Preparation and characterization of new low melting ammonium-based ionic liquids with ether functionality

The Impact of Polymer Electrolyte Properties on Lithium-Ion Batteries

In recent decades, the enhancement of the properties of electrolytes and electrodes resulted in the development of efficient electrochemical energy storage devices. We herein reported the impact of the different polymer electrolytes in terms of physicochemical, thermal, electrical, and mechanical properties of lithium-ion batteries (LIBs). Since LIBs use many groups of electrolytes, such as liquid electrolytes, quasi-solid electrolytes, and solid electrolytes, the efficiency of the full device relies on the type of electrolyte used. A good electrolyte is the one that, when used in Li-ion batteries, exhibits high Li+ diffusion between electrodes, the lowest resistance during cycling at the interfaces, a high capacity of retention, a very good cycle-life, high thermal stability, high specific capacitance, and high energy density. The impact of various polymer electrolytes and their components has been reported in this work, which helps to understand their effect on battery performance. Although, single-electrolyte material cannot be sufficient to fulfill the requirements of a good LIB. This review is aimed to lead toward an appropriate choice of polymer electrolyte for LIBs.

Butyl-Methyl-Pyridinium Tetrafluoroborate Confined in Mesoporous Silica Xerogels: Thermal Behaviour and Matrix-Template Interaction

Organic-inorganic silica composites have been prepared via acid catalyzed sol-gel route using tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) as silica precursors and n-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF₄]) as co-solvent and pore template, by varying the content of the ionic liquid (IL). Morphology of the xerogels prepared using the ionic liquid templating agent were investigated using scanning electron microscopy and small angle neutron scattering (SANS). Thermal analysis has been used in order to evaluate the thermal and structural stability of the materials, in both nitrogen and synthetic air atmosphere. In nitrogen atmosphere, the IL decomposition took place in one step starting above 150 °C and completed in the 150–460 °C temperature interval. In synthetic air atmosphere, the IL decomposition produced two-step mass loss, mainly in the 170–430 °C temperature interval. The decomposition mechanism of the IL inside the silica matrix was studied by mass spectrometric evolved gas analysis (MSEGA). The measurements showed that the degradation of the IL’s longer side chain (butyl) starts at low temperature (above 150 °C) through a C-N bond cleavage, initiated by the nucleophilic attack of a fluorine ion.

Ionic Liquid Electrolytes for Electrochemical Energy Storage Devices

For decades, improvements in electrolytes and electrodes have driven the development of electrochemical energy storage devices. Generally, electrodes and electrolytes should not be developed separately due to the importance of the interaction at their interface. The energy storage ability and safety of energy storage devices are in fact determined by the arrangement of ions and electrons between the electrode and the electrolyte. In this paper, the physicochemical and electrochemical properties of lithium-ion batteries and supercapacitors using ionic liquids (ILs) as an electrolyte are reviewed. Additionally, the energy storage device ILs developed over the last decade are introduced.

Multiple Ether-Functionalized Phosphonium Ionic Liquids as Highly Fluid Electrolytes

Ionic liquids (ILs) are promising electrolytes, although their often high viscosity remains a serious drawback. The latter can be addressed by the introduction of multiple ether functionalization. Based on the highly atom efficient synthesis of tris(2-ethoxyethyl) phosphine, several new phosphonium ionic liquids were prepared, which allows studying the influence of the ether side chains. Their most important physicochemical properties have been determined and will be interpreted using established approaches like ionicity, hole theory, and the Walden plot. There is striking evidence that the properties of phosphonium ionic liquids with the methanesulfonate anion are dominated by aggregation, whereas the two triple ether functionalized ILs with the highest fluidity show almost ideal behavior with other factors being dominant. It is furthermore found that the deviation from ideality is not significantly changed upon introduction of the ether side chains, although a very beneficial impact on the fluidity of ILs is observed. Multiple ether functionalization therefore proves as a powerful tool to overcome the disadvantages of phosphonium ionic liquids with large cations.

Physicochemical properties of functionalized 1,3-dialkylimidazolium ionic liquids based on the bis(fluorosulfonyl)imide anion

A series of functionalized 1,3-dialkylimidazolium ionic liquids based on bis(fluorosulfonyl)imide anion were reported.

New ether-functionalized pyrazolium ionic liquid electrolytes based on the bis(fluorosulfonyl)imide anion for lithium-ion batteries

Li/LiFePO₄ coin cell using a pyrazolium ionic liquid electrolyte based on the FSI anion could exhibit excellent rate properties.

Low-viscosity ether-functionalized pyrazolium ionic liquids based on dicyanamide anions: properties and application as electrolytes for lithium metal batteries

Two ether-functionalized pyrazolium ionic liquids based on dicyanamide anion were used as new electrolytes in Li/LiFePO₄ cells.

Physicochemical Properties of New Dicationic Ether-Functionalized Low Melting Point Ammonium Salts

Eleven new and one previously known but insufficiently characterized dicationic quaternary ammonium (QA) salts were synthesized and characterized. They contain an ethoxy ethyl group either in a side chain and/or as spacer of the diammonium cation and have bromide, hexafluorophosphate (PF6–), bis(trifluoromethanesulfonyl)imide (TFSI), or trifluoromethanesulfonate (TFMS) as an anion. 1H and 13C techniques, mass spectrometry, and elemental analysis together with X-ray diffraction and thermoanalytical methods were used for their characterization both in the liquid and solid state. In addition, residual water content and viscosity measurements were made for the two room temperature ionic liquids (RTILs). Capillary electrophoresis was used to measure the conductivity of the RTILs. Crystal structures of four compounds were determined by X-ray single crystal diffraction, and powder diffraction was used to study the crystallinity of the solid salts and to compare the structural similarities between the single crystals and the microcrystalline bulk form. Two of the TFSI salts were liquids below room temperature, having liquid ranges of ~380 and 350°C, respectively, and seven out of 12 salts melted below 100°C. In addition, both the TFSI and PF6 salts exhibited high thermal stabilities decomposing at about, or above 300°C. Both RTILs presented moderate viscosities at elevated temperatures. The determined physicochemical properties of the reported ILs suggest their applicability for various applications such as heat transfer fluids, high temperature synthesis, and lubricants.