Solid maximum conductivity

Making use of Eq. (25), the maximum conductivity of a solid electrolyte with monovalent mobile species is given by... 

The mechanical properties of X depend partly on the length of the oli-goethyleneoxy groups. The polymers are solid for x=l, highly viscous gums for x=3 and elastomers for x=7.2. The maximum conductivity of these complexes at 30 °C are reported in Table 16. Gel electrolytes have also been obtained by adding propylene carbonate (PC) (10-50 wt%) to these polynorbornene de-... 

A concern for alkaline as well as solid polymer electrolysers should be the sensitivity of the electrolysers to contaminants in the feed water. The minimum required water quality of an industrial solid polymer electrolyzer is ASTM type II water [48], which contains at maximum 5 pg L 1 of sodium and chlorine, and 3 pg L 1 Si02 [52], It should have a maximum conductivity of 0.25 pS cm 1. Clean drinking water meeting Dutch standards contains around 60 mg L 1 of... 

Typical conductivity values of several polymers are shown in Fig. 1.1. The conductivity of polymers is compared with the conductivity of other solids in Fig. 1.2. It is seen that the maximum conductivity is quite high and close to that of good metals. 

With Ceo, as well as the larger analogs, atoms can be introduced into the internal cavities to form main-group versions of transition-metal clusters containing interstitial atoms. Entities such as main-group atoms like N or a rare gas, molecules tike H2, rare-earth metals and others can be encapsulated. As with external metals, the maximum conductivity occurs for internal metals which are able to transfer three electrons to the radial tiu band of solid C6o-... 

Selection of an appropriate solute is important for the formulation of an effective electrolyte. Maximum conductivity, for example, seems to be associated with a size homogeneity between the substituting species and the majority cation in the cubic structure, as well as its concentration in solid solution. Figure 3 presents the effects on the ionic conductivity of stabilised zirconia at a fixed temperature, on variation of the cationic substituting species. It is evident that the optimised yttrium solid solution has a conductivity of about 0.015 S cm at 800°C, so that only a very thin electrolyte membrane can provide a technically acceptable current density at that temperature. The well-established Westinghouse SOFC system therefore operates closer to 1000°C to take advantage of the rapid increase of electrolyte conductivity with temperature (7) (see also Fig. 7). This dependance, particularly steep for YSZ, is presented for several solid ionic conducting materials in Fig. 4. 

Fig. 2.6. Relation between the maximum temperature and the solid heat conductivity.

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