Wang Chunyang, Wang Xuelong, Zhang Rui, Lei Tianjiao, Kisslinger Kim, Xin Huolin L
Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, USA.
Chemistry Division, Brookhaven National Laboratory, Upton, NY, USA.
Nat Mater. 2023 Feb;22(2):235-241. doi: 10.1038/s41563-022-01461-5. Epub 2023 Jan 26.
High-Ni-content layered materials are promising cathodes for next-generation lithium-ion batteries. However, investigating the atomic configurations of the delithiation-induced complex phase boundaries and their transitions remains challenging. Here, by using deep-learning-aided super-resolution electron microscopy, we resolve the intralayer transition motifs at complex phase boundaries in high-Ni cathodes. We reveal that an O3 → O1 transformation driven by delithiation leads to the formation of two types of O1-O3 interface, the continuous- and abrupt-transition interfaces. The interfacial misfit is accommodated by a continuous shear-transition zone and an abrupt structural unit, respectively. Atomic-scale simulations show that uneven in-plane Li distribution contributes to the formation of both types of interface, and the abrupt transition is energetically more favourable in a delithiated state where O1 is dominant, or when there is an uneven in-plane Li distribution in a delithiated O3 lattice. Moreover, a twin-like motif that introduces structural units analogous to the abrupt-type O1-O3 interface is also uncovered. The structural transition motifs resolved in this study provide further understanding of shear-induced phase transformations and phase boundaries in high-Ni layered cathodes.
高镍含量的层状材料是下一代锂离子电池很有前景的阴极材料。然而，研究脱锂诱导的复杂相界的原子构型及其转变仍然具有挑战性。在此，通过使用深度学习辅助的超分辨率电子显微镜，我们解析了高镍阴极中复杂相界处的层内转变模式。我们发现，脱锂驱动的O3→O1转变导致形成两种类型的O1 - O3界面，即连续转变界面和突变界面。界面失配分别由连续的剪切转变区和突变结构单元来调节。原子尺度模拟表明，面内锂分布不均匀有助于两种类型界面的形成，并且在O1占主导的脱锂状态下，或者在脱锂的O3晶格中面内锂分布不均匀时，突变转变在能量上更有利。此外，还发现了一种孪晶状模式，它引入了类似于突变型O1 - O3界面的结构单元。本研究中解析的结构转变模式为深入理解高镍层状阴极中的剪切诱导相变和相界提供了帮助。
