Comparison of the ionic conductivity of pure imidazolium nitrate and that doped with a lithium nitrate salt in liquid and gel forms as potential electrolytes

Este artigo pertence ás actas do The 23rd International Electronic Conference on Synthetic Organic Chemistry.[Abstract] Current electrolytes for electrochemical energy storage devices are made of solvents, which often present problems of flammability, corrosion and high toxicity. Ionic liquids and mixtures with metal salts are proposed as a good selection for safer electrolytes due to their properties such as, among others, non-flammability, negligible vapor pressure, high ionic conductivity and wide electrochemical window. In this work, the electrical conductivity of solutions of the ionic liquid 1-ethyl-3-methylimidazolium nitrate ([EIm][NO3]) with lithium nitrate salt in three different concentrations is analyzed for liquid and gel states. The temperature and salt concentration dependences of electrical conductivity are studied for liquid and gel states. As expected, an increase in conductivity with temperature and a decrease with salt concentration were observed, except for the case of gel [EIm][NO3] with a salt concentration of 0.5 m, which shows a small increase in conductivity compared to the pure gel. Comparison of the conductivity of the liquid and gel states shows a significant increase for the gel state at low concentrations of the added salt.Ministerio de Economía y Competitividad; MAT2017-89239-C2-1-PXunta de Galicia; ED431C 2016/001Xunta de Galicia; ED431D 2017/0

Electrical Conductivity and Nyquist Plot of C₄C₁Im BF₄ at Room Temperature by Impedance Spectroscopy

[Abstract] Ionic liquids (ILs) represent a real alternative for electrochemical applications due to their remarkable characteristics, namely a very low vapour pressure, low flammability, high thermal stability, wide potential window and high ionic conductivity. In this work, Nyquist plot and impedance spectroscopy at room temperature is proposed as an alternative method to obtain the ionic conductivity for ionic liquids by using an Agilent HP 4284A RLC precision meter. For this propose, the IL 1-butyl-3-methylimidazolium tetrafluoroborate (C₄C₁Im BF₄) was selected and results were compared with the previously obtained from the conductimeter CRISON GLP31.This work was supported by Spanish Ministry of Economy and Competitiveness and FEDER Program through the project MAT2017-89239-C2-1-P and by Xunta de Galicia through GRC ED431C 2020/10 project and the Galician Network of Ionic Liquids (ReGaLIs) ED431D 2017/06. P. Vallet and J. J. Parajó thank funding support of FPI Program from Spanish Ministry of Science, Education and Universities and I2C postdoctoral Program of Xunta de Galicia, respectivelyXunta de Galicia; ED431C 2020/10Xunta de Galicia; ED431D 2017/0

Structural Characterization by NMR Procedure of C₄C₁Pyrr TFSI Doped with Lithium TFSI Salt in Liquid and Gel States

[Abstract] Ionic liquids represent a viable option as electrolytes for electrochemical applications such as energy storage devices, due to their high ionic conductivity and wide electrochemical window. However, liquid electrolytes present important problems of safety and performance, and encapsulation in a solid matrix can be a good solution to improve it. In this work, changes in the structure of the mixtures of ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide against the concentration of the salt (0, 0.1, and 1.5 molal), and the effect of nanoconfinement through gelation process were studied using NMR technique.This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER Program through the projects MAT2014-57943-C3-1-P, MAT2014-57943-C3-3-P, MAT2017-89239-C2-1-P as well as by Xunta de Galicia through GRC ED431C 2020/10 project and the Galician Network of Ionic Liquids (ReGaLIs) ED431D 2017/06. P. Vallet and J. J. Parajó thank funding support of FPI Program from the Spanish Ministry of Science, Education and Universities and I2C postdoctoral Program of Xunta de Galicia, respectivelyXunta de Galicia; ED431C 2020/10Xunta de Galicia; ED431D 2017/0

Thermophysical Characterization of Two DyethylMethylAmmonium Ionic Liquids

Density (ρ), speed of sound (U), and the derived magnitudes of two diethylmethylammoniumionic liquids (ILs) against temperature have been studied in this work. The chosen ILs were diethylmethylammonium trifluoromethanesulfonate [C2C2C1N][OTf] and diethylmethylammonium methanesulfonate [C2C2C1N][MeSO3]. In order to analyze the influence of water content, saturated and dried samples of these ILs were studied. The ILs were dried using a vacuum pump, and the saturation level (28% and 6% in weight for [C2C2C1N][MeSO3] and [C2C2C1N][OTf], respectively) was achieved by keeping the ILs in an open bottle at ambient temperature. Direct measurements of density and speed of sound were taken with an Anton Paar DSA 5000. Linear equations were used to express the correlation of both properties with temperature, and the thermal expansion coefficient, αp, and the adiabatic bulk modulus constant, KS, have been also obtained. Additionally, results were compared with previous literature data in order to have a deeper understanding of the liquid properties and detect possible anomalous behaviors. The effect of water content is different on both properties. Thus, the density of the samples slightly increases when water is removed, whereas the opposite behavior was found with regard to the speed of sound, which decreased when the water content was completely removed