Corner-Sharing PS$_4$-BS$_4$ Modes Facilitate Fast Ion Conduction in Lithium Thioborophosphate Iodide Glassy Solid Electrolytes

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Main Author: An, Yun
Format: Preprint
Published: 2025
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author An, Yun
author_facet An, Yun
contents Glassy solid electrolytes (GSEs), with their amorphous nature and the absence of grain boundaries, make them highly attractive for applications in all-solid-state lithium batteries (ASSLBs), a leading candidate for next-generation energy storage technologies. A recently developed lithium thioborophosphate iodide GSE, composed of 30Li$_2$S-25B$_2$S$_3$-45LiI-5P$_2$S$_5$ (LBPSI), has demonstrated excellent room-temperature ionic conductivity and low activation energy. Despite this exciting finding, the underlying mechanism behind this ultrafast ion transport remains ambiguous. Here, we accurately fine-tune the foundational MACE-MP-0 model and perform large-scale machine learning molecular dynamics simulations to investigate the structural and ion dynamics in LBPSI GSE. Our results reveal that B$_2$S$_3$ glass formers primarily form multi-bridged B$_x$S$_y$ long-chain networks that impede Li$^+$ conduction. In contrast, P$_2$S$_5$ gives rise to mono-tetrahedral PS$_4$$^{3-}$ and di-tetrahedral P$_2$S$_7$$^{4-}$ tetrahedra, which engage in distinctive corner-sharing modes with BS$_4$$^{5-}$ tetrahedra, effectively disrupting the B$_x$S$_y$ chains and enhancing Li$^+$ mobility. Furthermore, the polyhedral anion rotations of PS$_4$$^{3-}$ and BS$_4$$^{5-}$ in the corner-sharing PS$_4$-BS$_4$ motifs may further promote fast Li$^+$ conduction.
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id arxiv_https___arxiv_org_abs_2507_08215
institution arXiv
publishDate 2025
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spellingShingle Corner-Sharing PS$_4$-BS$_4$ Modes Facilitate Fast Ion Conduction in Lithium Thioborophosphate Iodide Glassy Solid Electrolytes
An, Yun
Materials Science
Disordered Systems and Neural Networks
Glassy solid electrolytes (GSEs), with their amorphous nature and the absence of grain boundaries, make them highly attractive for applications in all-solid-state lithium batteries (ASSLBs), a leading candidate for next-generation energy storage technologies. A recently developed lithium thioborophosphate iodide GSE, composed of 30Li$_2$S-25B$_2$S$_3$-45LiI-5P$_2$S$_5$ (LBPSI), has demonstrated excellent room-temperature ionic conductivity and low activation energy. Despite this exciting finding, the underlying mechanism behind this ultrafast ion transport remains ambiguous. Here, we accurately fine-tune the foundational MACE-MP-0 model and perform large-scale machine learning molecular dynamics simulations to investigate the structural and ion dynamics in LBPSI GSE. Our results reveal that B$_2$S$_3$ glass formers primarily form multi-bridged B$_x$S$_y$ long-chain networks that impede Li$^+$ conduction. In contrast, P$_2$S$_5$ gives rise to mono-tetrahedral PS$_4$$^{3-}$ and di-tetrahedral P$_2$S$_7$$^{4-}$ tetrahedra, which engage in distinctive corner-sharing modes with BS$_4$$^{5-}$ tetrahedra, effectively disrupting the B$_x$S$_y$ chains and enhancing Li$^+$ mobility. Furthermore, the polyhedral anion rotations of PS$_4$$^{3-}$ and BS$_4$$^{5-}$ in the corner-sharing PS$_4$-BS$_4$ motifs may further promote fast Li$^+$ conduction.
title Corner-Sharing PS$_4$-BS$_4$ Modes Facilitate Fast Ion Conduction in Lithium Thioborophosphate Iodide Glassy Solid Electrolytes
topic Materials Science
Disordered Systems and Neural Networks
url https://arxiv.org/abs/2507.08215