Xie Yin, Meng Su, Chen Xiao, Liang Xiaoyu, Jin Yongcheng, Xiang Lan
Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
J Colloid Interface Sci. 2021 Jul 15;594:485-492. doi: 10.1016/j.jcis.2021.03.038. Epub 2021 Mar 15.
Li-rich layered oxides (LLOs) are promising cathode materials for Li-ion batteries owing to their high capacities (>250 mAh g), however, they suffered from severe capacity and voltage fading caused by irreversible oxygen loss and phase changes. Herein, the structural stability of single crystalline and polycrystalline LiNiMnCoO was compared in detail. It was found that the stability of oxidized oxygen ions on the near surface was improved in single crystals, which retarded oxygen loss from surface and surficial phase changes, possibly owing to the facet regulating and low surface curvature. In addition, the formation-migration of Mn, one of the crucial factors that caused capacity fading of LLOs, can be mitigated by increasing Ni ratio. Under the synergistic effect of low oxygen defects on the near surface and high Ni ratio, stable cycling performances and higher thermal stability were obtained.
富锂层状氧化物（LLOs）因其高容量（>250 mAh g）而成为锂离子电池颇具前景的正极材料，然而，它们因不可逆的氧损失和相变而遭受严重的容量和电压衰减。在此，详细比较了单晶和多晶LiNiMnCoO的结构稳定性。研究发现，单晶中近表面氧化氧离子的稳定性得到改善，这抑制了表面的氧损失和表面相变，可能归因于晶面调控和低表面曲率。此外，增加Ni比例可以减轻导致LLOs容量衰减的关键因素之一——Mn的形成-迁移。在近表面低氧缺陷和高Ni比例的协同作用下，获得了稳定的循环性能和更高的热稳定性。
