Design of superionic polymers for energy storage applications

Replacing traditional liquid electrolytes by polymers will significantly improve electrical energy storage technologies. Despite the significant advantages for applications in electrochemical devices, the use of solid polymer electrolytes has been impeded by their poor ionic conductivity. By analyzing the relationship between ionic conductivity and segmental relaxation, we demonstrate that polyether-based solid electrolytes have intrinsic limitations for ionic transport at ambient and low temperatures, due to strongly coupled segmental and ion dynamics. On the other hand, the ionic conductivity in rigid polymer can be strongly decoupled from segmental relaxation, in terms of both temperature dependence and relative transport rate, thus providing a significant advantage over traditional polyether-based electrolytes. Our analysis emphasizes that decoupling of ionic transport from segmental dynamics is the key for macromolecular design of superionic polymers.