I&EC 118 |
| Ionic liquids (IL) possess unique properties that make them ideal battery electrolyte. As a result, ionic conductivity, dynamic viscosity, and electrochemical and thermal stability of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) with or without lithium tetrafluoroborate (LiBF4) were studied. Thermogravimetric investigations showed that the ionic solutions are completely damaged above 450°C. Besides, original differential scanning calorimetric results were obtained, and allowed the observation of characteristic temperatures. Temperature and concentration in LiBF4 dependences of ionic conductivity and dynamic viscosity were analyzed thanks to impedance spectroscopy and rheometric methods, respectively. It was demonstrated that viscosity decreases with temperature, whereas specific conductivity increases. In the -10°C to 60°C temperature range, the conductivities values varied from 0.07 mS/cm to 10 mS/cm, while the viscosities values are bounded between 0.02 Pa.s and 3.9 Pa.s. Furthermore, fitting laws are proposed to describe the thermal behaviors. On the other hand, it was shown that an increase in ionic conductivity and a decrease in dynamic viscosity are expected when LiBF4 concentration increases. Cyclic voltammetry experiments indicated that the reduction of BMI+ on an iron working electrode occurred at 0.94 V vs. a Li/Li+ reference electrode, whereas BF4- was oxidized on a platinum working electrode at 5.67 V vs. a Li/Li+. Then LiCoO2/Li4Ti5O12 and LiFePO4/Li4Ti5O12 batteries using BMIBF4-LiBF4 in various concentrations as the electrolyte were assembled for cycling tests. |
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Ionic Liquids: Not Just Solvents Anymore OR Ionic Liquids: Parallel Futures (Sponsored by Green Chemistry and Engineering, Separation Science and Technology and Novel Chemistry with Industrial Applications Sub-Divisions)
8:00 PM-10:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster
Division of Industrial and Engineering Chemistry |