Stabilizing Interfaces in High-Temperature NCM811-Li Batteries via Tuning Terminal Alkyl Chains of Ether Solvents |
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Authors: | Dr Zhijie Wang Changsheng Chen Danni Wang Dr Ye Zhu Dr Biao Zhang |
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Institution: | 1. Department of Applied Physics & Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, 999077 P. R. China;2. Department of Applied Physics & Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, 999077 P. R. China
These authors contributed equally to this work. |
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Abstract: | Ether electrolytes are promising for lithium metal batteries. Despite the intensive research in recent years, most state-of-the-art ether electrolytes still cannot form reliable electrode-electrolyte interfaces in NCM811-Li batteries at diluted concentrations, especially in those operating at elevated temperatures. We report a simple but effective strategy to break this bottleneck and stabilize interfaces in high-temperature NCM811-Li batteries in ether electrolytes. We propose that by gradually extending the terminal groups of glycol diethers from methyl groups to n-butyl groups, the comprehensive stability of ether electrolytes is improved. An anion-dominated solvation structure is realized at a concentration of 1 M. Accordingly, the electrode-electrolyte interactions are suppressed, and a thinner, denser, and more inorganic-rich solid- /cathode-electrolyte interface is achieved. Additionally, the surface phase transition and structural degradation of NCM811 cathode are alleviated. Consequently, in the ethylene glycol dibutyl ether-based electrolyte, the Coulombic efficiency for Li−Cu cells working at 60 °C is boosted to 99.41 % with a cycling life of over 200 cycles. The lifespan of high-temperature NCM811-Li cells is prolonged by more than 400 % with a stable average Coulombic efficiency of 99.77 % at quasi-practical conditions of 50 μm Li, lean electrolyte of 10 μL mAh−1, and medium-high cathode loading of >2.2 mAh cm−2. |
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Keywords: | Alkoxy Groups Electrode-Electrolyte Interfaces Ether Electrolytes High-Temperature NCM811-Li Batteries Terminal Alkyl Chains |
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