Structure and nanostructure in ionic liquids.

Ionic liquids (ILs) are liquids consisting entirely of ions and can be further defined as molten salts having melting points lower than 100 °C. One of the most important research areas for IL utilization is undoubtedly their energy application, especially for energy storage and conversion materials and devices, because there is a continuously increasing demand for clean and sustainable energy. In this article, various application of ILs are reviewed by focusing on their use as electrolyte materials for Li/Na ion batteries, Li-sulfur batteries, Li-oxygen batteries, and nonhumidified fuel cells and as carbon precursors for electrode catalysts of fuel cells and electrode materials for batteries and supercapacitors. Due to their characteristic properties such as nonvolatility, high thermal stability, and high ionic conductivity, ILs appear to meet the rigorous demands/criteria of these various applications. However, for further development, specific applications for which these characteristic properties becom...

Application of Ionic Liquids to Energy Storage and Conversion Materials and Devices

Ionic liquids (ILs) including ambient-temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because ILs were considered as highly moisture-sensitive solvents that should be handled in a glove box. After the first synthesis of moisture-stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid-like properties, e.g., some ILs enable dissolution of insoluble bio-related materials and the use as tailor-made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi-solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid-vacuum technologies, such as X-ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials.

New frontiers in materials science opened by ionic liquids.

We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

Frontiers in poly(ionic liquid)s: syntheses and applications

The thermal and physicochemical properties of protic ionic liquids (PILs) are reported. It is highly evident that there has been an extensive range of alkylammonium, imidazolium, and heterocyclic cations paired with many organic and inorganic anions that have been employed to prepare PILs. There has been strong interest in modifying the properties of PILs through the addition of water or other molecular solvents. For many applications, the presence of some water in the PILs is not detrimental, and instead leads to enhanced solvent properties such as lower viscosity, higher conductivities, and lower melting points. It remains an issue of definition though of how to refer to these resulting protic solutions. There is also an ongoing difficulty surrounding how to describe the proton activity in the PILs, analogous to pH in aqueous systems. For a broad range of applications, it has been reported that the acidity/basicity of the PIL or PIL-solvent system is crucial for their beneficial properties. It is expected that the fundamental properties of PILs will continue to be explored, along with continued interest in many existing and new applications, such as in electrochemistry, organic and inorganic synthesis, and biological applications. In particular, there has been a significant interest in a broad- range of PILs for use as electrolytes and incorporation in polymer electrolytes for fuel cells, and other energy storage devices.

Protic Ionic Liquids: Evolving Structure–Property Relationships and Expanding Applications

A magnetic ionic liquid, which shows a strong response to magnetic field, has been discovered. We synthesized an ionic liquid by mixing 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and FeCl3, in...

Discovery of a magnetic ionic liquid [bmim]FeCl4

A novel protic ionic liquid and ionic melts consisting of a Bronsted acid and base were prepared with the combination of bis(trifluoromethanesulfonyl)imide (HTFSI) and benzimidazole (BIm) at various molar ratios. The thermal properties, ionic conductivities, 1H-NMR chemical shifts, Raman spectra, 1H and 19F self-diffusion coefficients, and electrochemical polarization curves were explored. A mixture at the equivalent molar ratio formed a protic neutral salt, and its thermal stability was higher than 350 °C. The phase diagram of the BIm−HTFSI binary mixtures revealed that stoichiometric complexes other than the neutral salt were found at [BIm]/[HTFSI] = 2/1 and 6/1. In these BIm excess compositions, fast proton exchange reactions between protonated BIm (HBIm+) and free BIm were observed at 140 °C, where BIm and HBIm+ were indistinguishable by 1H-NMR but were distinguishable by Raman spectroscopy. The proton transfer became faster and also the proton transference number increased with increasing BIm mole fr...

Proton-Conducting Properties of a Brønsted Acid−Base Ionic Liquid and Ionic Melts Consisting of Bis(trifluoromethanesulfonyl)imide and Benzimidazole for Fuel Cell Electrolytes

Satoshi Hayashi

Papers

Discovery of a magnetic ionic liquid [bmim]FeCl4

Proton-Conducting Properties of a Brønsted Acid−Base Ionic Liquid and Ionic Melts Consisting of Bis(trifluoromethanesulfonyl)imide and Benzimidazole for Fuel Cell Electrolytes

Discovery of a Magnetic Ionic Liquid [bmim]FeCl4.