Solvent-Free Electrolytes for Electrical Double Layer Capacitors

A mechanically-stable non-aqueous inorganic gel polymer electrolyte that is based on association of sol-gel agents and Ionic Liquid is considered here for application in solid-state solvent free supercapacitors. The first part is devoted to the electrochemical characterization of the ionogel bulk properties. In the second part, an electrochemical cell using activated carbon as active materials and the new ionogel electrolyte has been characterized over a wide temperature range using cyclic voltammetry and electrochemical impedance spectroscopy. The use of high IL content (70%) has led to an increase of both the operating voltage window (up to 3 V) and the electrolyte ionic conductivity (around 4.7 mS/cm). The resulting double layer capacitance of the microporous activated carbon device was found to be as high as 80 F/g; even more important, this quasi solid electrolyte works well over a wide temperature range (namely, from −30 to more than 80°C).