Nickel-riched layered oxide cathode is one of the most promising cathode materials for high energy density lithium-ion batteries, but the capacity decay and poor cycling stability due to the occurrence of side reactions at the electrode-electrolyte interface are huge obstacles preventing its performance. Surface coating is an effective method to solve this problem. In this paper, nanoscale LiF films were deposited on the surface of NiCoMnO (NCM811) by magnetron sputtering, which effectively improved the electrochemical performance of NCM811 in half-cells. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) showed that LiF was uniformly deposited onto the electrode surface and was not embedded in the cathode particles. After 100 cycles at 0.5C, the discharge specific capacity of the coated modified NCM was 181.82 mAh/g with a retention rate of 93.95%, which was much higher than that of the original NCM811 at 160.84 mAh/g with a capacity retention rate of 83.11%, while the capacity remained basically unchanged. In addition, the modified rate capability was also significantly improved, with the discharge specific capacity of the modified sample at 5C being 167.26 mAh/g, which was 12.45% higher than that of the uncoated sample at 148.73 mAh/g. The deposited LiF film can protect the electrode interface, inhibit the decomposition of electrolyte and thus protect the positive electrode, and stabilize the structure of the particles.

中文翻译：

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通过磁控溅射在 NCM 电极表面涂覆超薄 LiF 薄膜，以优化结构稳定性和循环性能

富镍层状氧化物正极是最有前途的高能量密度锂离子电池正极材料之一，但由于电极-电解质界面发生副反应导致的容量衰减和循环稳定性差是其性能的巨大障碍。表面涂层是解决这一问题的有效方法。本文通过磁控溅射在NiCoMnO（NCM811）表面沉积纳米级LiF薄膜，有效提高了NCM811在半电池中的电化学性能。扫描电子显微镜（SEM）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）表明LiF均匀沉积在电极表面上，并且没有嵌入阴极颗粒中。0.5C循环100次后，包覆改性NCM的放电比容量为181.82 mAh/g，容量保持率为93.95%，远高于原NCM811的160.84 mAh/g，容量保持率为83.11%，而运力基本保持不变。此外，改性后的倍率性能也得到显着提升，改性后的样品5C放电比容量为167.26mAh/g，比未涂层样品的148.73mAh/g提高了12.45%。沉积的LiF薄膜可以保护电极界面，抑制电解液的分解从而保护正极，并稳定颗粒的结构。