 A g-1 through an electrodeposition method. However improved power density is showed by the as-attained additive-free electrodes because of low resistance, comparatively, low mass loadings may restrict their applications in the real life. Generally, long reaction time, high pressure, and high temperature are required by the hydrothermal method. Thus, searching for an environmental-friendly and facile method is very important as it can ensure high conductivity of the as-obtained electrodes and high mass of nanostructured NiCo2S4 loading on substrates.
Assembling Scrupulous Designs
The other way is using slurry-pasting to assemble the scrupulous designed NiCo2S4 -based nano-architectures on the substrates. High specific capacitance can be attained by the slurry casting method at the price of bulk agglomeration and additives’ extra weight. Although the benefits of the nanostructured materials can be eradicated by the lacking of spatial precision. The main problem with the production of electrodes is its stepwise construction of the optimal physical space with a huge mass loading. Ketjen Black/NiCo2S4 nanocomposite electrodes are produced by a two-step method which was presented as a proof-of-concept, with controllable mass loadings.
3D Interconnected Precursors
First, a facile modified solution-based method was used to directly grow the 3D interconnected flower-like Ni-Co precursors on the nickel foam. Robust interfaces can be provided by the substrate which was nearly covered with the attained Ni-Co precursors. Then, as poor electron and ion transporting always results because of the high mass loading, that's why the co-precipitation method synthesized the Ni-Co precursor/KB composite and conductive Ketjen Black (KB) has been added to NiCl2 /CoCl2 solution. The assembling of NiCo2S4/KB composite was successful on the nickel foams through an anion exchange reaction (AER), and a dip-dry process.
High Mass Loadings
Increased dipping numbers can achieve the electrode's high mass loadings. The high areal specific capacitance of 10.10 F cm-2 is shown by the unique electrode (Ni1K0.25) as a result at 10 mA cm-2, along with remarkable cycling stability (at 10 mA cm-2, 92.1% capacitance retention 6000 cycles), and good rate capacitance (38.41% capacitance retention at 40 mA cm-2), making it a promising and suitable electrode for the supercapacitors.
Production of NiCo2S4 /KB Nanocomposites and Their Characterization
In fields of supercapacitors, electrocatalysis, and lithium-ion batteries, KB is a less expensive conductive material because of KB's high conductivity and large specific surface area of almost 1270 m2 g -1. Although, the hybrid process in our work is significantly hindered by its hydrophobic characteristics. Thus, carboxylic moiety (-COOH) was introduced to KB for performing the surface modification treatment. KB and m-KB’s FR-IR spectrum guarantees the process of surface modification. The stretching vibrations of the C=O and -OH can be the reason for the new bands at 1729 cm-1 and 3424 cm-1 from mKB’s FT-IR spectrum, respectively, indicating the presence of the carboxylic moiety (-COOH) in m-KB, as it wasn’t present in the original KB. Thus, KB’s surface modification treatment can significantly help in the facilitation of the hybrid m-KB to Ni-Co precursors.
The coprecipitation process gave us Ni-Co precursor/KB composite after we added m-KB to the NiCl2 /CoCl2 solution. There is a possibility of an easy conversion of Ni-Co precursor/KB composites to the corresponding NiCo2S4 /KB composites by AER. The production of NiCo2S4/KB composite can be confirmed by NiCo2S4 /KB nanocomposite’s (in red) XRD patterns and corresponding NiCo2S4 (in blue) XRD patterns. 55.2°, 50.4°, 38.5°, 31.5°, and 26.8° are the peaks that are located at 2θ values and those peaks correspond to the diffraction planes of the cubic phase NiCo2S4 (JCPDF 43-1477).
The previous reports showed that the only characteristic peak marked with “*” can be well indexed to KB. According to the analysis, our proposed synthesis method was used to obtain a relatively high purity NiCo2S4 /KB nanocomposite. The composition of the NiCo2S4/KB nanocomposite sample was fully understood by carrying out the X-ray photoelectron spectroscopy (XPS) measurement. C, S, Co, and Ni element is present and it is showed in the survey spectrum. Two spin-orbit doublets were used to fit the Ni 2p spectrum, and they are properties of two shake-up satellites Ni3+ and Ni2+.
Two spin-orbit doublets are shown simultaneously by the Co 2p spectrum, and at 783.6 eV, they possess a low energy band (Co 2p3/2), and at 798.5 eV, they possess a high energy band (Co 2p1/2), respectively. Co3+ and Co2+ presence is confirmed by the spin-orbit splitting values of Co 2p3/2 and Co 2p1/2 which are more than 15 eV.
