Observation of partial reduction of manganese in the lithium rich layered oxides, 0.4Li2MnO3–0.6LiNi1/3Co1/3Mn1/3O2, during the first charge
| العنوان: | Observation of partial reduction of manganese in the lithium rich layered oxides, 0.4Li2MnO3–0.6LiNi1/3Co1/3Mn1/3O2, during the first charge |
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| المؤلفون: | Hyung Cheoul Shim, Donghan Kim, Dong-Wook Shin, Chang Su Woo, Seungmin Hyun, Taehwan Yu, Jae-Pyoung Ahn |
| المصدر: | Physical Chemistry Chemical Physics. 19:1268-1275 |
| بيانات النشر: | Royal Society of Chemistry (RSC), 2017. |
| سنة النشر: | 2017 |
| مصطلحات موضوعية: | X-ray absorption spectroscopy, Materials science, Valence (chemistry), Absorption spectroscopy, Electron energy loss spectroscopy, Inorganic chemistry, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Manganese, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Oxygen, 0104 chemical sciences, Ion, chemistry, Scanning transmission electron microscopy, Physical and Theoretical Chemistry, 0210 nano-technology |
| الوصف: | Lithium-rich layered oxides show promise as high-energy harvesting materials due to their large capacities. However, questions remain regarding the large irreversible loss in capacities for the first charge-discharge cycle due to oxygen removal in lattices related to layered Li2MnO3. Herein we present detailed studies on Li-rich Mn-based layered oxides of 0.4Li2MnO3-0.6LiNi1/3Co1/3Mn1/3O2 (Li-rich NCM) electrochemically activated between 2.5 V and 4.3 or 4.7 V vs. Li+/Li. Electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) revealed unusual manganese reduction after the first charge up to a high voltage of 4.7 V. Moreover, the electronic structure did not fully recover to the original pristine of Mn4+ state after discharge. Interestingly, these phenomena were not limited to a single particle, but were observed across the entire electrode. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images and electron dispersive spectra (EDS) also showed a dramatic decline in oxygen content with highly porous morphologies, associated with oxygen vacancy formation following oxidation of O2- ions to O2. Our analysis suggests that an unstable manganese valence state with severe defects due to oxygen vacancies may lead to large irreversible capacity loss during the first charge-discharge cycle of Li-rich layered oxides. |
| تدمد: | 1463-9084 1463-9076 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::fe9514eb991a1c8397b85519536c4147 https://doi.org/10.1039/c6cp07574f |
| رقم الأكسشن: | edsair.doi...........fe9514eb991a1c8397b85519536c4147 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14639084 14639076 |
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