Ni-rich LiNi_xCo_yMn_1-x-yO₂ (Ni-rich NCM; x ≥ 0.8, 0 < y < 1) is the most prominent cathode material to establish a practical high-energy density of lithium-ion batteries for electric vehicle. However, long-term capacity fading limits the commercial applications of Ni-rich NCM, especially at a high cut-off voltage (>4.3 V). Herein, 2,4-difluorobiphenyl (FBP) is proposed as a fluorine-based cathode electrolyte interphase (CEI)-forming additive for Ni-rich LiNi_0.83Co_0.11Mn_0.06O₂ (NCM83). The structural characteristics of FBP originate from the overcharge protection of biphenyl, whereas the fluorine atoms are preferable for high-voltage conditions. The addition of 1 wt% FBP to the electrolyte enhances the cycling stability at the 4.5 V cut-off voltage. Electrochemical impedance spectroscopy and rate capability results indicate a fast kinetics at the NCM83 surface with FBP additive upon the formation of a stable CEI. Images from scanning electron microscopy and transmission electron microscopy after 150 cycles of NCM83 show the thin deposit layer of CEI upon introduction of FBP. The X-ray photoelectron spectroscopy results demonstrate the suppression of electrolyte and salt decomposition. This work suggests an opportunity to develop a completely new functional additive by introducing a fluorine component to existing additives.

富镍 LiNi _x Co _y Mn _1-xy O ₂（富镍 NCM；x ≥ 0.8, 0 < y < 1）是最突出的正极材料，可用于建立实用的高能量密度锂离子电池车辆。然而，长期容量衰减限制了富镍 NCM 的商业应用，尤其是在高截止电压 (>4.3 V) 下。本文提出了 2,4-二氟联苯 (FBP) 作为富镍 LiNi _0.83 Co _0.11 Mn _0.06 O ₂的氟基正极电解质中间相 (CEI) 形成添加剂(NCM83)。FBP的结构特性源于联苯的过充电保护，而氟原子更适合高压条件。向电解质中添加 1 wt% FBP 可增强 4.5 V 截止电压下的循环稳定性。电化学阻抗谱和倍率性能结果表明，在形成稳定的 CEI 后，NCM83 表面具有 FBP 添加剂的快速动力学。NCM83 循环 150 次后，扫描电子显微镜和透射电子显微镜的图像显示引入 FBP 后 CEI 的薄沉积层。X 射线光电子能谱结果表明抑制了电解质和盐的分解。