Binary ionic liquids hybrid electrolyte based supercapacitors with high energy & power density

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Supercapacitors require high energy and power densities for practical use.
• Ionic liquids (ILs) offer electrochemical stability but suffer from high viscosity and low conductivity, limiting supercapacitor performance.
• Existing organic electrolytes in supercapacitors have limitations in working voltage.

Purpose of the Study:

• To develop a novel binary ionic liquids (BILs) hybrid electrolyte to overcome the limitations of traditional ILs.
• To improve the ionic conductivity and reduce the viscosity of IL electrolytes for enhanced supercapacitor performance.
• To achieve higher energy and power densities in supercapacitors compared to existing commercial options.

Main Methods:

• Formulation of a binary ionic liquids (BILs) electrolyte by mixing trimethyl propylammonium bis(trifluoromethanesulfonyl)imide ([TMPA][TFSI]) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([Pyr14][TFSI]) in acetonitrile.
• Characterization of the BILs electrolyte's conductivity, viscosity, and electrochemical stability window.
• Assembly and testing of supercapacitors using activated carbon electrodes and the developed BILs electrolyte.

Main Results:

• The prepared BILs electrolyte exhibited superior electric conductivity (44.3 mS cm⁻¹) and low viscosity (0.692 mPa s).
• The electrolyte demonstrated a wide electrochemical stability window of 4.82 V.
• Supercapacitors achieved a high working voltage of 3.1 V, with a maximum energy density of 28.3 Wh kg⁻¹ and power density of 32.16 kW kg⁻¹.

Conclusions:

• The novel BILs hybrid electrolyte significantly enhances supercapacitor performance, offering superior energy and power densities.
• This advanced electrolyte system surpasses the performance of commercial supercapacitors based on conventional organic electrolytes.
• The findings pave the way for next-generation supercapacitors with improved efficiency and rate capabilities.