Lithium metal batteries (LMBs) combined with a high-voltage nickel-rich cathode show great potential in meeting the growing need for high energy density. The lack of advanced electrolytes has been a major obstacle in the commercialization of high-voltage lithium metal batteries (LMBs), as these electrolytes need to effectively support both a stable lithium metal anode (LMA) and a high-voltage cathode (>4 V vs Li⁺/Li). In this work, by extending the two terminal methyl groups in DIGDME and TEGDME to n-butyl groups, we design a new weakly solvating electrolyte (2 M LIFSI+TEGDBE) that enables the stable cycling of NMC83 (LiNi_0.83Co_0.12Mn_0.05O₂) cathodes. The NMC83 cell exhibits a high and stable Coulombic efficiency (CE) of over 99%, as well as capacity retention of approximately 99.8% after 100 cycles at 0.3 C. X-ray photoelectron spectroscopy analysis (XPS) and high-resolution transmission electron microscope (HRTEM) images revealed that the anion species decomposed first, resulting in the formation of a cathode–electrolyte interface (CEI) film predominantly consisting of decomposition products from the anions on the positive electrode surface. This work links the functional group of solvents with the solvation structure and electrochemical performance of ether-based electrolytes, providing a distinctive sight to design advanced electrolytes for high-energy-density LMBs.

中文翻译：

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调节醚溶剂的末端烷基链以稳定三元锂电池中的电极/电解质界面


锂金属电池（LMB）与高压富镍正极相结合，在满足日益增长的高能量密度需求方面显示出巨大潜力。缺乏先进的电解质一直是高压锂金属电池（LMB）商业化的主要障碍，因为这些电解质需要有效支持稳定的锂金属阳极（LMA）和高压阴极（>4V）与李 ⁺ /Li)。在这项工作中，通过将DIGDME和TEGDME中的两个末端甲基延伸为正丁基，我们设计了一种新型弱溶剂化电解质（2 M LIFSI+TEGDBE），使NMC83（LiNi _0.83 Mn _0.05 O ₂ ）阴极。 NMC83电池表现出超过99%的高且稳定的库仑效率（CE），以及在0.3 C下循环100次后容量保持率约为99.8%。X射线光电子能谱分析（XPS）和高分辨率透射电子显微镜（HRTEM）图像显示，阴离子物质首先分解，导致形成阴极-电解质界面（CEI）膜，主要由正极表面阴离子的分解产物组成。这项工作将溶剂的官能团与醚基电解质的溶剂化结构和电化学性能联系起来，为设计用于高能量密度LMB的先进电解质提供了独特的视角。