Textile electrodes electrode surface area

Similar to the experiments carried out at palladium electrodes and described in Chapter3, the concentration of electrolyte (c), the electrode surface area (A) and the distance between the electrodes (d) will be studied as a function of type of textile structure. In this work, three structures will be studied knitted, woven and non-woven textile structures, all obtained from stainless-steel fibres. To complete the data of this work, palladium sheets will also be inserted in the study as a fourth set of electrodes. Therefore, for palladium electrodes, the work described in section 9.2 will actually be repeated here in order to have a direct comparison between results obtained with palladium electrodes and textile electrodes. Of course, correlation with the data obtained in section 9.2 will be verified. 

Logarithmic plot of the impedance at zero phase-angle shift as a function of electrode surface area obtained from the electrochemical cell with palladium and textile structure electrodes, c/=103mm, 7"=298.0Kand an electrolyte concentration of (1) 10, (2) 10 2, (3) 10 3 and (4) 10 4moll. ... 

In this section, the distance between the electrodes is studied for different electrolyte concentrations and distances between the electrodes at a constant electrode surface area of A = 180 mm2. The obtained impedances are plotted logarithmically against the distance between the electrodes (d) as shown in Fig. 9.14. Relationships obtained for the textile electrodes are identical to those for the palladium electrodes if the smallest distance between the electrodes is not taken into account. Additionally in this case, the roughness of the textile electrodes is responsible for this effect and can be neglected for distances longer than d=40mm - an effect that increases with decreasing distance between the electrodes. Of course, also in this case,... 

In recent years, many types of double-layer capacitors have been built with porous or extremely rough carbon electrodes. Activated carbon or materials produced by carbonization and partial activation of textile cloth can be used for these purposes. At carbon materials, the specific capacity is on the order of 10 J,F/cm of trae surface area in the region of ideal polarizability. Activated carbons have specific surface areas attaining thousands of mVg. The double-layer capacity can thus attain several tens of farads per gram of electrode material at the surfaces of such carbons. 

An important application field for stainless steel fibers is the textile sector, in which 0., i to 6% of these fibers are incorporated to endow carpets, protective clothing etc. with an antistatic finish. A further application is protection against electromagnetic pulses, interference and charging. Tungsten fibers with a diameter of 12 pm are used for boron or SiC deposition and as light bulb filaments. Furthermore, metal fibers are used in the filtration of polymer melts and corrosive liquids, as well as for electrodes with high surface areas. 

The current density of a single-wall carbon nanotube sheet electrode, with infused platinum nanoparticles as the cathode in a microbial fuel cell, was approximately an order of magnitude higher than that with an e-beam-evapo-rated platinum cathode. The enhancement of catalytic activity can be associated with the increase of the catalyst surface area in the active cathode layer [61]. In another study, MFCs with carbon nanotube mat cathodes produced a maximum power density of 329 mW m , more than twice of that obtained with carbon cloth cathodes (151 mW m ) [62]. A similar twofold improvement was obtained by electrochemically depositing Pt nanoparticles on a CNT textile cathode for aqueous cathode MFCs, with only 19.3% Pt loading of a commercial Pt-coated carbon cloth cathode [63]. 

Chain stitch embroidery is a modification of the standard embroidery technique. It is technically similar to crochet and is used for further embroidery techniques such as kettle and moss embroidery. Moss embroidery utilizes a single thread system where the needle punches through the base material and pulls the thread out from under the needle, plate side up. The rotary motion of the needle creates a loop on the upper side of the base material. Repeating this technique in a tight area produces a surface with a texture akin to moss (see Fig. 9.13). As this technique produces a high surface area on the front side of the fabric, it has applications in medical textiles including chain stitch embroidered textile electrodes. 

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