Abstract Layered lithium/manganese-rich oxides (LMR) receive much attention due to its high specific capacity (∼300 mAh g-1). However, the serious capacity degradation during cycling hinders the commercial application of the LMR. Herein, 3-cyano-5-fluorophenylboronic acid (CFBA) was applied as an electrolyte additive for enhancing the cycling stability of LMR at high voltage. Linear sweep voltammetry (LSV), density function theory (DFT) calculations and the initial charge dQ/dV profiles indicate that the preferential oxidation of CFBA can improve the oxidative stability of electrolyte. By adding 0.7 wt% CFBA into standard (STD) electrolyte (1 M LiPF6 in EC:EMC:DMC = 1:1:1, by weight), the LMR/Li half-cell delivered a discharge capacity of 245 mAh g-1 with a capacity retention of 88.4% after 200 cycles at 0.5C, while only 68 mAh g-1 with 25.2% retention in STD electrolyte. Further characterizations and theoretical calculation illustrate that CFBA can effectively eliminate the harmful HF, which improve the electrochemical performance. More importantly, the CFBA participates in the formation of a thin and uniform protective cathode-electrolyte interface (CEI) film on the surface of LMR, which effectively suppresses electrolyte decomposition and protects the structural integrity of LMR.

中文翻译：

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3-氰基-5-氟苯硼酸作为电解质添加剂提高Li1.2Mn0.54Ni0.13Co0.13O2正极在高压下的循环稳定性

摘要 层状富锂/锰氧化物（LMR）因其高比容量（~300 mAh g-1）而备受关注。然而，循环过程中严重的容量下降阻碍了LMR的商业应用。在此，3-氰基-5-氟苯基硼酸（CFBA）被用作电解质添加剂，以提高LMR在高电压下的循环稳定性。线性扫描伏安法 (LSV)、密度函数理论 (DFT) 计算和初始电荷 dQ/dV 曲线表明，CFBA 的优先氧化可以提高电解液的氧化稳定性。通过在标准 (STD) 电解液中添加 0.7 wt% CFBA（EC:EMC:DMC 中的 1 M LiPF6 = 1:1:1，按重量计），LMR/Li 半电池提供了 245 mAh g-1 的放电容量在 0.5C 下循环 200 次后容量保持率为 88.4%，而 25 时仅为 68 mAh g-1。在 STD 电解液中保留 2%。进一步的表征和理论计算表明，CFBA 可以有效消除有害的 HF，从而提高电化学性能。更重要的是，CFBA参与在LMR表面形成薄而均匀的保护性阴极-电解质界面（CEI）膜，有效抑制电解质分解并保护LMR的结构完整性。