High Li+-Transference Number in Loose Coordinated Poly(tetrahydrofuran): A Molecular Dynamics Study,Macromolecules

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High Li+-Transference Number in Loose Coordinated Poly(tetrahydrofuran): A Molecular Dynamics Study
Macromolecules ( IF 5.1 ) Pub Date : 2024-09-10 , DOI: 10.1021/acs.macromol.4c01173
Wenbin Jiang _{1,

2} , Danhong Wang _{1,

2} , Wenliang Li _{1,

2} , Jingping Zhang _{1,

2}

Affiliation

High Li⁺-transference number in polymer electrolytes is one of the key targets for the development of high-performance lithium-ion batteries (LIBs). In this work, we investigated the mechanism of lithium-ion transport in poly(tetrahydrofuran) (PTHF), compared with that in poly(ethylene oxide) (PEO), to elucidate the effect of oxygen density through molecular dynamics simulations. The effects of polymer chain properties, ion coordination and ion aggregation on diffusion coefficient and ion-transference number were studied in detail. The results show that the lower oxygen density in PTHF leads to a loose coordination structure of Li⁺ surrounded by the polymer chains. Meanwhile, Li⁺ and bis(trifluoromethane) sulfonamide (TFSI^–) mainly exist in the form of ion pairs in PTHF, and Li⁺ moves cooperatively with the drive of TFSI^–, which makes Li⁺ more prone to interchain hopping in PTHF than that in PEO. Under the combined influence of the above two factors, higher transference number of Li⁺ is obtained in the PTHF electrolyte. Our findings shed light on the effects of oxygen content in polymer substrates on ionic coordination conditions and transport mechanisms, providing valuable insights for the design of polymer electrolytes in high-performance solid-state LIBs.

中文翻译：

松配位聚四氢呋喃中的高 Li+ 转移数：分子动力学研究

聚合物电解质中的高Li ⁺迁移数是高性能锂离子电池（LIB）开发的关键目标之一。在这项工作中，我们研究了聚四氢呋喃（PTHF）中的锂离子传输机制，与聚环氧乙烷（PEO）中的锂离子传输机制进行比较，以通过分子动力学模拟阐明氧密度的影响。详细研究了聚合物链性质、离子配位和离子聚集对扩散系数和离子迁移数的影响。结果表明，PTHF中较低的氧密度导致聚合物链周围的Li ⁺配位结构松散。同时，Li ⁺和双(三氟甲烷)磺酰胺(TFSI ^– )在PTHF中主要以离子对的形式存在，Li ⁺在TFSI ^–的驱动下协同移动，这使得Li ⁺在PTHF中更容易发生链间跳跃。在PEO中。在上述两个因素的综合影响下，PTHF电解液中获得了较高的Li ⁺迁移数。我们的研究结果揭示了聚合物基质中氧含量对离子配位条件和传输机制的影响，为高性能固态锂离子电池中聚合物电解质的设计提供了宝贵的见解。

更新日期：2024-09-10

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