Current-collector surface

The high resistivity of Inconel 600 (11 OjtI 0 8 Dm) demanded the application of this material as a composite with a central aluminum core. The aluminum was totally enclosed in Inconel 600 so that the Inconel was only exposed to sulfur and polysulfides. In a test over more than three years, cells with a composite current collector of this kind suffered from a high capacity decline. Post-test analysis showed that Inconel sustained polysulfide attack with the formation of a duplex nickel and chromium sulfide layer on the current collector surface. 

In general, this low conductivity weakness is circumvented by coating a thin active carbon layer on an aluminum current collector which provides a much better conductivity by minimizing the charge path length in the carbon. The electrode performance is sensitive to the adhesion of the carbon layer in contact with the current collector surface [21], It is important to ensure a good quality of this contact over time, even in presence of a solvent at elevated temperature, in order to maintain a low series resistance of the device. 

The life-limiting increase of resistance and decrease of capacity of cycled cells is usually attributed to the deteriorating effects of corrosion of the positive current collector— the cell container in the case of sodium core cells or a rod in the case of sulfur core cells. Apart from consuming the active material, corrosion may lead to the deposition of poorly conductive layers at the current collector surface, thus interrupting the contact of the inert electrode fibers with the current collector. Corrosion products may also deposit and block both the solid electrolyte and the electrode surface. The thermodynamic instability of metals in polysulfide melts severely limits the choice of materials interfacing the sulfur electrode.A fully satisfactory solution has not yet been reported. 

Figure 18.14. This results in a reduction of mass-transfer at that end of the bed close to the bulk solution, which in turn dampens the local mass-transfer coefficient. As this process continues, there builds up a point across the profile of the reactor, where the flux is maximum. Toward the current collector, more and more of the product is produced and as a result, the flux values are lower. Toward the bulk, the mass transfer is sluggish and thus on either side of the point of maximum, the flux values are lower. This point of maximum reaction front moves toward the current collector surface with increase in the residence time (t) and toward the end of the residence...

Influence of current-collector surface on formation of PbS04 crystals at grid-PAM interface... 

Fig. 3.40. Models for current-collector surface profiles and PbS04 crystals formed on (a) smooth surface (b) rough surface.

Influence of Current-Collector Surface on Formation of PbSO4 Crystals at Crid/PAM Interface... 

Portet, C., P. L. Taberna, P. Simon, and C. Laberty-RoberL 2004. Modification of A1 current collector surface by sol—gel deposit for carbon—carbon supercapacitor applications. Electrochimica Acta 49 905—912. 

Portet, C. 2004. Modification of Al current collector surface by sol-gel deposit for carbon-carbon supercapacitor applications. Electrochimica Acta, 49,905-912. 

Metal end plates are normally used as the current collectors because they possess sound mechanical properties that maintain the stack s structural stability and provide a facile means of connecting external leads. However, the current collector surface musf be treafed to enhance the contact of the... 

After etching, a carbonaceous coating can be applied by chemical vapor deposition [6] or carbonaceous sol-gel deposit methods [7] deemed capable of further decreasing the internal resistances of ES cells as low as 0.4 fl.cm. Therefore, new and modified current collector surface treatment techniques can promise to further decrease internal cell resistance and improve the overall performance of modern ESs. 

A current example investigating the mechanism of this method was employed by Borguet and coworkers. Utilizing small concentrations of silver ions and an electrochemical scanning tunnelling microscope, they were able to visualize the electrodeposition of Ag utilizing a sodium dodecyl sulfate (SDS) surfactant. In this case, the SDS adsorbs in parallel lines on the Au(lll) current collector surface. The lines appear wavy due to the adsorption of silver ions. After the application of... 

These potentials are those at the electrode current collector surfaces. Considering this, a disadvantage to MET in comparison to DET becomes apparent. In DET, the overpotential at the anode would be relative to the redox potential of the enzyme active site. In MET, the overpotential is relative to the mediator redox potential. For an anode, we may write an equation similar to Equation 9.6 (Equation 9.17) ... 

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