High‐Rate Charging Induced Intermediate Phases and Structural Changes of Layer‐Structured Cathode for Lithium‐Ion Batteries |
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| Authors: | Yong‐Ning Zhou Ji‐Li Yue Enyuan Hu Hong Li Lin Gu Kyung‐Wan Nam Seong‐Min Bak Xiqian Yu Jue Liu Jianming Bai Eric Dooryhee Zheng‐Wen Fu Xiao‐Qing Yang |
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| Institution: | 1. Department of Materials Science, Fudan University, Shanghai, China;2. Department of Chemistry, Brookhaven National Laboratory, Upton, NY, USA;3. Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Department of Chemistry & Laser Chemistry Institute, Fudan University, Shanghai, China;4. Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China;5. Department of Energy and Materials Engineering, Dongguk University‐Seoul, Seoul, Republic of Korea;6. National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA |
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| Abstract: | Using fast time‐resolved in situ X‐ray diffraction, charge‐rate dependent phase transition processes of layer structured cathode material LiNi1/3Mn1/3Co1/3O2 for lithium‐ion batteries are studied. During first charge, intermediate phases emerge at high rates of 10C, 30C, and 60C, but not at low rates of 0.1C and 1C. These intermediate phases can be continuously observed during relaxation after the charging current is switched off. After half‐way charging at high rate, sample studied by scanning transmission electron microscopy shows Li‐rich and Li‐poor phases' coexistence with tetrahedral occupation of Li in Li‐poor phase. The high rate induced overpotential is thought to be the driving force for the formation of this intermediate Li‐poor phase. The in situ quick X‐ray absorption results show that the oxidation of Ni accelerates with increasing charging rate and the Ni4+ state can be reached at the end of charge with 30C rate. These results give new insights in the understanding of the layered cathodes during high‐rate charging. |
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| Keywords: | cathode materials high rate lithium ion batteries structure changes |
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