Performance of ethanolamine-based ionic liquids as novel green electrolytes for the electrochemical energy storage applications

Abstract

Supercapacitors are promising technologies for extremely effective energy storage and power management, which is a critical and major area of worldwide technological advancement. Ionic liquids (ILs) are an environmentally benign promising emerging class of versatile solvent systems. In this paper, for the first time, a new approach to the application of monoethanolamine-based ILs with anions formate, acetate, and propionate ([HEA]F, [HEA]A, and [HEA]P) as eco-friendly, affordable, and easy synthesis electrolytes are proposed for activated carbon (AC)-based supercapacitors. The ionic conductivity and the electrochemical stable potential window (ESPW) of ionic liquids were assessed. The electrochemical performance of synthesized ILs as an electrolyte in AC-based supercapacitors was compared. Electrochemical properties were performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and galvanostatic charge-discharge (GCD) methods to evaluate the electrolytic performance of ionic liquids in supercapacitors. The charge transfer resistance (Rct) and solution resistance (Rs) decreased with decreasing anion size of ILs. At a scan rate of 10 mVs−1, the prepared supercapacitors using [HEA]F, [HEA]A, and [HEA]P ionic liquids deliver specific capacitance of 114, 95, and 73 F g−1, respectively. The maximum power density 2941 W kg−1 and maximum energy density 70 Wh kg−1 were obtained for the prepared supercapacitor using [HEA]F ionic liquid. The supercapacitors prepared with [HEA]F, [HEA]A and [HEA]P electrolytes show capacitance retention of 96%, 91% and 87% after 5000 charge-discharge cycles, respectively.