PMI/PCCM SEMINAR SERIES FALL 2024: Annalise Maughan, Colorado School of Mines

Hosted by Kelsey Hatzell
Date
Nov 6, 2024, 12:00 pm1:00 pm

Details

Event Description

Site Disorder Drives Cyanide Dynamics and Fast Ion Transport in Li6PS5CN

Abstract: Mastery over solid-state ion transport is paramount for broad diversity of applications and technologies, including batteries, fuel cells, neuromorphic computing, and beyond. Disorder – both static and dynamic – plays a crucial role in dictating ion diffusion in the solid state. Our work aims to harness and understand the impact disorder across time and length scales on ion transport processes in the solid state. The halide argyrodites Li6PS5X (X = halide, pseudohalide) are an exciting family of solid-state ion conductors in which to explore the impact of static and dynamic disorder. In this work, we have discovered the new solid electrolyte Li6PS5CN in which the halide site is occupied by the orientationally-disordered cyanide ion. Through a combination of solid-state nuclear magnetic resonance spectroscopy, electrochemical measurements, and machine-learning assisted molecular dynamics simulations, we find that the presence of disorder within the sulfide and cyanide anion substructures leads to vast differences in the timescales of lithium ion diffusion and cyanide rotational dynamics. Specifically, we find that the presence of this site disorder leads to fast, long-range Li+ diffusion, but sluggish or frozen cyanide dynamics. In contrast, ordered anion substructures enable fast cyanide rotational dynamics but inhibit longer-range lithium hopping dynamics. We rationalize the observed dynamics of cyanide in the context of dipolar coupling that dictates the energetic landscape for cyanide reorientations, and explore the potential for coupled dynamics between lithium and cyanide. Taken together, our work highlights the complex interplay between static site disorder, cyanide dynamic disorder, and lithium ion diffusion in Li6PS5CN.

 

Bio: Prof. Annalise Maughan is an Assistant Professor in the Department of Chemistry at Colorado School of Mines and holds a joint appointment with the National Renewable Energy Laboratory. She received her B.S. in Chemistry and a minor in Mathematics from Northern Arizona University and her Ph.D. in Chemistry from Colorado State University. She then joined NREL as a Director’s Postdoctoral Fellow prior to joining the faculty at Colorado School of Mines. Her research program is focused on solid-state materials for renewable energy, with an emphasis on understanding the fundamental principles that connect chemistry, local and long-range structure, and dynamics to functional properties such as charge transport and light absorption/emission. 

 

All seminars are held on Wednesdays from 12:00 -1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.