1. College of Materials Science and Engineering, Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124, China;
2. Institute of Solid State Microstructure and Properties, Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China;
3. China Spallation Neutron Source, Dongguan Institute of Neutron Science, Institute of High Energy of Physics, Chinese Academy of Sciences, Dongguan 523803, China
Corresponding author (emails:
The mechanism research of structure-related reactions on Li2MnO3 is important to enhance the electrochemical performance of lithium-manganese-rich layered oxides. Although there are some reports on the structure evolution of Li2MnO3 during cycling process, the employed research techniques are very limited, mainly in/ex-situ X-ray diffraction, X-ray absorption and transmission electron microscopy. Here, atomic pair distribution function, a method to study the local atomic arrangement on the basis of average spectroscopic information, is used for the first time to study the local structure evolution of Li2MnO3 during electrochemical charge/discharge cycles. The results clearly demonstrate that Mn3+/Mn4+ redox couple is activated and Mn ions are reduced during discharging process. Some Mn ions in Mn layers can significantly migrate to Li layers and occupy the octahedral sites. As a result, a portion of inserted Li ions can occupy the face-shared tetrahedron sites, accompanied by the formation of local spinel-like structure. This work provides an important and suitable method based on the average spectroscopic information to investigate the local structure of electrode materials of lithium-ion batteries as well as other advanced battery systems.
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