Boosted Durability and Diffusion Kinetics of High-Potential Azopyridines for Aqueous Organic Flow Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-energy-density aqueous organic flow batteries (AOFBs) require stable, high-potential organic redox-active molecules.
• Azopyridine (AZO) derivatives offer high redox potential but suffer from instability and slow kinetics.

Purpose of the Study:

• To enhance the stability and redox kinetics of AZO derivatives for improved AOFB performance.
• To achieve dual-target modulation of electronic structure and steric hindrance to stabilize the azo bond.
• To optimize solvation shell anions for reduced aggregation and reorganization energy.

Main Methods:

• Dual-target molecular modulation of electronic structure and steric hindrance.
• Modification of solvation shell anions.
• Electrochemical characterization and long-term cycling tests of AZO-based AOFBs.

Main Results:

• Increased azo bond energy and buffered structural changes, suppressing side reactions.
• Enhanced redox potential to 0.9 V vs. SHE and improved stability.
• Achieved ~60% increase in cell energy efficiency by optimizing solvation.
• Demonstrated robust durability with 7000 cycles (>1400 h) and high energy density (70.4 Wh L^-1).

Conclusions:

• An integrated molecular and solvation-structure design paradigm was established for durable, high-energy-density AOFBs.
• The developed AZO derivatives show significant promise for next-generation energy storage systems.
• This approach overcomes key limitations of organic redox-active materials in flow batteries.