Investigation of Deep Eutectic Solvent Based Super Dielectric Electrolytes for Supercapacitors

Abstract

This study investigates a new type of electrolyte based on deep eutectic solvents. Choline chloride based deep eutectic solvents were prepared and they were used as base ionic solvents for super dielectric theory. Deep eutectic solvent was mixed with a non-conducting material such as fumed silica, alumina. The mixture shows a super dielectric behavior which is used as electrolyte for electrochemical double layer capacitors also known as supercapacitors. The supercapacitor cells were composed of an electrode, a paper-based separator and this super dielectric electrolyte. The electrode of commercial standard supercapacitor is used first as an electrode. Second an electrode slurry was prepared in order to make custom electrode. Then the performance of both cells was investigated. The specific capacitances of cells were measured and the amount of increase at the capacitances was evaluated. The results showed that up to 14-fold increase of the specific capacitances of the commercial supercapacitor have been achieved. Also, up to 12-fold increase of the specific capacitances of our custom-made cells have been achieved. The charge-discharge characteristics and ESR values of the cells confirms that the cells show outperforming properties. Deep eutectic solvents based super dielectric electrolytes are very promising electrolytes for high energy density supercapacitors.