Stability of Ionic Liquids against Sodium Metal: A Comparative Study of 1-Ethyl-3-methylimidazolium Ionic Liquids with Bis(fluorosulfonyl)amide and Bis(trifluoromethylsulfonyl)amide

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• 作者：Takafumi Hosokawa ; Kazuhiko Matsumoto ; Toshiyuki Nohira ; Rika Hagiwara ; Atsushi Fukunaga ; Shoichiro Sakai ; Koji Nitta
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 12, 2016
• 年：2016
• 卷：120
• 期：18
• 页码：9628-9636
• 全文大小：611K
• 年卷期：0
• ISSN：1932-7455

文摘

The stability of [C₂C₁im][FSA] (C₂C₁im⁺: 1-ethyl-3-methylimidazolium; FSA^–: bis(fluorosulfonyl)amide) and [C₂C₁im][TFSA] (TFSA^–: bis(trifluoromethylsulfonyl)amide) ionic liquids against Na metal has been investigated in view of their application as electrolytes for Na secondary batteries. Cyclic voltammetry revealed that Na metal electrodeposition/dissolution reactions occur in Na[FSA]–[C₂C₁im][FSA], whereas these processes do not occur in Na[TFSA]–[C₂C₁im][TFSA]. Both visual and spectroscopic changes were observed for Na[TFSA]–[C₂C₁im][TFSA] after immersion of Na metal for 4 weeks, but no changes were observed for Na[FSA]–[C₂C₁im][FSA]. X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy indicated that there were differences in the thickness of the surface films on Na metal immersed in these ionic liquids. The presence of Na⁺ also affects the thickness of the surface film, and the nature of the surface films determines the difference in the stability of Na metal in these two ionic liquids.