Physicochemical properties and application of ionic liquids with N-P bonds as lithium secondary battery electrolytes

Nobuyuki Serizawa, Shiro Seki, Seiji Tsuzuki, Kikuko Hayamizu, Yasuhiro Umebayashi, Katsuhito Takei, Hajime Miyashiro

研究成果: Article査読

6 被引用数 (Scopus)


Physicochemical properties such as density, viscosity, ionic conductivity, and self-diffusion coefficient of two types of room-temperatureionic liquids composed of cations with N-P bonds were investigated. One is an ionic liquid composed of cations with N-P-O bond, namely, tri(N,N-dimethylamino)-n- butoxyphosphonium bis(trifluoromethanesulfonyl)amide (TABP-TFSA) and has a relatively low viscosity (38 mPa s at 30C) due to the high internal mobility of the cation, despite its large ion size. TABP-TFSA showed a characteristic electrochemical oxidation behavior, such as a wide electrochemical potential window of stability without gas evolution. Formation of passivation film on a Pt electrode was suggested from the results of potential sweep experiments. The lithium secondary battery ([LiCoO2Li] cell) using TABP-TFSA as the electrolyte achieved stable charge-discharge operations in over 500 cycles. For another ionic liquid with N-P bond, namely, TAEP-TFSA (TAEP+ tri(N-methyl-N-(n-butylamino))ethylphosphonium), less battery cycle stability and low rate performances were observed, despite the higher ionic dissociation than TABP-TFSA, probably because of the high viscosity and low electrochemical oxidative stability. It is shown that the introduction of oxygen in the cation like N-P-O produces better performances compared with the cation having N-P structure.

ジャーナルJournal of the Electrochemical Society
出版ステータスPublished - 2011

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 再生可能エネルギー、持続可能性、環境
  • 表面、皮膜および薄膜
  • 電気化学
  • 材料化学


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