Unlocking Multielectron Transfer in a Quinone-Pyrazine Conjoined Redox Core for Capacity-Doubled and Ultrastable...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous organic redox flow batteries (AORFBs) are crucial for grid-scale energy storage but face limitations in energy density and long-term stability.
• Developing high-performance organic charge carriers is essential to overcome these challenges.

Purpose of the Study:

• To introduce a novel fused-ring molecule, DAPQ, designed to enhance energy density and stability in AORFBs.
• To investigate the impact of π-conjugated architecture and rigid fused-ring structure on battery performance.

Main Methods:

• Synthesis and characterization of DAPQ, an anthraquinone-phenazine fused molecule.
• Assembly and testing of AORFBs utilizing DAPQ as the active material.
• Electrochemical performance evaluation, including energy density, capacity retention, and cycling stability at elevated temperatures.
• Mechanistic studies to elucidate degradation pathways and stabilization effects.

Main Results:

• The 0.6 M DAPQ-based AORFB achieved a high energy density of 53.59 Wh L^-1.
• A 0.5 M DAPQ-based AORFB demonstrated excellent capacity retention (99.86% over 2,300 cycles) with minimal daily decay (0.0017%).
• Stable performance was maintained at 50 °C, highlighting the molecule's thermal stability.

Conclusions:

• The DAPQ molecule, with its π-conjugated architecture and rigid fused-ring structure, significantly improves AORFB energy density and cycle life.
• Extended π-conjugation and balanced charge distribution are key factors in stabilizing redox cores and inhibiting parasitic reactions.
• This conjugation-driven multielectron design offers a new paradigm for developing durable and high-capacity organic charge carriers for sustainable grid-scale energy storage.