Solid Electrolytes and Mixed Ionic-Electronic Conductors: An Applications Overview

Solid electrolytes are an unusual group of materials which have high ionic conductivity with negligible electronic conductivity. Examples are now known involving high conductivity of most monovalent and some divalent ions, e.g. Ag+ in RbAg415, Na' in /?-alumina, Li' in H-doped Li,N, 02in 9Zr0, * 1 Y 203 (yttria-stabilised zirconia), Fin PbSnF4 and H + in H U 0 2 P 0 4 * 4 H 2 0 (hydrogen uranyl phosphate, HUP) (Fig. 1 ) . There is another group of materials, mixed ionicelectronic conductors, that have high conductivities of both ions and electrons. Solid electrolytes and mixed conductors have been surveyed recently in ref. 1 and more comprehensively in ref. 2. The purpose of this review is to summarise the current status of the applications of these materials (Table 1) and to