Abstract:

High-nickel material has high theoretical capacity, which can be used for promoting the energy density of LIBs. As a type of high-nickel material, LiNi_0.8Co_0.1Mn_0.1O₂ has been widely researched. Nevertheless, to pursuit higher energy density, the study on ultra-high-nickel materials (M_N>88%) is necessary. Unfortunately, the high content of Ni not only promotes the theoretical capacity, but also causes negative effects on the structure stability of high-nickel materials, which inhibits the practical application of high-nickel materials. Therefore, the preparation technology of ultra-high-nickel materials is significant. Herein, we prepared ultra-high-nickel materials with Ni content of 88%, 90%, 92%, 94%, and 98%, then the relevant physiochemical properties as well as electrochemical performances were investigated. The effects of the increased Ni content on the capacity and the structural stability of high-nickel materials were verified. Furthermore, the ultra-high-nickel material with Ni content of 90% (Ni90) was selected, and the effect of different sintering temperatures was evaluated. It was found that the particle sizes increased as thewith rising temperature, and 750℃ leads led to the best rate and cycling performances of Ni90, in which the particle sizes and the structural stability achieved a balance. Meanwhile, it was revealed that an appropriate sintering temperature was crucial to prepare ultra-high-nickel materials which exhibited both excellent performances and stability.

Key words: electrochemistry, preparation, high-nickel material, cathode, lithium-ion battery

摘要：

高镍三元正极材料具有很高的理论容量，可被用于提高锂离子电池体系的能量。目前研究较多的高镍材料是镍摩尔分数在三元素中占比为80%的LiNi_0.8Co_0.1Mn_0.1O₂，但是为了追求更高的能量密度，具有更高镍摩尔分数（镍摩尔分数＞88%）的超高镍材料也需要被研究。然而，镍含量的提升对材料结构稳定性造成的负面影响阻碍了高镍材料的实际应用。因此，优化高镍材料的制备工艺十分重要。本工作首先制备了镍摩尔分数为88%、90%、92%、94%以及98%的超高镍材料，探究了它们的基本物理化学性质与电化学性能，验证了镍摩尔分数提升对于材料容量和结构稳定性带来的影响。进一步地，本工作选取了镍摩尔分数为90%的高镍材料（Ni90），着重探究了烧结温度对其性质的影响，发现Ni90材料颗粒会随着烧结温度的上升而增大，而在750℃的适宜烧结温度下，材料能在结构和颗粒尺寸上达到平衡，得到倍率和循环综合性能最好的Ni90材料。同时，对于不同镍含量的材料，也需要选择适中的温度进行烧结，才能兼顾材料的性能与稳定性。

关键词: 电化学, 制备, 高镍材料, 正极, 锂离子电池