探索富镍层状阴极的热驱动的结构和化学降解，这一成果由美国阿贡国家实验室的Khalil Amine、Gui-Liang Xu和清华大学Minggao Ouyang小组经过不懈努力而取得。2020年11月4日出版的《美国化学会志》发表了这一最新研究成果。

通过在富镍阴极LiNi_0.83Co_0.11Mn_0.06O₂ 中的Co/Mn交换，研究人员证明了深度脱锂的NCM阴极的化学和结构稳定性主要由Co而不是广泛报道的Mn而决定的。Operando同步加速器x射线表征与原位质谱分析表明，Co⁴⁺先于Ni⁴⁺被还原，从而可以通过占据四面体位点延长Ni的迁移，因此，推迟氧气释放和热故障。相比之下，Mn本身是稳定的，但几乎没有稳定的Ni⁴⁺。

他们的结果强调了评估组成调整的内在作用对富镍/无钴层状氧化阴极材料的重要性，以确保高能锂离子电池的安全使用。

据悉，层状LiNi_xCo_yMn_1-x-yO₂ (NCM)阴极自身热稳定性差和由相关氧气释放引发的放热副反应是阻碍其大规模植入的主要安全威胁。在NCM家族中，人们普遍认为镍是影响稳定性的麻烦制造者，而锰一直被视为一个结构稳定剂，同时钴的作用仍然模糊。

附：英文原文

Title: Probing the Thermal-Driven Structural and Chemical Degradation of Ni-Rich Layered Cathodes by Co/Mn Exchange

Author: Xiang Liu, Gui-Liang Xu, Liang Yin, Inhui Hwang, Yan Li, Languang Lu, Wenqian Xu, Xuequan Zhang, Yanbin Chen, Yang Ren, Cheng-Jun Sun, Zonghai Chen, Minggao Ouyang, Khalil Amine

Issue&Volume: November 4, 2020

Abstract: The intrinsic poor thermal stability of layered LiNi_xCo_yMn_1–x–yO₂ (NCM) cathodes and the exothermic side reactions triggered by the associated oxygen release are the main safety threats for their large-scale implantation. In the NCM family, it is widely accepted that Ni is the stability troublemaker, while Mn has long been considered as a structure stabilizer, whereas the role of Co remains elusive. Here, via Co/Mn exchange in a Ni-rich LiNi_0.83Co_0.11Mn_0.06O₂ cathode, we demonstrate that the chemical and structural stability of the deep delithiated NCM cathodes are significantly dominated by Co rather than the widely reported Mn. Operando synchrotron X-ray characterization coupling with in situ mass spectrometry reveal that the Co⁴⁺ reduces prior to the reduction of Ni⁴⁺ and could thus prolong the Ni migration by occupying the tetrahedra sites and, hence, postpone the oxygen release and thermal failure. In contrast, the Mn itself is stable, but barely stabilizes the Ni⁴⁺. Our results highlight the importance of evaluating the intrinsic role of compositional tuning on the Ni-rich/Co-free layered oxide cathode materials to guarantee the safe operation of high-energy Li-ion batteries.

DOI: 10.1021/jacs.0c09961

Source: https://pubs.acs.org/doi/10.1021/jacs.0c09961