Surface coating is a crucial method to mitigate the aging problem of high‐Ni cathode active materials (CAMs). By avoiding the direct contact of the CAM and the electrolyte, side reactions are hindered. Commonly used techniques like wet or ALD coating are time consuming and costly. Therefore, a more cost‐effective coating technique is desirable. Herein, a facile and fast dry powder coating process for CAMs with nanostructured fumed metal oxides are reported. As the model case, the coating of high‐Ni NMC (LiNi_0.7Mn_0.15Co_0.15O₂) by nanostructured fumed Al₂O₃ is investigated. A high coverage of the CAM surface with an almost continuous coating layer is achieved, still showing some porosity. Electrochemical evaluation shows a significant increase in capacity retention, cycle life and rate performance of the coated NMC material. The coating layer protects the surface of the CAM successfully and prevents side reactions, resulting in reduced solid electrolyte interface (SEI) formation and charge transfer impedance during cycling. A mechanism on how the coating layer enhances the cycling performance is hypothesized. The stable coating layer effectively prevents crack formation and particle disintegration of the NMC. In depth analysis indicates partial formation of Li_xAl₂O₃/LiAlO₂ in the coating layer during cycling, enhancing lithium ion diffusivity and thus, also the rate performance.

中文翻译：

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纳米结构的气相氧化铝（Al2O3）用于高镍阴极材料的快速干涂方法可改善锂离子电池的性能

表面涂层是缓解高Ni阴极活性材料（CAM）老化问题的关键方法。通过避免CAM与电解质的直接接触，可以防止副反应。诸如湿涂或ALD涂层之类的常用技术既耗时又昂贵。因此，需要一种更具成本效益的涂层技术。本文中，报道了具有纳米结构的气相金属氧化物的CAM的简便且快速干燥的粉末涂覆方法。作为模型案例，采用纳米结构的气相Al ₂ O ₃涂覆高Ni NMC（LiNi _0.7 Mn _0.15 Co _0.15 O ₂）涂层被调查。用几乎连续的涂层实现了CAM表面的高覆盖率，仍然显示出一定的孔隙率。电化学评估显示，涂覆的NMC材料的容量保持率，循环寿命和速率性能显着提高。涂层成功地保护了CAM的表面并防止了副反应，从而减少了固体电解质界面（SEI）的形成以及循环过程中电荷转移的阻抗。假设了关于涂层如何增强循环性能的机理。稳定的涂层有效地防止了NMC的裂纹形成和颗粒崩解。深入分析表明，部分形成了Li _x Al ₂ O ₃ / LiAlO ₂ 在循环过程中，涂层中的锂离子会增加锂离子的扩散率，从而提高速率性能。