C, S2-, Ni3+, Ni2+, Co3+, and Co2+ makes up the NiCo2S4 /KB nanocomposite sample according to the XPS analysis mentioned above and it is consistent with that analysis. 3-dimensional interconnected flower-like NiCo2S4 nanosheets grow on the nickel foams directly as the first step through a subsequent anion exchange reaction (AER) and a facile modified solution-based method. Nickel foam's surface treatment process can be completely confirmed by NiCo2S4 nanosheets’ SEM images on the nickel foams. The skeleton of nickel foams uniformly covers the NiCo2S4 nanosheets. One can observe a 3-dimensional interconnected flower-like NiCo2S4 nanosheets on the magnification of the SEM image. However, robust contact is provided by the above step between the substrate and active materials which can significantly aid in the following step that is the achievement of comparatively low mass loadings.
Thus, nickel foam's mass loadings were enhanced by using the second step. The NiCo2S4/KB nanocomposites that have different mole fractions assembled successfully on the above nickel foams in the second step. According to observations, the AER method and coprecipitation synthesized pure NiCo2S4’s (Ni1K0) little quantity and it was loaded on the surface treated nickel foams and there was a merely dense growth of the 3-dimensional interconnected flower-like NiCo2S4 nanosheets. Although, on the substrate, NiCo2S4/KB composites were covered in a large quantity. The stepwise self-assembled nanosheets turned more compact and the pores of the 3-dimensional interconnected flower-like NiCo2S4 nanosheets were filled, resulting in the mass loading’s increase.
There was the implementation of the TEM images for further detailed analysis of the microstructure of the as-obtained NiCo2S4 /KB nanocomposite samples. Shortened pathways are provided by NiCo2S4 /KB nanocomposite's special structure. It also aids in effective electrolyte penetration, which consequently results in enhanced cycling stability and capacitance.
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N2 Sorption Measurement
The pore-size distribution of the NiCo2S4/KB nanocomposite samples and surface area of Brunauer-Emmett-Teller (BET) was evaluated by conducting the N2 sorption measurement. It’s the orientation to m-KB that significantly improved the surface areas of NiCo2S4 /KB nanocomposite i.e. 104.37 m²/g) as compared to the pristine NiCo2S4 (35.20 m²/g). Pore-size distribution analysis can ensure the pore size range of 4-5 nm of the NiCo2S4 /KB nanocomposite sample.
Control of Mass Loading on Nickel Foam via a Dip–dry Process
As reported in our old works, a dip-dry process can control NiCo2S4 /KB nanocomposite mass loadings on nickel foam well. The NiCo2S4 /KB nanocomposites filled the nickel foam's free pore volume with the increased dipping number and they covered the nickel foams skeleton gradually. In each dip-dry process, the as-prepared electrode's mass loading uniformly increases, which shows its high controllability. It is revealed by the low mass volatility in the process that there can easily be a repetition of the experimental results, and it is very significant for the scale-up.
Electrochemical Performance of the as-prepared Electrodes
There was direct usage of the NiCo2S4 /KB nanocomposites that were loaded on nickel foam in a three-electrode system as the working electrode. Galvanostatic charge/discharge measurements (GCD) and cyclic voltammetry (CV) were used to test the electrochemical performance of NiCo2S4 /KB nanocomposites. As compared to the ideal rectangular shapes, their shapes are clearly different, which shows the pseudocapacitive properties of the NiCo2S4 /KB nanocomposites.
Lessening in the redox reaction’s reversibility is indicated by the shifting of the redox peaks to more positive and negative potential as there was an increase in the scan rates.
The OH- diffusion in the electrodes causes it. During the low scan rates, the NiCo2S4 active material can completely react with the OH- ions. Furthermore, the integrated CV areas for the NiCo2S4 /KB electrodes (Ni1K0.125, Ni1K0.25, Ni1K0.5) are comparatively larger than the single NiCo2S4 electrode (Ni1K0) which ensures that NiCo2S4's electrochemical performance is significantly enhanced by the conductive KB. According to the observations, larger integrated CV areas are shown by the Ni1K0.25 electrode as compared to the Ni1K0.125 and Ni1K0.5 electrodes. Ni1K0.25 electrode is thus more appropriate and suitable for the supercapacitors.
b I av = (5) is the equation that has been applied for understanding the charge storage process further and for analyzing the CV spectra. In that equation, the variable parameters are b and a, the scan rate is presented by v (mV s-1), and the peak current is presented by I (A). The charge storage process can distinguish between the diffusion-controlled process (b=0.5) and the surface-controlled process (b=1) by using the ‘b’ parameter. The b-values for the single NiCo2S4 electrode (Ni1K0) revealed that the charge storage process is surface-controlled mainly and ranges from 0.6 to 0.5 at 5-40 mV s-1 of scan rate. Although, with their scan rate ranging from 10-60 mV s-1, the b values for NiCo2S4 /KB electrodes (Ni1K0.125, Ni1K0.25, and Ni1K0.5) are not above 0.5. Diffusion dominates the NiCo2S4/KB electrodes' charge-storage process. The above-mentioned analysis shows that in short, the electron transporting of the as-prepared electrodes can be significantly facilitated by the conductive KB.
