Rational Molecular Design of a Multi-Electron Organic Anode via Rapid Microwave Synthesis for Ultrastable NH₄ ⁺...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous ammonium-ion batteries (AAIBs) show promise for energy storage but require advanced electrode materials.
• Small organic molecules offer tunable structures but face challenges like slow synthesis, limited active sites, and electrolyte dissolution.

Purpose of the Study:

• To design and synthesize a novel small organic molecule, DNQP, with enhanced electrochemical properties for AAIBs.
• To develop a rapid synthesis method for high-performance organic electrode materials.

Main Methods:

• Microwave-assisted synthesis of the DNQP molecule, featuring multiple redox-active centers (C═O/C═N).
• Electronic structure analysis to understand the material's bandgap, π-conjugation, and charge transport properties.
• Electrochemical testing of DNQP as an electrode material in AAIBs, including capacity, cycling stability, and full-cell performance.
• Mechanism studies to elucidate the ammonium ion storage process.

Main Results:

• Rapid microwave synthesis of DNQP in 40 minutes, significantly faster than conventional methods.
• DNQP exhibits an ultranarrow bandgap (1.053 eV), extended π-conjugation, and efficient π-π stacking for charge transport.
• High redox-site utilization (79%) delivering a four-electron capacity of 155.9 mAh g⁻¹ at 0.1 A g⁻¹.
• Exceptional cycling stability with 12,000 cycles at 5 A g⁻¹ and a full cell retaining 99% capacity after 2000 cycles.
• Mechanism elucidation reveals a reversible four-electron NH₄⁺ storage via hydrogen bonding.

Conclusions:

• The rationally designed DNQP molecule demonstrates superior electrochemical performance for AAIBs.
• Rapid microwave synthesis offers a viable route for producing high-performance organic electrode materials.
• This work provides a pathway for developing advanced organic materials for next-generation energy storage devices.