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

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

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.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume158
Issue number9
DOIs
Publication statusPublished - 2011
Externally publishedYes

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Ionic Liquids
storage batteries
Secondary batteries
lithium batteries
Lithium
Ionic liquids
Electrolytes
Cations
Positive ions
electrolytes
cations
liquids
Viscosity
viscosity
gas evolution
cycles
electrochemical oxidation
Electrochemical oxidation
Ionic conductivity
Heavy ions

ASJC Scopus subject areas

  • Electrochemistry
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics

Cite this

Physicochemical properties and application of ionic liquids with N-P bonds as lithium secondary battery electrolytes. / Serizawa, Nobuyuki; Seki, Shiro; Tsuzuki, Seiji; Hayamizu, Kikuko; Umebayashi, Yasuhiro; Takei, Katsuhito; Miyashiro, Hajime.

In: Journal of the Electrochemical Society, Vol. 158, No. 9, 2011.

Research output: Contribution to journalArticle

Serizawa, Nobuyuki ; Seki, Shiro ; Tsuzuki, Seiji ; Hayamizu, Kikuko ; Umebayashi, Yasuhiro ; Takei, Katsuhito ; Miyashiro, Hajime. / Physicochemical properties and application of ionic liquids with N-P bonds as lithium secondary battery electrolytes. In: Journal of the Electrochemical Society. 2011 ; Vol. 158, No. 9.
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