Advanced aqueous phenazine redox flow battery enhanced by selective interfacial water behavior on Co/NC modified...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous organic redox flow batteries (RFBs) are promising for energy storage.
• Traditional porous carbon electrodes exhibit limited redox reaction kinetics for organic electrolytes like phenazine derivatives.
• Low electrochemical activity hinders the efficiency of phenazine-based RFBs.

Purpose of the Study:

• To develop an electrocatalyst that enhances the redox reaction kinetics of phenazine derivatives in aqueous organic RFBs.
• To investigate the synergistic effects in composite electrocatalysts for improved battery performance.
• To elucidate the reaction mechanism of organic electroactive species on catalytic electrode surfaces.

Main Methods:

• Fabrication of a cobalt-nitrogen-carbon (Co/NC) composite electrocatalyst.
• Electrochemical performance testing of Co/NC modified electrodes in aqueous phenazine RFBs.
• Control experiments and density functional theory (DFT) calculations to analyze reaction mechanisms.

Main Results:

• The Co/NC electrocatalyst improved the energy efficiency of aqueous phenazine RFBs by 43.2% compared to pure carbon felt at 100 mA/cm².
• Co/NC provides increased electrochemical active surface area and more reactive sites.
• DFT calculations revealed that Co modification reduces the energy barrier and introduces new reaction pathways via selective interfacial water behavior.

Conclusions:

• The Co/NC composite electrocatalyst significantly enhances the redox kinetics of phenazine derivatives.
• Synergistic effects between cobalt and the nitrogen-doped carbon support are crucial for improved performance.
• A new mechanism involving selective interfacial water behavior is proposed for enhanced reduction reactions.