Connection between Lithium Coordination and Lithium Diffusion in [Pyr12O1 ][FTFSI] Ionic Liquid Electrolytes.
Connection between Lithium Coordination and Lithium Diffusion in [Pyr12O1 ][FTFSI] Ionic Liquid Electrolytes.
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DOI：
10.1002/cssc.201702288
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发表时间：
2018-06
期刊：
影响因子：
8.4
通讯作者：
G. Giffin;A. Moretti;Sangsik Jeong;Kartik Pilar;M. Brinkkötter;S. Greenbaum;M. Schönhoff;S. Passerini
中科院分区：
文献类型：
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作者：
G. Giffin;A. Moretti;Sangsik Jeong;Kartik Pilar;M. Brinkkötter;S. Greenbaum;M. Schönhoff;S. Passerini
与锂金属和锂离子电池中的 Li+ 稀释系统相比，使用高浓度离子液体电解质可提高 20°C 下的倍率性能和容量保持率。这项工作探索了本体电解质特性与分子组织之间的联系，以深入了解 Li+ 传输机制的浓度依赖性。低于 30 mol%，含 Li+ 物质主要是较小的复合物（一种 Li+ 阳离子），并且 Li+ 离子传输主要来自车辆传输。当浓度高于 30 mol% 时，粘度明显较高且电导率较低，含 Li+ 物质是小型和大型络合物（分别为一种和多于一种 Li+ 阳离子）的混合物。整体传导机制可能会发生变化，通过第一个 Li+ 溶剂化壳中的阴离子交换来促进结构扩散。良好的倍率性能可能直接受到较大 Li+ 络合物的存在的影响，较大的 Li+ 络合物促进 Li+ 离子传输（与 Li+ 络合物传输相反）并增加电极上 Li+ 的可用性。
The use of highly concentrated ionic liquid-based electrolytes results in improved rate capability and capacity retention at 20 °C compared to Li+ -dilute systems in Li-metal and Li-ion cells. This work explores the connection between the bulk electrolyte properties and the molecular organization to provide insight into the concentration dependence of the Li+ transport mechanisms. Below 30 mol %, the Li+ -containing species are primarily smaller complexes (one Li+ cation) and the Li+ ion transport is mostly derived from the vehicular transport. Above 30 mol %, where the viscosity is substantially higher and the conductivity lower, the Li+ -containing species are a mix of small and large complexes (one and more than one Li+ cation, respectively). The overall conduction mechanism likely changes to favor structural diffusion through the exchange of anions in the first Li+ solvation shell. The good rate performance is likely directly influenced by the presence of larger Li+ complexes, which promote Li+ -ion transport (as opposed to Li+ -complex transport) and increase the Li+ availability at the electrode.