To design safe and electrochemically stable electrolytes for lithium-ion batteries, this study describes the synthesis and the utilization of new deep eutectic solvents (DESs) based on the mixture of 2,2,2-trifluoroacetamide (TFA) with a lithium salt (LiTFSI, lithium bis[(trifluoromethane)sulfonyl]imide). These prepared DESs were characterized in terms of thermal properties, ionic conductivity, viscosity, and electrochemical properties. Based on the appearance of the product and DSC measurements, it appears that this system is liquid at room temperature for LiTFSI mole fraction ranging from 0.25 to 0.5. At χ_LiTFSI = 0.25, DESs exhibited favorable electrolyte properties, such as thermal stability (up to 148 °C), relatively low viscosity (42.2 mPa.s at 30 °C), high ionic conductivity (1.5 mS.cm^–1 at 30 °C), and quite large electrochemical stability window up to 4.9–5.3 V. With these interesting properties, selected DES was diluted with slight amount of ethylene carbonate (EC). Different amounts of EC (x = 0–30 %wt) were used to form hybrid electrolytes for battery testing with high voltage LiMn₂O₄ cathode and Li anode. The addition of the EC solvent into DES expectedly aims at enhancing the battery cycling performance at room temperature due to reducing the viscosity. Preliminary results tests clearly show that LiTFSI-based DES can be successfully introduced as an electrolyte in the lithium-ion batteries cell with a LiMn₂O₄ cathode material. Among all of the studied electrolytes, DES (LiTFSI: TFA = 4:1 + 10 %wt EC) is the most promising. The EC-based system exhibited a good specific capacity of 102 mAh.g^–1 at C/10 with the theoretical capacity of 148 mAh.g^–1 and a good cycling behavior maintaining at 84% after 50 cycles.

中文翻译：

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基于双[(三氟甲基)磺酰基]酰亚胺锂 (LiTFSI) 和 2,2,2-三氟乙酰胺 (TFA) 的深度共晶溶剂作为具有 LiMn2O4 正极的高压锂离子电池的有前景的电解质


为了设计用于锂离子电池的安全且电化学稳定的电解质，本研究描述了基于 2,2,2-三氟乙酰胺 (TFA) 与锂盐 (LiTFSI) 混合物的新型低共熔溶剂 (DES) 的合成和利用，双[(三氟甲烷)磺酰基]亚胺锂)。对这些制备的 DES 进行了热性能、离子电导率、粘度和电化学性能的表征。根据产品的外观和 DSC 测量，该系统在室温下呈液态，LiTFSI 摩尔分数范围为 0.25 至 0.5。当 χ _LiTFSI = 0.25 时，DES 表现出良好的电解质特性，例如热稳定性（高达 148 °C）、相对较低的粘度（30 °C 时为 42.2 mPa.s）、高离子电导率（30 °C 时为 1.5 mS.cm ^–1） °C），以及高达 4.9-5.3 V 的相当大的电化学稳定性窗口。凭借这些有趣的特性，选择的 DES 用少量的碳酸亚乙酯 (EC) 稀释。使用不同量的 EC（ x = 0–30%wt）形成混合电解质，用于高电压 LiMn ₂ O ₄正极和 Li 负极的电池测试。在 DES 中添加 EC 溶剂有望通过降低粘度来提高室温下的电池循环性能。初步结果测试清楚地表明，基于LiTFSI的DES可以成功地作为电解质引入到具有LiMn ₂ O ₄正极材料的锂离子电池中。在所有研究的电解质中，DES (LiTFSI: TFA = 4:1 + 10 %wt EC) 是最有前途的。基于 EC 的系统表现出 102 mAh 的良好比容量。g ^–1 at C/10，理论容量为148 mAh.g ^–1 ，循环性能良好，50次循环后仍保持在84%。