Unraveling Mechanisms of Strongly Correlated Dynamics in Ionic Systems

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In this project funded by the Chemical Structure Dynamics and Mechanisms-A (CSDM-A) program of the Chemistry Division, Professors Alexei Sokolov and Stephen Paddison of the University of Tennessee will combine experimental and computational studies to develop a fundamental understanding of the mechanisms controlling correlations in ion dynamics in concentrated ionic systems. These correlations strongly influence ionic conductivity, and their mechanism remains a mystery. Using a broad array of experimental techniques combined with high fidelity simulations, a detailed molecular-level description of the distinct ion-ion correlations that may enhance or suppress conductivity in liquid and solid electrolytes is being developed. The results of these studies will likely impact the fundamentals of a wide range of ion conducting materials and will be important for rational design of novel electrolytes for various electrical energy storage technologies. The students and postdoc engaged in this project will gain valuable experience in sophisticated experimental and computational research. The Sokolov research group is also engaged in various outreach activities targeted at K-12 audiences.This project focuses on synergistic experimental and computational studies of ion and charge transport in ionic liquids, polymerized ionic liquids and organic ionic plastic crystals. Experiments involve Broadband Dielectric Spectroscopy, neutron scattering, and NMR will be combined with ab initio and classical atomistic molecular dynamics (MD) simulations and electronic structure calculations. The proposed study will likely provide a comprehensive knowledge of the role of ion size, disparity in the ion and counter-ion mobility, and electrostatic interactions on ionic correlations. The results will also reveal specific structure or compositions that may tune ion-ion correlations from negative (suppressing conductivity) to positive (enhancing conductivity). This study will help to develop design criteria for novel electrolytes that may be utilized in solid state batteries, flow batteries and other electrochemical applications, and provide good opportunities for the training of graduate students and postdoctoral researchers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.