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首页> 外文期刊>Applied Magnetic Resonance >Multinuclear NMR Study of Structure and Mobility in Cyclic Model Lithium Conducting Systems
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Multinuclear NMR Study of Structure and Mobility in Cyclic Model Lithium Conducting Systems

机译：循环模型锂传导系统的结构和迁移率的多核NMR研究

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摘要

The transport of the lithium ions is the basis of lithium ion conductivity of currently used electrolytes. Understanding how the transport of lithium ions within the matrix is influenced by the interactions with solvating moieties is needed to improve their performance. Along these lines well-defined model compounds based on cyclotriphosphazene (CTP) and hexaphenylbenzene (HPB) cores, bearing side groups of ethylene carbonate, a common solvent for lithium salts used as electrolytes in Li-ion batteries (Thielen et al. Chem. Mater, 23, 2120, 2011) and blended with different amounts of Lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) have been studied by multinuclear nuclear magnetic resonance (NMR) spectroscopy. The local dynamics of the matrix was probed by ~1H and ~(31)P NMR, while the local dynamics of the Li~+ cations was unraveled by ~7Li and ~(13)C NMR. Transport of both ions was studied by pulsed-field gradient (PFG) NMR. Based on the different temperature dependences of the dynamics the bulk ion transport is not attributed to local dynamics, but to translational diffusion best characterized by PFG NMR. Although the glass transition temperatures of the blends are low, their conductivities are only in the range of typical polymer electrolytes. The results of NMR spectroscopy are in accord with the conjecture that the coordination between the cyclic carbonate functionality and the Li~+-ion is too tight to allow for fast ion dynamics.
机译：锂离子的传输是当前使用的电解质的锂离子电导率的基础。需要了解锂离子在基质中的传输如何受溶剂化部分的相互作用影响，以改善其性能。沿着这些思路，基于环三磷腈（CTP）和六苯基苯（HPB）核的定义明确的模型化合物带有碳酸亚乙酯的侧基，碳酸亚乙酯是锂离子电池中用作电解质的锂盐的常用溶剂（Thielen等人，Chem。Mater ，23，2120，2011），并通过多核核磁共振（NMR）光谱研究了掺入不同量的双（三氟甲磺酰基）酰亚胺锂（LiTFSI）。通过〜1H和〜（31）P NMR探测了基体的局部动力学，而~~ 7Li和〜（13）C NMR揭示了Li〜+阳离子的局部动力学。通过脉冲场梯度（PFG）NMR研究了两种离子的传输。基于动力学的不同温度依赖性，体离子的迁移不是归因于局部动力学，而是归因于PFG NMR最好的平移扩散。尽管共混物的玻璃化转变温度低，但是它们的电导率仅在典型的聚合物电解质的范围内。 NMR光谱学的结果符合这样的推测，即环状碳酸酯官能团与Li〜+离子之间的配位关系太紧密，无法实现快速的离子动力学。

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