Becker Maximilian, Rentsch Daniel, Reber David, Aribia Abdessalem, Battaglia Corsin, Kühnel Ruben-Simon
Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland.
Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
Angew Chem Int Ed Engl. 2021 Jun 14;60(25):14100-14108. doi: 10.1002/anie.202103375. Epub 2021 May 14.
Water-in-salt electrolytes have successfully expanded the electrochemical stability window of aqueous electrolytes beyond 2 V. Further improvements in stability can be achieved by partially substituting water with either classical organic solvents or ionic liquids. Here, we study ternary electrolytes composed of LiTFSI, water, and imidazolium ionic liquids. We find that the LiTFSI solubility strongly increases from 21 mol kg in water to up to 60 mol kg in the presence of ionic liquid. The solution structure is investigated with Raman and NMR spectroscopy and the enhanced LiTFSI solubility is found to originate from a hydrotropic effect of the ionic liquids. The increased reductive stability of the ternary electrolytes enables stable cycling of an aqueous lithium-ion battery with an energy density of 150 Wh kg on the active material level based on commercially relevant Li Ti O and LiNi Mn Co O electrode materials.
盐包水电解质已成功将水性电解质的电化学稳定窗口扩展至超过2V。通过用传统有机溶剂或离子液体部分替代水，可以进一步提高稳定性。在此，我们研究了由双三氟甲烷磺酰亚胺锂（LiTFSI）、水和咪唑鎓离子液体组成的三元电解质。我们发现，在离子液体存在的情况下，LiTFSI的溶解度从在水中的21mol/kg大幅增加至高达60mol/kg。通过拉曼光谱和核磁共振光谱研究了溶液结构，发现增强的LiTFSI溶解度源于离子液体的促水溶效应。基于商业相关的LiTi₂O₄和LiNi₀.₅Mn₀.₃Co₀.₂O₂电极材料，三元电解质还原稳定性的提高使得水系锂离子电池在活性材料水平上能够实现150Wh/kg的能量密度稳定循环。
