Skeletal Rearrangement of Azo Compounds Enables Low-Potential, High-capacity Organic Anodes for Rechargeable Alkaline...

The widespread adoption of rechargeable alkaline batteries is plagued by the performance-limiting metal anodes, which are prone to (electro)chemical corrosion and raise environmental or economic concerns. Organic redox-active materials offer a potential solution, but they typically struggle with dissolution-induced degradation and insufficiently negative reduction potentials. Herein, we introduce benzo[c]cinnoline and its derivatives (collectively referred to as BCCs), a class of aromatic azo compounds with fused-ring structure, as promising organic anode materials. BCCs exhibit pronounced aromaticity and Brønsted basicity, conferring low reduction potentials and intrinsic insolubility in alkaline solutions. Paired with the industrially established nickel hydroxide cathode, these batteries deliver excellent capacity (297 mAh g^-1 _anode), high output voltage of 1.3 V, and extended cycle life (≈16000 cycles). Notably, they also operate efficiently at extremely low temperatures down to -85 °C with an 8 M KOH electrolyte. We further explore the feasibility for all-organic alkaline batteries by paring BCCs with the dihydro form of 4,4'-azopyridine, utilizing azo compounds for both anode and cathodes. This chemistry harnesses the unique properties of small organic molecules to enable all-organic batteries with high capacity of 236 mAh g^-1, fast charging at 1200 C, and easy recyclability.