Ni-rich cathode material is one of the most promising materials for Li-ion batteries in electric vehicles. However, fading capacity, poor cyclic stability and high pH value are still major challenges, which suppress its practical application. In this study, spherical LiNi0.9Co0.08Al0.02O2 powders with 0.4 wt% TiO2 coating layer were prepared by impregnation–hydrolysis method. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) results show that TiO2 is uniformly coated on the surface of LiNi0.9Co0.08Al0.02O2 particle and slightly embedded into LiNi0.9Co0.08Al0.02O2 particles. After 100 cycles at 2.0C, 0.4 wt% TiO2-coated LiNi0.9Co0.08Al0.02O2 electrode delivers much higher discharge capacity retention (77.0%) than the pristine LiNi0.9Co0.08Al0.02O2 electrode (63.3%). The excellent cycling performance of 0.4 wt% TiO2-coated LiNi0.9Co0.08Al0.02O2 electrode at a high discharge ratio is due to a TiO2 coating layer which can effectively reduce the direct contact between cathode material and electrolyte, suppress the oxidation of electrolyte, improve electrical conductivity of the electrode and increase the stability of the structure. With the increase of current density, TCNC sample clearly exhibits enhanced cycling performance with higher capacity retention, and the capacity retention of TCNC increases by 22% at 2.0 C.

中文翻译：

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用于锂离子电池的具有增强循环性能的TiO2包覆LiNi0.9Co0.08Al0.02O2正极材料

富镍正极材料是电动汽车锂离子电池最有前途的材料之一。然而，褪色能力、循环稳定性差和高pH值仍然是主要挑战，抑制了其实际应用。在本研究中，通过浸渍-水解法制备了具有 0.4 wt% TiO2 涂层的球形 LiNi0.9Co0.08Al0.02O2 粉末。扫描电子显微镜（SEM）、高分辨透射电子显微镜（HRTEM）和 X 射线衍射（XRD）结果表明，TiO2 均匀包覆在 LiNi0.9Co0.08Al0.02O2 颗粒表面并轻微嵌入 LiNi0.9Co0 .08Al0.02O2 颗粒。在 2.0C 下循环 100 次后，0.4 wt% TiO2 涂层的 LiNi0.9Co0.08Al0.02O2 电极提供比原始 LiNi0.9Co0.08Al0.02O2 电极（63.3%）更高的放电容量保持率（77.0%）。0.4 wt% TiO2 包覆的 LiNi0.9Co0.08Al0.02O2 电极在高放电倍率下的优异循环性能是由于 TiO2 包覆层可以有效减少正极材料与电解液的直接接触，抑制电解液的氧化，提高电极的导电性，增加结构的稳定性。随着电流密度的增加，TCNC 样品明显表现出增强的循环性能和更高的容量保持率，并且在 2.0 C 时 TCNC 的容量保持率增加了 22%。提高电极的导电性，增加结构的稳定性。随着电流密度的增加，TCNC 样品明显表现出增强的循环性能和更高的容量保持率，并且在 2.0 C 时 TCNC 的容量保持率增加了 22%。提高电极的导电性，增加结构的稳定性。随着电流密度的增加，TCNC 样品明显表现出增强的循环性能和更高的容量保持率，并且在 2.0 C 时 TCNC 的容量保持率增加了 22%。