Abstract The layered Li-rich Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials have been synthesized by a facile approach and subsequently modified with different amount of Al2O3 nano layer. The microstructure and electrochemical performance of the pristine and Al2O3 coated samples were investigated systematically. It is found that the pristine particles are uniformly coated with Al2O3 layer. In particular, the 3 wt% Al2O3-coated cathode delivers the highest initial discharge capacity of 317.9 mAhg−1 at 25 mAg−1 in the voltage window 2.0–4.8 V, and best rate performance (317.9 mAhg−1 at 0.1 C, 105.6 mAhg−1 at 10 C), and best cyclability (discharge capacity of 164 mAhg−1 at 2 C after 200 cycles with capacity retention of 86.3%), which is much better than that of the pristine cathode (discharge capacity of 124 mAhg−1 at 2 C after 200 cycles with capacity retention of 73.3%). Electrochemical impedance spectroscopy (EIS) shows that the Al2O3 coating can reduce the charge transfer resistance during the cycle, which is attributed to the suppression of the side reactions and the stability of the surface structure of the active materials by Al2O3 oxide coating. These findings provide a research direction for solving serious defects such as large initial irreversible capacity loss and poor cycle stability of lithium-rich cathode materials for lithium ion batteries.

中文翻译：

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Al2O3表面涂层对Li1.2Ni0.13Co0.13Mn0.54O2正极材料电化学性能的改善

摘要 通过简便的方法合成了层状富锂Li1.2Ni0.13Co0.13Mn0.54O2正极材料，并随后用不同量的Al2O3纳米层进行改性。系统地研究了原始和 Al2O3 涂层样品的微观结构和电化学性能。发现原始颗粒均匀地包覆有 Al2O3 层。特别是，3 wt% Al2O3 涂层阴极在 2.0-4.8 V 电压窗口内在 25 mAg-1 下提供最高的初始放电容量 317.9 mAhg-1，以及最佳倍率性能（317.9 mAhg-1 at 0.1 C, 105.6 mAhg-1 at 10 C)，以及最佳循环性能（200 次循环后 2 C 放电容量为 164 mAhg-1，容量保持率为 86.3%），这远优于原始正极（200 次循环后 2 C 的放电容量为 124 mAhg-1，容量保持率为 73.3%）。电化学阻抗谱（EIS）表明，Al2O3涂层可以降低循环过程中的电荷转移电阻，这归因于Al2O3氧化物涂层抑制了副反应和活性材料表面结构的稳定性。这些发现为解决锂离子电池富锂正极材料初始不可逆容量损失大、循环稳定性差等严重缺陷提供了研究方向。这归因于 Al2O3 氧化物涂层抑制副反应和活性材料表面结构的稳定性。这些发现为解决锂离子电池富锂正极材料初始不可逆容量损失大、循环稳定性差等严重缺陷提供了研究方向。这归因于 Al2O3 氧化物涂层抑制副反应和活性材料表面结构的稳定性。这些发现为解决锂离子电池富锂正极材料初始不可逆容量损失大、循环稳定性差等严重缺陷提供了研究方向。