Complementary Roles of Iodide-Mediated Pathways and Anion Dynamics in Lithium-Ion Transport in Li3PS4-LiI Glasses
- 1Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho Inage-ku, Chiba, Japan, 263-8522
- 2Lithium Battery Material Department Advanced Materials Company Idemitsu Kosan Co., Ltd., 1280 Kami-izumi, Sodegaura, Chiba, Japan, 299-0293
- 3Faculty of Materials for Energy, Shimane University, 1060, Nishikawatsu-cho, Matsue, Shimane, Japan, 690-8504
Abstract
LiI addition enhances lithium-ion transport in sulfide glasses, yet the microscopic mechanisms linking halide incorporation to faster conduction remain unclear. Here, we investigate how LiI promotes Li+ migration in (100−x)Li3PS4–xLiI glasses by resolving changes in local structure, migration energetics, and anion dynamics. A machinelearning potential trained on newly generated ab initio molecular dynamics data and an existing sulfide-electrolyte dataset enables 10 ns simulations of approximately 5000atom glass models at 300 K over a LiI content range of 0–50 mol%. The potential is validated against density functional theory calculations, experimental densities, and X-ray total scattering profiles. Although the PS4 3–units remain intact and their time-averaged inter-unit correlations change little, Li+ diffusivity more than doubles across this composition range, accompanied by increased migration beyond local cage-like regions. To characterize the energetics of these pathways in a disordered environment, we introduce an analysis that combines Voronoi partitioning into P-and I–-centered domains with atomic potentialenergy fluctuations along Li+ trajectories. The resulting statistical local energy-barrier indicators allow comparisons between domain transitions without assigning absolute activation energies. This analysis reveals two complementary effects of LiI addition. Transitions involving I–-centered domains exhibit lower barrier indicators than direct transitions between P-centered domains, identifying favorable I–-mediated migration pathways. LiI addition also lowers the barrier indicators for direct P-to-P transitions, extending its influence beyond pathways that pass through I–-centered domains. Enhanced local translational and rotational dynamics of PS4 3–units accompany this broader reduction, suggesting that anion motion helps facilitate Li+ migration. These findings explain how LiI can enhance transport while largely preserving the average glass structure and highlight the combined roles of local migration pathways and anion dynamics in designing sulfide glass electrolytes.
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BibTeX
@misc{sakuma2026complementary,
title = {{Complementary Roles of Iodide-Mediated Pathways and Anion Dynamics in Lithium-Ion Transport in Li3PS4-LiI Glasses}},
author = {Minami Sakuma and Shoma Kawano and Kazuki Fukuda and Aoto Matsuo and Futoshi Utsuno and Koji Ohara and Takahiro Ohkubo},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010277/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010277/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Complementary Roles of Iodide-Mediated Pathways and Anion Dynamics in Lithium-Ion Transport in Li3PS4-LiI Glasses
AU - Minami Sakuma
AU - Shoma Kawano
AU - Kazuki Fukuda
AU - Aoto Matsuo
AU - Futoshi Utsuno
AU - Koji Ohara
AU - Takahiro Ohkubo
PY - 2026
DA - 2026/10/12
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010277/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010277/v1
AB - LiI addition enhances lithium-ion transport in sulfide glasses, yet the microscopic mechanisms linking halide incorporation to faster conduction remain unclear. Here, we investigate how LiI promotes Li+ migration in (100−x)Li3PS4–xLiI glasses by resolving changes in local structure, migration energetics, and anion dynamics. A machinelearning potential trained on newly generated ab initio molecular dynamics data and an existing sulfide-electrolyte dataset enables 10 ns simulations of approximately 5000atom glass models at 300 K over a LiI content range of 0–50 mol%. The potential is validated against density functional theory calculations, experimental densities, and X-ray total scattering profiles. Although the PS4 3–units remain intact and their time-averaged inter-unit correlations change little, Li+ diffusivity more than doubles across this composition range, accompanied by increased migration beyond local cage-like regions. To characterize the energetics of these pathways in a disordered environment, we introduce an analysis that combines Voronoi partitioning into P-and I–-centered domains with atomic potentialenergy fluctuations along Li+ trajectories. The resulting statistical local energy-barrier indicators allow comparisons between domain transitions without assigning absolute activation energies. This analysis reveals two complementary effects of LiI addition. Transitions involving I–-centered domains exhibit lower barrier indicators than direct transitions between P-centered domains, identifying favorable I–-mediated migration pathways. LiI addition also lowers the barrier indicators for direct P-to-P transitions, extending its influence beyond pathways that pass through I–-centered domains. Enhanced local translational and rotational dynamics of PS4 3–units accompany this broader reduction, suggesting that anion motion helps facilitate Li+ migration. These findings explain how LiI can enhance transport while largely preserving the average glass structure and highlight the combined roles of local migration pathways and anion dynamics in designing sulfide glass electrolytes.
ER -