| Home > Publications database > Impact of structural coherence and disorder on the ionic transport and lattice dynamics in $Li^+$ -conducting argyrodites |
| Journal Article | FZJ-2025-04368 |
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2025
RSC
London [u.a.]
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Please use a persistent id in citations: doi:10.1039/D5TA07185B doi:10.34734/FZJ-2025-04368
Abstract: Solid-state batteries offer improved safety and higher energy density compared to conventional lithium-ion systems. 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 the 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: $Li_{5.5}PS_{4.5}Cl_{1.5}$ and $Li_6PS_5Br$. We systematically examine how mechanical treatments influence structural coherence, ion and lattice dynamics, and thermal transport. To further probe the role of structural disorder, we investigate bromide substitution in $Li_6PS_5I$. Across all compounds, thermal transport above 100 K is dominated by diffusons. At lower temperatures, however, structural disorder is significantly more effective than reduced coherence length at suppressing phonon-gas-type transport, underscoring the crucial role of the local structure. Together with a detailed analysis of lithium-ion dynamics, these results provide new insights into how structural coherence and disorder govern both transport and vibrational properties in fast ionic conductors.
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