Considering the Role of Ion Transport in Diffuson-Dominated Thermal Conductivity

Tim Bernges, Riley Hanus, Bjoern Wankmiller, Kazuki Imasato, Siqi Lin, Michael Ghidiu, Marius Gerlitz, Martin Peterlechner, Samuel Graham, Geoffroy Hautier, Yanzhong Pei, Michael Ryan Hansen, Gerhard Wilde, G. Jeffrey Snyder, Janine George, Matthias T. Agne, Wolfgang G. Zeier*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Next-generation thermal management requires the development of low lattice thermal conductivity materials, as observed in ionic conductors. For example, thermoelectric efficiency is increased when thermal conductivity is decreased. Detrimentally, high ionic conductivity leads to thermoelectric device degradation. Battery safety and design also require an understanding of thermal transport in ionic conductors. Ion mobility, structural complexity, and anharmonicity have been used to explain the thermal transport properties of ionic conductors. However, thermal and ionic transport are rarely discussed in direct comparison. Herein, the ionic conductivity of Ag+ argyrodites is found to change by orders of magnitude without altering the thermal conductivity. Thermal conductivity measurements and two-channel lattice dynamics modeling reveal that the majority of Ag+ vibrations have a non-propagating diffuson-like character, similar to amorphous materials. It is found that high ionic mobility is not a requirement for diffuson-mediated transport. Instead, the same bonding and structural traits that can lead to fast ionic conduction also lead to diffuson-mediated transport. Bridging the fields of solid-state ionics and thermal transport, it is proposed that a vibrational perspective can lead to new design strategies for functional ionic conducting materials. As a first step, the authors relate the so-called Meyer–Neldel behavior in ionic conductors to phonon occupations.

Original languageEnglish (US)
Article number2200717
JournalAdvanced Energy Materials
Volume12
Issue number22
DOIs
StatePublished - Jun 9 2022

Keywords

  • Meyer–Neldel
  • argyrodites
  • diffusons
  • ion conduction
  • phonon occupations
  • thermal transport

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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