Jankowski Piotr, Dranka Maciej, Wieczorek Władysław, Johansson Patrik
Faculty of Chemistry, Warsaw University of Technology , ul. Noakowskiego 3, 00-664 Warsaw, Poland.
Department of Physics, Chalmers University of Technology , SE-412 96 Gothenburg, Sweden.
J Phys Chem Lett. 2017 Aug 3;8(15):3678-3682. doi: 10.1021/acs.jpclett.7b01160. Epub 2017 Jul 26.
Highly concentrated electrolytes based on Li-salts and chelating solvents, such as glymes, are promising as electrolytes for lithium batteries. This is due to their unique properties, such as higher electrochemical stabilities, compliance with high-voltage electrodes, low volatility and flammability, and inertness toward aluminum current collector corrosion. The nature of these properties originates from the molecular-level structure created in either solvate ionic liquids (SILs) or the less common ionic aggregates by disproportionation reactions. The nature of the anion plays a crucial role, and here, we present a computational study using TFSI and TDI anions as probes, revealing increasing differences upon increased salt concentration. TFSI-based electrolytes preferably form SILs, while TDI-based electrolytes form ionic aggregates. The latter lead to an unexpected creation of "free" cationic species even at (very) high salt concentrations and thus promise of ample lithium ion transport.
基于锂盐和螯合溶剂（如乙二醇二甲醚）的高浓度电解质，有望成为锂电池的电解质。这归因于它们独特的性质，如更高的电化学稳定性、与高压电极的兼容性、低挥发性和可燃性，以及对铝集流体腐蚀的惰性。这些性质的本质源于溶剂化离子液体（SILs）或通过歧化反应形成的不太常见的离子聚集体中产生的分子水平结构。阴离子的性质起着关键作用，在此，我们以双三氟甲磺酰亚胺（TFSI）和二异丁基酰胺（TDI）阴离子为探针进行了一项计算研究，揭示了随着盐浓度增加差异不断增大的情况。基于TFSI的电解质倾向于形成SILs，而基于TDI的电解质形成离子聚集体。后者即使在（非常）高盐浓度下也会意外产生“游离”阳离子物种，因此有望实现充足的锂离子传输。
