Chen Lu, Zhang Qing, Song Chunlei, Jiang Yanxin, Sheng Xitong, Pan Hongji, Yang Liu, Wu Shumin, Zeng Lin, Sun Delong, Wang Chong, Wang Tianshuai, Li Yiju, Zhao Tianshou
Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Department of Mechanical and Energy Engineering-Jiahua Chemicals. Inc. Joint Lab, Southern University of Science and Technology, Shenzhen, 518055, China.
Angew Chem Int Ed Engl. 2025 Apr 7;64(15):e202422791. doi: 10.1002/anie.202422791. Epub 2025 Feb 12.
Electrolyte chemistries are crucial for achieving high cycling performance and high energy density in lithium metal batteries. The localized high-concentration electrolytes (LHCEs) exhibit good performance in lithium metal batteries. However, understanding how the intermolecular interactions between solvents and diluents in the electrolyte regulate the solvation structure and interfacial layer structure remains limited. Here, we reported a new LHCE in which strong hydrogen bonding between diluents and solvents alters the conformation and polarity of "flexible" solvent molecules, thereby effectively regulating the solvation structure of Li ion and promoting the formation of robust electrode interfaces. The endpoint H of the "flexible" chain O-CH-CH of the 2,5-dimethyltetrahydrofuran (2,5-THF) solvent and the F of the benzotrifluoride (BTF) diluent can form strong hydrogen bonds, which expand the maximum bond angle of the 2,5-THF molecule from 119° to 123°. The expanded bond angle increases the steric hindrance of the 2,5-THF molecule and decreases its polarity. This leads to an increase in the anion content within the solvation structure, which in turn enhances the performance of both the lithium metal anode and the sulfurized polyacrylonitrile (SPAN) cathode. As a result, the lithium metal anode shows a Coulombic efficiency (CE) of as high as 99.4 %. The assembled Li||SPAN battery based on our developed LHCE exhibits impressive stability with an average CE of 99.8 % over 700 cycles. Moreover, the Li||SPAN pouch cell can be stably cycled with a high energy density of 301.4 Wh kg. This molecular-level understanding of the correlation between molecular interactions and solvation structures provides new insights into the design of advanced LHCEs for high-performance lithium metal batteries.
电解质化学对于锂金属电池实现高循环性能和高能量密度至关重要。局部高浓度电解质（LHCEs）在锂金属电池中表现出良好性能。然而，对于电解质中溶剂和稀释剂之间的分子间相互作用如何调节溶剂化结构和界面层结构的理解仍然有限。在此，我们报道了一种新型LHCE，其中稀释剂与溶剂之间的强氢键改变了“柔性”溶剂分子的构象和极性，从而有效调节锂离子的溶剂化结构并促进形成坚固的电极界面。2,5 - 二甲基四氢呋喃（2,5 - THF）溶剂的“柔性”链O - CH - CH的端点H与三氟甲苯（BTF）稀释剂的F可形成强氢键，这将2,5 - THF分子的最大键角从119°扩大到123°。扩大的键角增加了2,5 - THF分子的空间位阻并降低了其极性。这导致溶剂化结构内阴离子含量增加，进而提高了锂金属负极和硫化聚丙烯腈（SPAN）正极的性能。结果，锂金属负极的库仑效率（CE）高达99.4%。基于我们开发的LHCE组装的Li||SPAN电池表现出令人印象深刻的稳定性，在700次循环中平均CE为99.8%。此外，Li||SPAN软包电池可以以301.4 Wh kg的高能量密度稳定循环。这种对分子相互作用与溶剂化结构之间相关性的分子水平理解为高性能锂金属电池的先进LHCE设计提供了新的见解。
