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In our work, the ab-initio methods based on density functional theory (DFT) formalism are used to investigate the effect of nitrogen-rich ionic liquid (EMIMDCA; 1-ethyl-3-methylimidazolium dicyanamide) on the electronic structure of SPE (solid polymer electrolyte) (PEO-LiTFSI) electrolyte with B3LYP method and LANL2DZ basis set. The differences in energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), i.e., energy gap ( E g ) of the PEO, [EMIMDCA], SPE, and ionogel (IG), are found 5.74, 6.59, 3.25, and 2.80 eV, respectively. In SPE, the reduced band gap ( E g ) is due to the transportation of cation of LiTFSI (Li+ ion). Finally, the reduced band gap of IG confirms that IL enhances the transportation of cation of LiTFSI (Li+ ion) through the oxygen atom of PEO. The global and local chemical descriptors and electrochemical stability windows (ESWs) are calculated using the HOMO–LUMO energy levels. Partial charge analysis is studied by Mulliken population analysis and molecular electrostatic potential surface. [ABSTRACT FROM AUTHOR]

In the present study, to accomplish the requirement of an economical endurable quasi-solid-state electrolyte, ionogels have been prepared by nonhydrolytic sol–gel method. Ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, succinonitrile (N≡C–CH2CH2–C≡N), and LiClO4 are incorporated inside the non-conductive matrix of silicon dioxide (SiO2). The structural, vibrational, and thermal properties are studied using experimental techniques. Highly amorphous nature of SM2 and SM4 which contain SCN and SCN with a lithium salt, respectively, in comparison with pure ionogel (SM1) and assisted with lithium salt (SM3) was confirmed by X-ray diffraction and differential scanning calorimetry techniques. The existence of different characteristic peaks in SM1, SM2, SM3, and SM4 ionogels was confirmed by FTIR analysis. The density functional theory was used to study the interaction between the molecules of ionogels. The selectivity and reactivity of the ionogels were investigated using the HOMO–LUMO levels. [ABSTRACT FROM AUTHOR]

In the present study, ionogels have been synthesized by immobilizing IL (1-ethyl-3-methylimidazolium tetrafluoroborate) in silica gel matrices using non-aqueous route. In this process, tetraethyl orho-silane (TEOS) as a precursor to silicon dioxide and formic acid as a solvolytic gelating reagent in reduced molar ratio 1:4 were used. We find that reduced molar concentration of formic acid results the formation of ionogels having less number of closed pores (totally isolated from their neighbours), larger density and stable monolithic form. TEM and SEM measurements are used to visualize the morphology of sample and closed pores present in the sample. N 2 -sorption measurement is used to measure the pore parameters of the silica matrices which shows the mesoporous structure. DSC and TGA results show the change in phase transition temperature and thermal stability of IL upon confinement in silica matrices. Moreover, ionic conductivity of bulk and confined IL is measured using impedance spectroscopy and it has been found that it increases with increasing the temperature as well as concentration of IL in ionogels. Apart from these characterization techniques, ionogels have been characterized using FTIR and fluorescence spectroscopy which exhibit the change in vibrational frequencies and fluorescence behaviour of confined IL. [ABSTRACT FROM AUTHOR]

Highlights: [•] BET surface area of silica gel matrices has increased upon ultrasonic irradiation. [•] Increase in glass transition temperature (T g) of confined ionic liquid (IL). [•] Shift in the vibrational bands of IL confined silica gel matrices. [•] Fluorescence emission of IL shows blue shift upon confinement in silica matrix. [Copyright &y& Elsevier]

Thermophysical properties viz. surfacetension, viscosity, density,and ultrasonic velocity of three ionic liquids 1-butyl-3-methyl imadazoliumoctyl sulfate [BMIM][OcSO4], 1-butyl-3-methyl imadazoliumhexafluorophosphate [BMIM][PF6], and 1-ethyl-3-methyl imadazoliummethanesulfonate [EMIM][MeSO3] have been measured in awide temperature range. Experimental data so obtained have been usedto calculate isentropic compressibility, isothermal expansion coefficient,surface entropy, surface enthalpy, and critical temperature (temperaturewhere the distinction between liquid and gas phase vanishes and thesurface tension tends to zero). Structure–property correlationfor different ILs is also discussed. [ABSTRACT FROM AUTHOR]