Giffin Guinevere A, Moretti Arianna, Jeong Sangsik, Pilar Kartik, Brinkkötter Marc, Greenbaum Steven G, Schönhoff Monika, Passerini Stefano
Helmholtz-Institute Ulm (HIU), Helmholtzstrasse 11, 89081, Ulm, Germany.
Karlsruher Institute of Technology (KIT), P.O. Box 3640, 76021, Eggenstein-Leopoldshafen, Germany.
ChemSusChem. 2018 Jun 22;11(12):1981-1989. doi: 10.1002/cssc.201702288. Epub 2018 Feb 5.
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.
与锂金属电池和锂离子电池中的稀锂体系相比，使用高浓度离子液体基电解质可在20°C下提高倍率性能和容量保持率。这项工作探索了本体电解质性质与分子组织之间的联系，以深入了解锂传输机制的浓度依赖性。在30 mol%以下，含锂物种主要是较小的络合物（一个锂阳离子），锂离子传输主要源自载体传输。在30 mol%以上，粘度显著更高而电导率更低，含锂物种是小络合物和大络合物的混合（分别为一个和多个锂阳离子）。整体传导机制可能发生变化，有利于通过第一锂溶剂化壳层中阴离子的交换进行结构扩散。良好的倍率性能可能直接受到较大锂络合物的存在的影响，较大锂络合物促进锂离子传输（与锂络合物传输相反）并增加电极处的锂可用性。
