Redox-Driven Route for Widening Voltage Window in Asymmetric Supercapacitor

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous asymmetric supercapacitors offer high energy density and safety.
• Their performance is limited by water's narrow electrochemical stability window.
• Expanding the operating voltage is crucial for improved energy storage.

Purpose of the Study:

• To demonstrate a kinetic approach for widening the voltage window of aqueous asymmetric supercapacitors.
• To utilize in situ activated Mn3O4 and VO2 electrodes for enhanced performance.
• To investigate the underlying redox mechanisms responsible for the expanded voltage window.

Main Methods:

• Fabrication of asymmetric supercapacitors using in situ activated Mn3O4 and VO2 electrodes.
• Electrochemical characterization to determine operating voltage and stability.
• Analysis of redox reactions at electrode-electrolyte interfaces to understand mechanism.

Main Results:

• Achieved a working voltage of 2.2 V in an aqueous asymmetric supercapacitor.
• Demonstrated high energy density of 42.7 Wh/kg and power density of ~1.1 kW/kg.
• Identified specific redox potentials for Mn and V species that suppress water splitting.

Conclusions:

• The kinetic approach effectively expands the voltage window of aqueous supercapacitors.
• Activated Mn3O4 and VO2 electrodes enable higher energy and power densities.
• This strategy offers a pathway for developing safer, high-performance aqueous energy storage devices.