Impact of Structural Coherence and Disorder on the Ionic Transport and Lattice Dynamics in Li+-conducting Argyrodites

Among candidate solid electrolytes, lithium argyrodites stand out for their exceptional ionic conductivity and compositional flexibility. Recent studies have revealed strongly anharmonic, liquid-like ion and lattice dynamics in these materials, including the collapse of soft phonons driven by Li⁺ diffusion, which impacts both local vibrations and thermal transport.

Yet, the connection between local structure, phonon dynamics, and macroscopic heat transport remains unresolved. In this work, we employ post-synthesis processing to tune microstructural parameters—such as crystallite size, strain, and coherence length—in two model systems: Li5.5PS4.5Cl1.5 and Li6PS5Br,. We systematically examine how mechanical treatments influence structural coherence, ion and lattice dynamics, and thermal transport.