A cholesterol based imidazolium ionic liquid crystal: synthesis, characterisation and its dual application as an electrolyte and electrode material

Abstract

A new ionic liquid crystal (ILC) containing cholesterol and bearing a terminal imidazolium moiety was synthesised and its mesophase behaviour was investigated by polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The ILC displayed an intercalated lamellar mesophase having a wide phase range. Cyclic voltammetry studies of the synthesised ILC revealed electrochemical stability with a good electrochemical window. Further, the electrochemical performance of the ILC was evaluated as an electrolyte (0.5% in ethanol) for supercapacitor applications using a three electrode system consisting of a graphene oxide–manganese dioxide (100 μm) coated carbon fiber electrode, silver–silver chloride (Ag–AgCl) reference and platinum foil counter electrodes. Among three different ratios of graphene oxide–manganese dioxide (1 : 1, 1 : 0.5, and 0.5 : 1) investigated, the electrode containing 0.5 : 1 wt% graphene oxide–manganese dioxide over carbon fiber showed good capacitive behaviour with a specific capacitance of 157.5 F g⁻¹ at a constant current density of 0.5 A g⁻¹ along with a good cyclic stability. In addition, the ILC was also studied as an electrode material in combination with carbon paste for investigating electron transfer reactions.