title: In situ SEM observation of the Si negative electrode reaction in an ionic-liquid-based lithium-ion secondary battery.
abstract: By exploiting characteristics such as negligible vapour pressure and ion-conductive nature of an ionic liquid (IL), we established an in situ scanning electron microscope (SEM) method to observe the electrode reaction in the IL-based Li-ion secondary battery (LIB). When 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide ([C2mim][FSA]) with lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) was used as the electrolyte, the Si negative electrode exhibited a clear morphology change during the charge process, without any solid electrolyte interphase (SEI) layer formation, while in the discharge process, the appearance was slightly changed, suggesting that a morphology change is irreversible in the charge-discharge process. On the other hand, the use of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][TFSA]) with Li[TFSA] did not induce a change in the Si negative electrode. It is interesting to note this distinct contrast, which could be attributed to SEI layer formation from the electrochemical breakdown of [C2mim](+) at the Si negative electrode|separator interface in the [C2mim][TFSA]-based LIB. This in situ SEM observation technique could reveal the effect of the IL species electron-microscopically on the Si negative electrode reaction.
authors: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan ttsuda@chem.eng.osaka-u.ac.jp kuwabata@chem.eng.osaka-u.ac.jp.
authors: Tetsuya
authors: T
authors: Tsuda
authors: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors: Tsukasa
authors: T
authors: Kanetsuku
authors: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors: Teruki
authors: T
authors: Sano
authors: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
authors: Yoshifumi
authors: Y
authors: Oshima
authors: Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan.
authors: Koichi
authors: K
authors: Ui
authors: Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680, Japan.
authors: Masaki
authors: M
authors: Yamagata
authors: Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680, Japan.
authors: Masashi
authors: M
authors: Ishikawa
authors: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan ttsuda@chem.eng.osaka-u.ac.jp kuwabata@chem.eng.osaka-u.ac.jp.
authors: Susumu
authors: S
authors: Kuwabata
keywords: in situ SEM observation; ionic liquid; lithium-ion battery; negative electrode; scanning electron microscope; silicon