In view of the advantageous merits of LiNi_0.8Co_0.15Al_0.05O₂ (NCA), i.e., high voltage and decent specific capacity, an impressive electrolyte film-forming additive, methyl-3-fluorothiophene-2-carboxylate (MFC), is put forward to remarkably improve the cycle performance of NCA cathodes toward high energy density lithium-ion batteries (LIBs). Theoretical calculation and experimental investigation both reveal that MFC is more readily oxidized to construct a cathode electrolyte interphase (CEI) on the surface of NCA cathode. Spectroscopy and microscopy data display that a MFC-derived CEI layer is thin, homogeneous, and conformally covers on the NCA surface, maintains the NCA structural integrity without visible microcracks, and protects the NCA cathode from electrolyte corrosion with alleviated dissolution of Ni and Co. Electrochemical properties show that the NCA/Li half-cell with a 5 wt % MFC-containing electrolyte delivers a higher discharge capacity with a much superior capacity retention of 148.6 mA h g^–1/85.5% than that of base electrolyte (121.2 mA h g^–1/71.0%) after 150 cycles at 1 C. This work indicates that MFC can work as an effective film-forming additive for high-voltage NCA and provides precious insights and theoretical guidance to the development of advanced electrolyte additives for high energy density LIBs.

中文翻译：

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氟化噻吩基电解质添加剂可为高压 LiNi0.8Co0.15Al0.05O2 阴极提供具有保形均匀性的稳健阴极电解质界面

鉴于LiNi _0.8 Co _0.15 Al _0.05 O ₂ (NCA)的高电压和良好的比容量等优点，人们提出了一种令人印象深刻的电解质成膜添加剂——3-氟噻吩-2-甲酸甲酯(MFC)。提出显着提高高能量密度锂离子电池（LIB）NCA正极的循环性能。理论计算和实验研究均表明，MFC更容易被氧化，在NCA正极表面构建正极电解质中间相（CEI）。光谱和显微镜数据显示，MFC 衍生的 CEI 层薄而均匀，并保形地覆盖在 NCA 表面上，保持 NCA 结构完整性，没有可见的微裂纹，并保护 NCA 阴极免受电解质腐蚀，同时减少 Ni 和 Co 的溶解。电化学性能表明，具有 5 wt% MFC 电解质的 NCA/Li 半电池可提供更高的放电容量，其容量保持率比基础电解质 (121.2 mA hg –1)优越得多，为 148.6 mA hg ^{–1 /85.5% 。 1} /71.0%）在1 C下循环150次后。这项工作表明MFC可以作为高压NCA的有效成膜添加剂，并为高能量密度LIB的先进电解质添加剂的开发提供宝贵的见解和理论指导。