High Ionic Conductivities of Ionic Materials as Potential Electrolytes

Abstract

Ionic liquids (ILs) are salts consisting of organic cations and inorganic/organic anions having melting transitions lower than 100°C. They hold promise as engineered materials in a variety of modern fields. They are used as green solvents or catalysts for chemical reactions, biocatalysts, biopolymers processing, active pharmaceutical ingradients in medicine, even as electrolytes for batteries. For batteries applications, ionic liquids must have high ionic conductivity, but most of the ionic liquids (monocationic) have low conductivities. To address this limitation, we describe in this chapter dicationic ionic liquids based on extended viologens. The colossal conductivities, σdc ~ 10−1.5·S cm1 of new diatonic ionic liquids in the same range of benchmark materials/electrolytes applied in fuel cells and batteries is reported. The relatively new class of ionic liquids consist of extended viologen bistriflimides containing oligoethyleneoxy groups were prepared via Zincke reaction under mild conditions and are excellent candidates as components in devices for energy conversion and storage applications. The synthesis and ionic conductivities of other ionic liquids and dicationic organic salts will be contrasted with dicationic ionic liquids in this chapter.