The capacitance performances of the already attained electrodes were evaluated by performing galvanostatic charge/discharge measurements. The existence of the redox reactions is indicated by the two distinct plateaus in the charge/discharge curve and how it's consistent with the above-mentioned CV results. Also, at low current densities, the galvanostatic discharge/charge curves are almost symmetrical, exhibiting the already-made electrodes’ remarkably high electrochemical reversibility.
The following factors can be responsible for the remarkable electrochemical performance of the NiCo2S4 /KB nanocomposites. First, good electrical contact is provided by the NiCo2S4 /KB nanocomposites between the substrated and the active materials. Those composites are grown directly on nickel foam. Then, KB gives us a more conductive path to transport electrons when it serves as a fridge. Then NiCo2S4 /KB nanocomposites' microstructures result in an easier penetration of the electrolyte into the electrode's inner region. At last, the redox reactions at or near the electrode's surface are highly favored by the improved surface area of the NiCo2S4 /KB nanocomposites by providing more of the electroactive sites.
High-performance supercapacitors need the NiCo2S4 /KB nanocomposites to be successfully produced as a binder-free electrode on the surface-treated nickel foams for high-performance supercapacitors. In comparison with the pure NiCo2S4 electrode (NiK0), majorly improved electrochemical performance is showed by the as-prepared NiCo2S4 /KB nanocomposite electrodes (Ni1K0.125, Ni1K0.25, Ni1K0.5) with controllable mass loadings. According to the demonstrations of the electrochemical measurements, the Ni1K0.25 electrode has a remarkable cycling stability (at 10 mA cm-2, 92.1% capacitance retention 6000 cycles), good rate capacitance (at 40 mA cm-2, 38.41% capacitance retention), and a competitive areal specific capacitance (at 10 mA cm-2, 10.10 F cm-2). In conclusion, a promising electrode for applications in practical life is the high-performance NiCo2S4/KB nanocomposite electrode. Furthermore, it also promotes a facile interface design approach to control the electrode's mass loading which is beneficial for the production of high-performance energy storage devices.
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Applications of Ketjenblack
One of the extremely pure carbon black known as Ketjenblack EC-600JD is really appropriate and suitable for electroconductive and antistatic applications. In comparison with the conventional electroconductive blacks, only one-sixth of Ketjenblack EC600-JD amount is required for achieving the same conductivity and that is because of its very high surface area of almost 1400 m2/g (BET) and remarkable morphology. Ketjenblack EC600-JD enables easier processing for the compounds that are sensitive toward the addition of filler, therefore lessening loss in the rheological and mechanical characteristics. The resulting compound’s conductivity can significantly increase when ketjenblack EC-600 JD thoroughly disperses with the polymer. One can use Ketjenblack EC-600JD in all kinds of elastomers, thermoplastic, thermoset, and polymers.
One can make a remarkable conductive material with extremely less amounts of Ketjenblack EC-600JD because of its remarkable and unique structure and morphology. A particular conductivity should be obtained by the loading so the type of polymer significantly determines the loading that is required. The special Ketjenblack EC Technical Bulletin gives us more of the available detailed information. Low ash content is possessed by Ketjenblack EC-600JD, which along with the very low loading level, results in it being a remarkable product in cable shielding for Semicon applications. During extrusion, an extremely smooth surface is provided by the low grit content.
Coatings and Primers
Primers and conductive coatings can be produced by using Ketjenblack EC-600JD. Optimal electroconductive performance can be obtained at extremely low loading levels, and it also lessens the loss in rheological and mechanical characteristics than the loss in Ketjenblack EC-300J. The same conductivity can be obtained by using Ketjenblack EC-300J but double the amount. Battery packaging for cell phones, automotive parts, carpet backing, flooring, tubing, IC parts, and many more are some of the other applications.
Ketjen Black is used in various forms and means but the best it can be used is in the form of a semiconductor. Depending upon the characteristics and properties that it is capable of possessing, the creditability of the product increases and enhances its authenticity.
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