Replacing traditional liquid electrolytes by polymers will significantly improve electrical energy storage technologies. Despite significant advantages for applications in electrochemical devices, the use of solid polymer electrolytes is strongly limited by their poor ionic conductivity. In this talk, several important design principles for polymer electrolytes will be discussed. In particular, we will focus on the fundamental relationship between ionic transport and segmental relaxation in polymers. The classical theory predicts that the ionic transport is controlled by the segmental motion of the polymer matrix. As a result, the low mobility of polymer segments is often regarded as the limiting factor for development of polymers with sufficiently high ionic conductivity. Using a modified Walden plot analysis, we show that the ionic conductivity in many rigid polymers can be strongly decoupled from their structural dynamics, in terms of both temperature dependence and relative transport rate.   On the other hand, polyether-based solid electrolytes have intrinsic limitations for ionic transport at ambient and low temperatures, due to strongly coupled segmental and ion dynamics. Our analysis emphasizes that decoupling of ionic transport from segmental dynamics is the key for successful design of �superionic� polymers.

Relationship between ionic transport and segmental relaxation in polymer electrolytes

248th National Meeting (2014)

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