Bis-quaternary ammonium cation-based organic ionic plastic crystals: plastic crystal behaviour and ionic liquid properties above melting points

A new family of organic ionic plastic crystals (OIPCs) based on bis-quaternary ammonium cations was synthesized and characterized. The synthesized bis-quaternary ammonium salts with bis(trifluoromethanesulfonyl) imide (TFSI−) anions exhibit plastic crystal properties as determined by differential scanning calorimetry (DSC). The high ionic conductivity of the compounds in the solid-state indicated that this new family of OIPCs can be promising solid-state electrolytes for electrochemical devices. Cyclic voltammetry characterization of OIPCs in the liquid-state revealed their wide electrochemical windows and highly reversible lithium metal electrodeposition properties.