Solvate electrolytes for Li and Na batteries: structures, transport properties, and electrochemistry

Polar solvents dissolve Li and Na salts at high concentrations and are used as electrolyte solutions for batteries. The solvents interact strongly with the alkali metal cations to form complexes in the solution. The activity (concentration) of the uncoordinated solvent decreases as the salt concentration is increased. At extremely high salt concentrations, all the solvent molecules are involved in the coordination of the ions and form the solvates of the salts. In this article, we review the structures, transport properties, and electrochemistry of Li/Na salt solvates. In molten solvates, the activity of the uncoordinated solvent is negligible; this is the main origin of their peculiar characteristics, such as high thermal stability, wide electrochemical window, and unique ion transport. In addition, the solvent activity greatly influences the electrochemical reactions in Li/Na batteries. We highlight the attractive features of molten solvates as promising electrolytes for next-generation batteries.

Glymes as Versatile Solvents for Chemical Reactions and Processes: from the Laboratory to Industry

Glymes, also known as glycol diethers, are saturated non-cyclic polyethers containing no other functional groups. Most glymes are usually less volatile and less toxic than common laboratory organic solvents; in this context, they are more environmentally benign solvents. However, it is also important to point out that some glymes could cause long-term reproductive and developmental damages despite their low acute toxicities. Glymes have both hydrophilic and hydrophobic characters that common organic solvents are lack of. In addition, they are usually thermally and chemically stable, and can even form complexes with ions. Therefore, glymes are found in a broad range of laboratory applications including organic synthesis, electrochemistry, biocatalysis, materials, and Chemical Vapor Deposition (CVD), etc. In addition, glyme are used in numerous industrial applications, such as cleaning products, inks, adhesives and coatings, batteries and electronics, absorption refrigeration and heat pumps, as well as pharmaceutical formulations, etc. However, there is a lack of comprehensive and critical review on this attractive subject. This review aims to accomplish this task by providing an in-depth understanding of glymes' physicochemical properties, toxicity and major applications.

Infrared spectroscopy of ionic liquids: quantitative aspects and determination of optical constants

The infrared (IR) spectra of ionic liquids involving 1-butyl-3-methylimidazolium (BMI) and the (CF(3)SO(2))(2)N(-), BF(4)(-), or PF(6)(-) anions, recorded in the transmission and attenuated total reflection (ATR) modes, exhibit strong differences in the most intense anion absorption profiles. These distortions come from optical effects and make difficult any quantitative analysis of, for example, the antisymmetric stretching vibrations of the BF(4)(-) and PF(6)(-) anions. A method is proposed to determine the optical constants, from which any type of experimental spectrum can be simulated. It is then possible to use the anion vibrational bands as spectroscopic probes of the local interactions occurring in the neat ionic liquids and in solutions. This is illustrated by a direct identification of ion pairs and separated ions in the IR spectra of BMI-PF(6) solutions.