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Revealing the Origin of Transition-Metal Migration in Layered Sodium-Ion Battery Cathodes: Random Na Extraction and Na-Free Layer Formation |
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| Authors: | Dr Shiyong Chu Prof Duho Kim Gwanghyeon Choi Chunchen Zhang Haoyu Li Prof Wei Kong Pang Yameng Fan Anita M D'Angelo Prof Shaohua Guo Prof Haoshen Zhou |
| Institution: | 1. College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, 210023 China
Shenzhen Research Institute of Nanjing University, Shenzhen, 518000 China These authors contributed equally to this work.;2. Department of Mechanical Engineering (Integrated Engineering Program), Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17104 (Republic of Korea These authors contributed equally to this work.;3. Department of Mechanical Engineering (Integrated Engineering Program), Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17104 (Republic of Korea;4. College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, 210023 China;5. College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing, 210023 China Shenzhen Research Institute of Nanjing University, Shenzhen, 518000 China;6. Institute for Superconducting & Electronic Materials, University of Wollongong, Wollongong, NSW-2522 Australia;7. Australian Synchrotron, Australian Nuclear Science and Technology Organization, 800 Blackburn Road, Clayton, Victoria, 3168 Australia |
| Abstract: | Cation migration often occurs in layered oxide cathodes of lithium-ion batteries due to the similar ion radius of Li and transition metals (TMs). Although Na and TM show a big difference of ion radius, TMs in layered cathodes of sodium-ion batteries (SIBs) can still migrate to Na layer, leading to serious electrochemical degeneration. To elucidate the origin of TM migration in layered SIB cathodes, we choose NaCrO2, a typical layered cathode suffering from serious TM migration, as a model material and find that the TM migration is derived from the random desodiation and subsequent formation of Na-free layer at high charge potential. A Ru/Ti co-doping strategy is developed to address the issue, where the doped active Ru is first oxidized to create a selective desodiation and the doped inactive Ti can function as a pillar to avoid complete desodiation in Ru-contained TM layers, leading to the suppression of the Na-free layer formation and subsequent enhanced electrochemical performance. |
| Keywords: | Layered Sodium-Ion Battery Cathodes Na-Free Layer Random Na Extraction Selective Na Extraction Transition-Metal Migration |