Séminaire PHENIX | Xiliang Lian "Unraveling the interplay between Sn2+ translational motion and..."
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Le 06 juin. 2024
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14:00 - 16:00
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Séminaire
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Sorbonne Université Campus Pierre et Marie Curie
UFR de Chimie, tour 32-42 salle 101
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Lingsam Tea
| Séminaire | Doctorant |
| Titre |
UNRAVELING THE INTERPLAY BETWEEN Sn2+ TRANSLATIONALMOTION AND LONE PAIRS ORIENTATIONAL DYNAMICS IN TETRAGONAL BaSnF4
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| Présenté par |
Xiliang Lian |
| Affectation |
Laboratoire PHENIX |
| Résumé | Fluoride ion batteries (FIBs) are a promising post-Li-ion battery technology, but identifying solid-state electrolytes with high room temperature fluoride ion mobility remains a significant hurdle. Indeed, the research in this field is hindered by a limited understanding of the fluoride ion conduction mechanism. In particular, BaSnF4 exhibits a high ionic conductivity of 1×10-4 S/cm at ambient temperature, rendering it a potential solid electrolyte for FIBs, but the underlying ionic conduction mechanism for BaSnF4 and the involvements of Sn2+ lone pairs (LPs) in this process remain obscure. In this talk, I will first present our work on training the machine learning potential (MLP) for BaSnF4. We demonstrate that a polarizable ion model fails to capture the subtle interactions in BaSnF4, while the MLP yields excellent agreements with results obtained from highly accurate density functional theory calculations. Furthermore, the MLP also exhibits significantly boosted computational efficiency compared with the reference ab initio molecular dynamics method. Using machine learning molecular dynamics, we investigated how the motion of the various species affects the diffusion energy landscape. We demonstrated that the Sn2+ ions play a fundamental role. Their translational motion leads to an ionic conduction channel with a larger radius, thereby increasing BaSnF4 ionic conductivity. It also alters the LPs orientational dynamics. Furthermore, we comprehensively examined the fluoride ion diffusion behavior in BaSnF4 and confirmed two-dimensional diffusion within the Ba-Sn layers, while on the other direction the F- ions rapidly cross the Sn-Sn layer, creating Frenkel defects in the structure. Our work elucidates the atomistic mechanism governing the fluoride ion conduction in fast ionic conductors and will contribute to the rational design of FIBs solid electrolytes. |
| Contact PHENIX | Lingsam Tea |