総説・解説等

The development of suitable separation technologies for the separation of carbon dioxide is a pressing technological requirement. The application of ion gel membranes for this purpose continues to stimulate a great deal of research, and in this study we focus on the chemical structure of the ionic liquid component in the ion gel, and its interactions with the sulfonated polyimide polymer. Whilst such membranes are known to give promising carbon dioxide separation properties together with mechanical strength and thin-film-processability, we further elaborate on how changing the cation of the ionic liquid from a typical imidazolium cation to a protic variant effects the physicochemical, thermal, and structural properties of the membranes, and how these changes further influence the carbon dioxide separation properties. We compare and contrast our findings with our earlier study on protic and aprotic ammonium-based ionic liquids, and highlight that for CO

Certain concentrated mixtures of lithium salt and solvent ( ligand) are no longer simple solutions, but categorized as solvate ionic liquids (SILs), where the solvent strongly coordinates to the cation to form a solvate, a negligible amount of free solvent remains, and thus the SIL consists of the solvate cation and the anion. Typical examples are mixtures of lithium bis(trifluoromethane sulfonyl) amide (Li[TFSA]) and certain glymes (CH3-O-(CH2-CH2-O)(n)-CH3) The successful formation of a SIL greatly depends on both the ligand and lithium salt structures. To obtain robust and long-lived solvates, a ligand exhibiting a chelate effect is essential and n = 3 and 4 (i.e. triglyme and tetraglyme) are suitable for the formation of lithium solvates. The Lewis basicity of the lithium salt anion also significantly affects the formation of SILs. Specifically, a weak Lewis basicity promotes the formation of a SIL, since the ligand-Li+ interaction overwhelms the Li+-anion interaction. SILs can be diluted with rather low polarity solvents to increase the ionic conductivity, where the solvate structure is maintained even after the dilution. SILs exhibit unique features as electrolytes, including the enhancement of oxidation stability of the component glymes, unique Li+ transport through ligand exchange when interfacial electrochemical reactions are occurring, the inhibition of aluminum corrosion when Al foil is used as a cathode current collector, poorly-solubilizing towards ionic electroactive materials, and electrochemical graphite intercalation reactions. These features greatly enhance the possibility for application of SILs as next generation lithium battery electrolytes. Furthermore, new polymer electrolytes containing SILs have been proposed, simultaneously enabling film-processability, high ionic conductivity, thermal stability, and a wide potential window. Preservation of the solvate structure in the polymeric phases is pivotal to such achievements.

International audience

The growing global demand for energy has led to the active development of efficient energy generation and storage technologies, driving the development of electrochemical devices such as high-energy density rechargeable batteries, fuel cells and solar cells. One of the essential materials for the development of high-performance electrochemical devices is the electrolyte. Currently, flammable electrolyte solutions are used, causing problems such as leakage and ignition incidents. It would be significant if the electrolyte could be replaced with a solid electrolyte, as this would eliminate these problems. In addition, with the increasing size of electrochemical devices, there is a societal demand for safer electrochemical devices, and the development of high-performance solid electrolytes is becoming more active. Although development has mainly focused on inorganic and solid polymer electrolytes, organic ionic plastic crystals (OIPCs) are beginning to attract attention as new candidates for flexible solid electrolytes. In this review, we describe OIPCs for lithium secondary batteries. Firstly, we introduce OIPCs and OIPC/polymer composites as lithium-ion conductors and discuss the effects of ionic architecture and polymer species on their ionic conduction. Secondly, we present recent progress in the development of lithium secondary batteries with OIPC-based solid electrolytes.

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 become unique (i.e., not easily achieved by other materials) must be explored. Thus, through strong demands for research and consideration of ILs unique properties, we will be able to identify indispensable applications for ILs.