Lead electronic conductivity

Electrons trapped at the vacancy can become partially or fully ionized, leading to weak n-ty e electronic conduction in an electric field. Again, the conductivity is low. 

One leading prototype of a high-temperature fuel cell is the solid oxide fuel cell, or SOFC. The basic principle of the SOFC, like the PEM, is to use an electrolyte layer with high ionic conductivity but very small electronic conductivity. Figure B shows a schematic illustration of a SOFC fuel cell using carbon monoxide as fuel. 

The electronic conductivity of lead dioxide is comparatively high thus there is no need for conducting additives. 

The plate support in lead-acid batteries is usually called the "grid". In most batteries the grid has to provide both mechanical support for the active material and electronic conductivity for the collected current. 

Another model assumes that gel zones are formed by hydrated lead dioxide (PbO(OH)2) and act as bridging elements between the crystallite particles. Electrons can move along the polymer chains of this gel and so cause electronic conductivity between the crystalline zones 137],... 

Accordingly, the ionic conductivity in an electrolyte with negligible electronic conduction (/jon jtolal) may be determined by Ohm s law, provided that unpolarizable electrodes are employed. To overcome this limitation, separate voltage probes in the shape of identical electronic leads connected to the electrolyte at positions separated by a distance L may be employed (four-probe technique [38]). Under these... 

D-TEM gave 3D images of nano-filler dispersion in NR, which clearly indicated aggregates and agglomerates of carbon black leading to a kind of network structure in NR vulcanizates. That is, filled rubbers may have double networks, one of rubber by covalent bonding and the other of nanofiller by physical interaction. The revealed 3D network structure was in conformity with many physical properties, e.g., percolation behavior of electron conductivity. 

Another convenient way to disperse platinum-based electrocatalysts is to use electron-conducting polymers, such as polyaniline (PAni) or polypyrrole (PPy), which play the role of a three-dimensional electrode.In such a way very dispersed electrocatalysts are obtained, with particle sizes on the order of a few nanometers, leading to a very high activity for the oxidation of methanol (Fig. 10). 

An imperative condition for materials being used as an electrolyte is the complete (or practically complete) absence of electronic conduction. Such conduction would amount to internal short-circuiting, leading to unproductive power consumption and/ or waste of electrode materials. 

Apart from individual sites, series of metal ion sites provide electron conduction paths, vital in energy transduction in all organisms and leading to proton transfer, and Mg2+ in chlorophyll is essential for light capture (see Section 4.17). 

As our quantum-chemical calculations show, similar transformation and delocalization of bonds takes place in the conductive forms of some other types of CPs (polyaniline, polypyrolle, etc.). Delocalization of chemical bonds after activation leads to appearance of an electronic conductivity in such types of conducting polymers and creates prerequisites for their application as electrode materials of electrochemical power sources. Such activation can be stimulated by intercalation of ions, applying the potential, and by use of some other low energetic factors. 

Taking as an example an ionic oxide MO, this material can be made into a metal-excess nonstoichiometric material by the loss of oxygen. As only neutral oxygen atoms are removed from the crystal, each anion removed will leave two electrons behind, which leads to electronic conductivity. The oxygen loss can be incorporated as oxygen vacancies to give a nonstoichiometric oxide with a formula MOi v, or the structure can assimilate the loss and compensate by the introduction of cation interstitials to give a formula M1+xO. 

The cathode of a battery or fuel cell must allow good ionic conductivity for the ions arriving from the electrolyte and allow for electron conduction to any interconnects between cells and to external leads. In addition these properties must persist under oxidizing conditions. An important strategy has been to employ layered structure solids in which rapid ionic motion occurs between the layers while electronic conductivity is mainly a function of the layers themselves. 

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