Conductive carbon powder

A classic case is an EC of a faradic type in which an electrode is comprised of Ni(OH)2, MnOOH, etc. active materials. Since in these chemistries the conductivity depends on electrode state-of-charge charge level, they require presence of additional stable conductive skeletons in their structure. Noteworthy mentioning that besides traditional forms of carbon or other conductors that may form such a skeleton, the latest progressive investigations demonstrate the possibility of application of different nanostructured forms of carbon, such as single-wall and multi-wall carbon nanotubes [4, 5], Yet, for the industrial application, highly conductive carbon powders, fibers and metal powders dominate at present. 

Antistatic additives are capable of modifying properties of plastics in such a way that they become antistatic, conductive, and/or improve electromagnetic interference shielding (EMI). Carbon fibers, conductive carbon powders, and other electrically conductive materials are used for this purpose. 

The HgO is usually mixed with a conductive carbon powder, like graphite, to improve the electrical conductivity of the cathode. Mercuric oxide forms Hg as it is... 

One or more conductive carbon powders, like acetylene black and graphite, and a binder such as PTFE are added to the Mn02 to yield the cathode mix. 

Positive electrode materials are generally mixed with a conductive carbon powder and a polymer binder. Commonly used binders are polyvinylidene fluoride (PVDF) and a PVDF copolymer with hexafluorpropylene (PVDF-HFP). The positive electrode mix is coated as a slurry onto a thin aluminum foil current collector while the carbon negative electrode material, often using the same binders, is coated onto a thin copper foil current collector. 

The cathode pellet contains Ag20 powder and 1-5% of a conductive carbon powder like graphite, to reduce internal resistance and provide good contact to aU of the active silver oxide particles, mixed with a PTFE binder to maintain the mechanical integrity of the pellet. 

The change of the nature of the catalytic material can indeed allow the modification of these characteristics, hut also the control of the structure and of the morphology of platinum - in terms of crystalUte size, exposed surface domains, internal strains, etc. For these reasons, and also in order to decrease the amount of the noble metal, platinum is used for electrocatalysis as nanoparticles dispersed on a high surface area electronic conductive carbon powder (carbon nanograins, carbon nanotubes, carbon nanofibers, etc.), as shown in Fig. 9.7. 

The percolation threshold, cpc, is the fiUer loading level at which the polymer first becomes conductive, which is generally considered to be a value of about 10 S/cm. Comprehensive experimental and theoretical treatments describe and predict the shape of the percolation curve and the basic behaviors of composites as a function of both conductive filler and the host polymer characteristics (36-38). A very important concept is that the porous nature of the conductive carbon powders significantly affect its volume filling behavior. The typical inclusive stractural measurement for conductive carbon powder porosity is dibutyl phthalate absorption (DBF) according to ASTM 2314. The higher the DBF, the greater the volume of internal pores, which vary in size and shape. The crystalhnity of the polymer also reduces the percolation threshold, because conductive carbons do not reside in the crystalhtes but instead concentrate in the amorphous phase. Eq. (2) describes the percolation curve (39). 

Table 14 compares the theoretical and experimental results for percolation of two conductive carbon powders in a FF of two different melt flows, 4 and 44 g/10 min, when prepared by two melt-processing techniques, compression... 

Reduced Wear Electrical Conductivity Glass fibers Carbon fibers Lubricating additives Carbon fibers Carbon powders Ductility, cost Tensile strength, ductility, cost Ductility, cost Tensile strength, ductility, cost... 

The catalyst layer is the most expensive part of this fuel cell. It is made from a mixture of platinum, carbon powder, and PEM powder, bonded to a conductive carbon fiber cloth. We obtained ours from E-Tek Inc. The cost for an order of their ELAT catalyst cloth sheet includes a setup charge. So get together with others for a larger order if you want to keep costs down. We paid 360 for a piece of ELAT 15.2 centimeters by 15.2 centimeters [6 inches by 6 inches] including the 150 setup charge. This piece provides enough for about twelve disks. Each fuel cell requires two disks of ELAT and one larger disk of PEM to make the sandwich, so you can make six cells from this size... 

Microstructures of CLs vary depending on applicable solvenf, particle sizes of primary carbon powders, ionomer cluster size, temperafure, wetting properties of carbon materials, and composition of the CL ink. These factors determine the complex interactions between Pt/carbon particles, ionomer molecules, and solvent molecules, which control the catalyst layer formation process. The choice of a dispersion medium determines whefher fhe ionomer is to be found in solubilized, colloidal, or precipitated forms. This influences fhe microsfrucfure and fhe pore size disfribution of the CL. i It is vital to understand the conditions under which the ionomer is able to penetrate into primary pores inside agglomerates. Another challenge is to characterize the structure of the ionomer phase in the secondary void spaces between agglomerates and obtain the effective proton conductivity of the layer. 

Pt/Ru electrocatalysts are currently used in DMFC stacks of a few watts to a few kilowatts. The atomic ratio between Pt and Ru, the particle si2 e and the metal loading of carbon-supported anodes play a key role in their electrocatalytic behavior. Commercial electrocatalysts (e.g. from E-Tek) consist of 1 1 Pt/Ru catalysts dispersed on an electron-conducting substrate, for example carbon powder such as Vulcan XC72 (specific surface area of 200-250 m g ). However, fundamental studies carried out in our laboratory [13] showed that a 4 1 Pt/Ru ratio gives higher current and power densities (Figure 1.6). 

Kay A (1996) Low cost photovoltaic modules based on dye sensitized nanocrystalline titanium dioxide and carbon powder. Solar Energy Mater Solar Cells 44 99-117 Wang X, Zhi L, Muellen K (2008) Transparent, conductive graphene electrodes for dye-sensitized solar cells. Nano Lett 8 323-327... 

A typical configuration of a double-layer supercapacitor involves two metallic collectors which hold in place the carbon powder electrodes, which in turn are separated by an electrolyte, in most of the cases formed by liquid solutions (Fig. 9.28.) A layer of porous, non-conductive material acts as a separator. 

Nickel hydrate, usually 5-10% cobalt added, serves as the active material and is mixed with a conductive carbon, e g., graphite. The active mass is mixed with an inert organic binder such as polyethylene or poly(tetrafluoroethyleiie) (TFE). The resultant mass is rolled into sheets on a compounding mill or pressed into electrodes as a dry powder on a nickel grid. 

To ensure a sufficient electronic and thermal conductivity of the positive electrode during the charge and discharge process, conductive additives are required in the positive, transition metal oxide-based electrode.3133 Compared to metal powders as potential conductivity enhancer, carbon materials combine high electronic and thermal conductivity with low weight, low costs, relatively high chemical inertness, and nontoxicity. Conductive carbons optimize the electrical resistivity of the positive electrode mass but are not involved in the electrochemical redox process which delivers the... 

The types of graphitic carbon powders which primarily are applied as conductive additive belong to the family of highly crystalline graphite materials. These graphite materials show real densities of 2.24-2.27 g cm-3 (values based on the xylene density according to DIN 12 797 and DIN 51 901-X) and average interlayer distances of c/2 = 0.3354-0.3360 nm.55... 

When applied as conductive additive in the positive electrode, graphite and carbon black show complementary properties which are summarized in Table 7.3. The decision which carbon type should be selected depends on the cell requirements and the type of active electrode materials used in the electrodes. The TEM pictures in Figure 7.7 compare the morphology of a typical conductive carbon black and a graphite powder and illustrate the dimensional differences of the primary particles of a factor of about 10. 

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