Ionic transport in glassy electrolytes

Laboratoire d lonique et d Electrochimie du Bolide, UR A D1213 CNRS, Institut National Polytechnique de Grenoble 

Whatever the mobile ion is, all the vitreous electrolytes have a transport number of unity and below their vitreous transition temperature, ionic conductivity follows an Arrhenius law  

Almost all vitreous electrolytes have similar values for the preexponential term. (that is the extrapolated value for conductivity when temperature tends to infinity) of between 10 and 10 S cm . They differ among themselves mainly because of different values for the activation energy ., which is very sensitive to the concentration and the nature of the mobile cation being usually between 0.2 and 1 eV. Consequently, near room temperature a large variation in the conductivity is observed, between 10 Scm and 10 Scm . This general behaviour is illustrated in Fig. 4.1(a). 

For most oxide based glasses, the best conductivities are only some 10 S cm at ambient temperature and 10 S cm at 300°C and as a result their use is largely confined to high temperatures and the electrolytes must be prepared as thin films (Levine, 1983 Jourdaine et al.. 

In the last 20 years, new sulphide, sulphate, molybdate, halide, etc., based compositions have been obtained in the glassy state (Ingram, 1987). They have much higher ionic conductivity than most oxide glasses at ambient temperature, e.g. from 10 to 10 S cm in the case of some lithium or silver conducting glasses (Fig. 4.1(h)). 

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