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ID 54566
フルテキストURL
著者
Morita, Ryohei Graduate School of Natural Science & Technology, Okayama University
後藤 和馬 岡山大学大学院自然科学研究科
Fukunishi, Mika Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University
Kubota, Kei Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University
Komaba, Shinichi Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University
Nishimura, Naoto Department of Chemistry and Materials Technology, Kyoto Institute of Technology
Yumura, Takashi Department of Chemistry and Materials Technology, Kyoto Institute of Technology
Deguchi, Kenzo National Institute for Materials Science
Ohki, Shinobu National Institute for Materials Science
Shimizue, Tadashi National Institute for Materials Science
石田 祐之 岡山大学大学院自然科学研究科
抄録
We examined the state of sodium electrochemically inserted in HC prepared at 700–2000 °C using solid state Na magic angle spinning (MAS) NMR and multiple quantum (MQ) MAS NMR. The 23Na MAS NMR spectra of Na-inserted HC samples showed signals only in the range between +30 and −60 ppm. Each observed spectrum was ascribed to combinations of Na+ ions from the electrolyte, reversible ionic Na components, irreversible Na components assigned to solid electrolyte interphase (SEI) or non-extractable sodium ions in HC, and decomposed Na compounds such as Na2CO3. No quasi-metallic sodium component was observed to be dissimilar to the case of Li inserted in HC. MQMAS NMR implies that heat treatment of HC higher than 1600 °C decreases defect sites in the carbon structure. To elucidate the difference in cluster formation between Na and Li in HC, the condensation mechanism and stability of Na and Li atoms on a carbon layer were also studied using DFT calculation. Na3 triangle clusters standing perpendicular to the carbon surface were obtained as a stable structure of Na, whereas Li2 linear and Li4 square clusters, all with Li atoms being attached directly to the surface, were estimated by optimization. Models of Na and Li storage in HC, based on the calculated cluster structures were proposed, which elucidate why the adequate heat treatment temperature of HC for high-capacity sodium storage is higher than the temperature for lithium storage.
備考
This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. https://creativecommons.org/licenses/by-nc/3.0/
発行日
2016-07-25
出版物タイトル
Journal of Materials Chemistry A
4巻
34号
出版者
ROYAL SOC CHEMISTRY
開始ページ
13183
終了ページ
13193
ISSN
2050-7488
NCID
AA12603290
資料タイプ
学術雑誌論文
言語
English
著作権者
© Authors
論文のバージョン
publisher
DOI
Web of Sience KeyUT