Interfacial Preferential Adsorption and Molecular Mobility Restriction Enabling 3.2 V High Voltage Supercapacitor

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Commercial supercapacitors have limited energy storage due to narrow voltage windows.
• Electrolyte decomposition, particularly of acetonitrile (AN), at electrode interfaces causes performance degradation.

Purpose of the Study:

• To enhance the electrochemical stability of AN-based electrolytes for supercapacitors.
• To suppress side reactions and improve the voltage window and cycling performance.

Main Methods:

• Introduction of ethylene carbonate (EC) into AN-based electrolytes.
• Theoretical calculations and experimental characterizations (e.g., electrochemical testing).
• Analysis of EC's adsorption and AN diffusion suppression mechanisms.

Main Results:

• The AN-EC electrolyte achieved a 3.2 V voltage window.
• Demonstrated enhanced cycling stability with 70% capacity retention after 30,000 cycles.
• Achieved superior energy and power densities (33.3 Wh kg⁻¹ at 749 W kg⁻¹ and 17.6 Wh kg⁻¹ at 9,883 W kg⁻¹).

Conclusions:

• EC addition effectively suppresses AN interfacial decomposition through preferential adsorption and reduced diffusion.
• The developed AN-EC electrolyte offers a promising strategy for high-performance supercapacitors.
• Provides a framework for designing stable electrolytes for advanced electrochemical energy storage.