Kaewmala Songyoot, Limphirat Wanwisa, Yordsri Visittapong, Kim Hyunwoo, Muhammad Shoaib, Yoon Won-Sub, Srilomsak Sutham, Limthongkul Pimpa, Meethong Nonglak
Materials Science and Nanotechnology Program, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen, 40002, Thailand.
Synchrotron Light Research Institute, Nakhon Ratchasima, 30000, Thailand.
Sci Rep. 2019 Jan 23;9(1):427. doi: 10.1038/s41598-018-36593-9.
Lithium rich layered oxide xLiMnO∙(1-x)LiMO (M = Mn, Co, Ni, etc.) materials are promising cathode materials for next generation lithium ion batteries. However, the understanding of their electrochemical kinetic behaviors is limited. In this work, the phase separation behaviors and electrochemical kinetics of 0.5LiMnO∙0.5LiCoO materials with various LiMnO domain sizes were studied. Despite having similar morphological, crystal and local atomic structures, materials with various LiMnO domain sizes exhibited different phase separation behavior resulting in disparate lithium ion transport kinetics. For the first few cycles, the 0.5LiMnO∙0.5LiCoO material with a small LiMnO domain size had higher lithium ion diffusion coefficients due to shorter diffusion path lengths. However, after extended cycles, the 0.5LiMnO∙0.5LiCoO material with larger LiMnO domain size showed higher lithium ion diffusion coefficients, since the larger LiMnO domain size could retard structural transitions. This leads to fewer structural rearrangements, reduced structural disorders and defects, which allows better lithium ion mobility in the material.
富锂层状氧化物xLiMnO∙(1-x)LiMO（M = Mn、Co、Ni等）材料是下一代锂离子电池很有前景的正极材料。然而，人们对其电化学动力学行为的了解有限。在这项工作中，研究了具有不同LiMnO域尺寸的0.5LiMnO∙0.5LiCoO材料的相分离行为和电化学动力学。尽管具有相似的形态、晶体和局部原子结构，但具有不同LiMnO域尺寸的材料表现出不同的相分离行为，导致锂离子传输动力学不同。在最初的几个循环中，LiMnO域尺寸较小的0.5LiMnO∙0.5LiCoO材料由于扩散路径较短而具有较高的锂离子扩散系数。然而，在长时间循环后，LiMnO域尺寸较大的0.5LiMnO∙0.5LiCoO材料显示出较高的锂离子扩散系数，因为较大的LiMnO域尺寸可以延缓结构转变。这导致结构重排减少、结构无序和缺陷减少，从而使材料中的锂离子迁移性更好。
