Rational Molecular Design of a Multi‐Electron Organic Anode via Rapid Microwave Synthesis for Ultrastable NH ₄ ⁺ Storage

ABSTRACT

Aqueous ammonium‐ion batteries (AAIBs) are promising energy storage devices, yet their development is hindered by the lack of high‐performance electrode materials. While small‐organic molecules possess structural tunability and diverse redox activity, their application is often limited by tedious synthesis, insufficient active‐sites, and dissolution in electrolytes. Herein, we synthesize a small‐organic molecule, DNQP, featuring multiple C═O/C═N redox‐active centers, via a rapid microwave route. This method completes the condensation between –NH ₂ and C═O in 40 min (vs. 72 h for solvothermal), simultaneously introducing additional redox‐active C═N bonds and extending the π‐conjugated framework. Electronic structure analyses reveal that DNQP possesses an ultranarrow bandgap (1.053 eV), a highly delocalized π‐conjugated framework, and favorable π–π stacking channels for charge transport. These features, combined with a chelation‐coordination storage mechanism, enhance electron transfer, structural stability, and multi‐electron reactivity. As a result, DNQP achieves 79% redox‐site utilization, delivering a four‐electron capacity of 155.9 mAh g ⁻¹ at 0.1 A g ⁻¹ , and exhibits remarkable cycling performance over 12 000 cycles at 5 A g ⁻¹ . A DNQP//α‐MnO ₂ full‐cell retains 99% capacity after 2000 cycles. Mechanism studies elucidate a reversible two‐step, four‐electron NH ₄ ⁺ storage process governed by N─H⋯O/N─H⋯N H─bonding. This work offers a rational molecular design and rapid synthesis for high‐performance AAIBs organic materials.