Ionic transport and structure in doped plastically crystalline solids

There is considerable interest in plastic crystalline electrolytes which have good room temperature ionic conductivities and potential technological applications as membranes for devices such as batteries. Conductivity and X-ray absorption spectroscopy measurements have been used to study succinonitrile (1,2-dicyanoethane) doped with copper(I) and (II) triflate (trifluoromethanesulfonate) and TFSI (bis(trifluoromethane)sulfonimide). The conductivities at room temperature are reasonably good, particularly for Cu(I)TFSI doped at 1 mol%, where the conductivity is � 1�10 -3 S cm -1, which is consistent with previous work on this system. The Cu K-edge EXAFS in 1 mol% doped copper salts show that in all cases, whether Cu(I) or Cu(II), the ion is predominantly in a well-defined and ordered local environment. A tentative model of the conduction process is described that will account for this local structural information; however, the process is clearly complex even in these apparently simple systems. © by Oldenbourg Wissenschaftsverlag, München.