Amide-based deep eutectic solvents containing LiFSI and NaFSI salts as superionic electrolytes for supercapacitor...

Area of Science:

• Electrochemistry
• Materials Science
• Green Chemistry

Background:

• Electrochemical double-layer capacitors (EDLCs) are crucial energy storage devices.
• Developing stable and high-performance electrolytes is key to advancing EDLC technology.
• Deep eutectic solvents (DESs) are emerging as promising, environmentally friendly electrolyte alternatives.

Purpose of the Study:

• To synthesize and characterize novel DES-based electrolytes for AC-EDLCs.
• To evaluate the electrochemical properties and performance of these DES electrolytes.
• To explore the potential of DESs as sustainable electrolytes for supercapacitors.

Main Methods:

• Formulation of DES electrolytes using lithium/sodium bis(fluorosulfonyl)imide and N-methylacetamide/formamide.
• Characterization of DES properties: electrochemical window, thermal stability, ionic conductivity, and viscosity.
• Electrochemical performance evaluation of AC-EDLCs using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge.

Main Results:

• DES electrolytes achieved a large electrochemical window (> 2.5 V) and good thermal stability (~150 °C).
• Ionic conductivity ranged from 3-4 mS cm⁻¹, with moderate viscosity (11.3 mPa s).
• AC-EDLCs demonstrated a capacitance of 140 F g⁻¹ with 8% capacity retention over 200 hours.

Conclusions:

• The developed DESs exhibit favorable physicochemical and electrochemical properties for supercapacitor applications.
• These DESs show a superionic character and higher ionicity compared to standard organic electrolytes.
• The study highlights DESs as a promising green-alternative electrolyte for next-generation supercapacitors.