Ultrafast Ionic Hopping, Electron, and Phonon Correlations in Solid-State Electrolytes
Abstract
An ionic species moving through a solid-state lattice may induce many-body correlations with charge carriers, phonons, and other ions – just as an electron moving through a lattice. After the discovery of superionic conductors, such as RbAg4I5, lattice-gas type models predicted that high ionic conductivity could only exist if the ion and phonons were correlated on vibrational time scales4–6. As the ionic conductivity of synthesized materials increased, later work posited that ionelectron cloud and ion-ion correlations must also be present7–10. A model based on the geometric hindrance of the lattice channel, ignoring many-body correlations, fails to describe many superionic conductors7,10–12. Current measurements of battery dynamics are usually limited to microsecond and longer times with impedance techniques. Nuclear magnetic resonance studies can access faster dynamics with site specificity through linewidth changes13. Neutron scattering can measure pair-correlations which are interpreted to short time scale dynamics14,15. However, for these techniques, the hopping time is extrapolated from Arrhenius type plots, leading to a reported nine order of magnitude spread in the fit hopping frequency16. Not being able to temporally resolve the picosecond ionic hopping dynamics inhibits the development of these complex but increasingly commercially and defense relevant materials. For example, the need to control many-body correlations are exacerbated in many next generation technologies like divalent batteries17,18. A few measurements at XFEL’s have emerged which provide insight into picosecond lattice dynamics but not a complete atomistic picture of ultrafast ion hopping19,20.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 29, 2024
- Source ID
- FA95502310197
Entities
People
- Scott K Cushing
Organizations
- Air Force Office of Scientific Research
- California Institute of Technology
- United States Air Force