Binary ionic liquid electrolytes containing organo-magnesium complex for rechargeable magnesium batteries

• Published in: Journal of power sources 2012-04, Vol.203, p.195-200
• Main Authors: Kakibe, Takeshi, Hishii, Jun-ya, Yoshimoto, Nobuko, Egashira, Minato, Morita, Masayuki
• Format: Article
• Language: English
• Subjects: Anion blending; Applied sciences; Batteries; Cathodic deposition; Coulombic efficiency; Current density; Deposition; Direct energy conversion and energy accumulation; Electric batteries; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolytes; Exact sciences and technology; Ionic liquid; Ionic liquids; Magnesium; Mg battery; Mixing ratios; Voltammetry
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.10.127

► Mixed anion-based ionic liquid was examined for electrolyte of rechargeable Mg battery. ► The anion blending influenced on the ionic structure of the electrolyte containing Mg complex. ► The Mg electrochemistry was improved by the anion blending. ► High coulombic efficiency was achieved for Mg deposition in the mixed anion-based ionic liquid. A binary ionic liquid (IL) system based on a common organic cation, N, N-diethyl- N-methyl- N-(2-methoxyethyl)anmmonium (DEME +), with mixed anion of bis(trifluoromethanesulfonyl)imide (TFSI −) and bis(fluorosulfonyl)imide (FSI −) has been examined as a supporting electrolyte of rechargeable magnesium batteries. Basic properties of the mixed IL were measured as a function of the mixing ratio, n, in the composition of [DEME +][TFSI −] n [FSI −] 1− n . Electrochemical deposition/dissolution behavior of magnesium was investigated in the mixed IL containing an organo-magnesium complex, methyl magnesium bromide with tetrahydrofuran (MeMgBr/THF). Viscosity and ionic conductivity of the mixed IL showed monotonous changes with the mixing ratio, while their thermal properties proved discontinuous changes with the compositions. Coulombic (current) efficiency of 90% or higher was obtained for cathodic deposition of magnesium in the mixed IL containing MeMgBr/THF. The current density for cathodic deposition and anodic dissolution depended on the IL composition, and the maximum value was obtained at the composition of n = 0.5.