An ultra-stable reference electrode for scaled all-vanadium redox flow batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage Systems

Background:

• Redox flow batteries (RFBs) are promising for grid energy storage due to their scalability, safety, and longevity.
• Understanding RFB reliability and degradation mechanisms is critical but hindered by the lack of stable reference electrodes (REs) in scaled cells.
• Accurate monitoring of individual electrode potentials is essential for diagnosing performance issues in RFBs.

Purpose of the Study:

• To develop an ultra-stable reference electrode (RE) suitable for scaled all-vanadium RFBs.
• To enable in situ monitoring of individual electrode potentials during long-term cycling.
• To investigate the reliability and degradation mechanisms of scaled RFBs by decoupling electrode contributions.

Main Methods:

• Development of a novel dynamic hydrogen electrode (DHE) based RE with optimized platinum electrode area and surface roughness.
• Implementation of the RE for in situ monitoring of individual electrode potentials over 500 cycles in a scaled all-vanadium RFB.
• Analysis of voltage profiles, overpotentials, and polarization curves in conjunction with RE measurements.

Main Results:

• The newly developed RE demonstrated high accuracy and long-term stability in scaled all-vanadium RFBs.
• The RE successfully enabled in situ monitoring of individual cathode and anode potentials throughout 500 cycles.
• Decoupling electrode potentials revealed diverse degradation behaviors between the cathode and anode.

Conclusions:

• The developed ultra-stable RE is a valuable tool for assessing the reliability and degradation of scaled RFBs.
• This work provides fundamental insights into the differential behavior of electrodes in all-vanadium RFBs.
• The findings will aid in the future design of stable REs for energy storage systems and improve RFB performance.