Amorphization Unlocks Active Sites in Organic Small Molecules for Ah‐Level Aqueous Ammonium‐Ion Batteries

ABSTRACT

The performance of most organic rechargeable batteries is strongly hindered by insufficient active site exposure arising from strong molecular stacking. To address this issue, an amorphization strategy is implemented to disrupt strong intermolecular π–π stacking in the small molecule 2,3,7,8‐tetraamino‐5,10‐dihydrophenazine‐1,4,6,9‐tetraone (TDT), thereby improving electrolyte accessibility and activating buried redox sites. Amorphous TDT exhibits a high specific surface area of 738 m ² g ⁻¹ , delivers 242.8 mAh g ⁻¹ at 0.1 A g ⁻¹ , and retains 87.1% of its initial capacity after 817 cycles over 2900 h. In situ ATR‐FTIR and EQCM‐D measurements reveal that NH ₄ ⁺ is preferentially adsorbed and stored through coordination and deprotonation, while interfacial NH ₄ ⁺ accumulation induces localized hydrolysis to generate H ₃ O ⁺ for subsequent proton storage. The TDT||CuFe‐PBA full cell retains 100% of its initial capacity over 100 000 cycles at 5 A g ⁻¹ . Moreover, the first Ah‐level AAIB pouch cell delivers 1.037 Ah at an average voltage of 1.14 V, demonstrating the practical promise of amorphous organic small molecule for durable, high capacity AAIBs.