Polymer electrolytes—Some principles, cautions, and new practices

We give a short review of the basics of ionic dynamics in simple ionic liquids and their solutions (liquid fragility, conductivity-viscosity relations, limiting high conductivity, decoupling of conductivity from viscosity, conductivity maxima in solutions, and ionicity), and then summarize how these conceptual underpinnings must change when the ionic liquid becomes an ionic polymer or salt-in- polymer solution − the field of polymer electrolytes. We discuss the generation of rubbery plateaus, segmental relaxation and its control of thermodynamics, ionicity, and gelation), and revisit some of the key equations needed to provide quantitative accounts of the observed behavior. Finally we describe two alternative approaches to preparing flexible solid electrolytes, both higher-dimensional and one of them all-inorganic.