Chemical Physics Seminar: An Outsider׳s View of Ion Conduction in Solids

Zoom: https://us02web.zoom.us/j/87075995730?pwd=RWNJSDMvN3RJaEpPeXRoZkFnZzExQT09

Abstract:

Solid-state ion conductors may revolutionize battery technology by replacing the flammable organic electrolyte and achieving superior energy density. From a fundamental standpoint, ion conduction in solids is a fascinating phenomenon because such materials demonstrate behaviors of multiple phases of matter at once: part crystal, part liquid, part disordered solid. The current conceptual understanding of ion conduction in solids is mainly based on a static host-lattice model. This means that existing mechanistic models have implicitly assumed that the only important ionic motion in the solid is that of the mobile ions and the fluctuations of the ions that comprise the host lattice can be neglected.

In my talk, I will present a different approach to understanding this fascinating phenomenon. Our working hypothesis is that the motion of the mobile ions is strongly coupled to the structural dynamics of the rest of the lattice. Coupling of this sort means, by definition, that the overall structural dynamics of ion conductors are strongly anharmonic. To investigate this idea, we used polarization and temperature-dependent Raman scattering to study the thermal fluctuations of several prominent ion conductors. Our results indicate that anharmonic host-lattice dynamics is a phenomenon shared amongst these ion conductors. Our work suggests that tuning lattice anharmonicity may prove to be a novel route to improved solid ion conductor design.