New insights into ordering and dynamics in organic ionic plastic crystal electrolytes

Solid state phases of organic salts, whose chemistry is closely related to that of ionic liquids, often show interesting phase behavior and dynamics resulting in solid-state conductors that have potential application in electrochemical devices such as solid state batteries. The mechanism of conduction in these solid-state plastic crystal phases is still not entirely understood. We have recently shown using molecular dynamics (MD) simulations that the introduction of defects, such as vacancies, leads to heterogeneous dynamics in the OIPC arising from amorphous and mobile domains in these materials. Advanced magnetic resonance imaging (MRI) analysis indicates that these domains can exhibit distinct orientations, leading to anisotropic ionic conductivity with enhanced values in a particular direction. This paper will review this new understanding, drawing links between the molecular and macroscopic-level information provided by these two techniques.