Direct Observation of an Anomalous Spinel‐to‐Layered Phase Transition Mediated by Crystal Water Intercalation |
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Authors: | Dr Sangryun Kim Kwan Woo Nam Dr Soyeon Lee Dr Woosuk Cho Joo‐Seong Kim Byung Gon Kim Prof Yoshifumi Oshima Dr Ju‐Sik Kim Dr Seok‐Gwang Doo Dr Hyuk Chang Prof Doron Aurbach Prof Jang Wook Choi |
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Institution: | 1. Graduated School of EEWS and KAIST Institute NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305‐701 (Korea);2. Department of Electronic Chemistry, Tokyo Institute of Technology, 4259 G1‐1 Nagatsuta, Midori‐ku, Yokohama 226‐8502 (Japan);3. Advanced Batteries Research Center, Korea Electronics Technology Institute (KETI), 25 Saenari‐ro, Bundang‐gu, Seongnam 463‐816 (Republic of Korea);4. School of Materials Science I, Japan Advanced Institute of Science and Technology, 1‐1?m1‐61 Asahidai, Nomi, Ishikawa 923‐1292 (Japan);5. Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., LTD, 130 Samsung‐ro, Yeongtong‐gu, Suwon‐si, Gyeonggi‐do 443‐803 (Republic of Korea);6. Department of Chemistry and Bar‐Ilan Institute of Nanotechnology and Advanced Materials, Bar‐Ilan University, Ramat‐Gan 5290002 (Israel) |
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Abstract: | The phase transition of layered manganese oxides to spinel phases is a well‐known phenomenon in rechargeable batteries and is the main origin of the capacity fading in these materials. This spontaneous phase transition is associated with the intrinsic properties of manganese, such as its size, preferred crystal positions, and reaction characteristics, and it is therefore very difficult to avoid. The introduction of crystal water by an electrochemical process enables the inverse phase transition from spinel to a layered Birnessite structure. Scanning transmission electron microscopy can be used to directly visualize the rearrangement of lattice atoms, the simultaneous insertion of crystal water, the formation of a transient structure at the phase boundary, and layer‐by‐layer progression of the phase transition from the edge. This research indicates that crystal water intercalation can reverse phase transformation with thermodynamically favored directionality. |
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Keywords: | Birnessite crystal water layered cathode materials phase transitions spinels |
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