Benzo[c]cinnoline Organic Anode Enables 1.3 V-Class Alkaline Aqueous Batteries

Abstract

Benzo[c]cinnoline (1) is investigated as a low-potential organic anode material for alkaline aqueous batteries (AABs). As organic materials are typically poor catalysts for hydrogen evolution reaction (HER), anode prepared with 1 can significantly reduce the rate of hydrogen production and self-discharge, common issue with conventional metal hydride anodes. Galvanostatic charge–discharge tests of 1 paired with a Ni(OH)₂ cathode in an alkaline aqueous electrolyte (4 M KOH + 2 M KF + 2 M K₂CO₃) show a cell voltage of 1.3 V and a capacity of 229 mAh g^–1, with negligible capacity fading after 1000 cycles. The full cell, with a high loading of 11.1 mg cm^–2, delivers a specific energy of 67 Wh kg^–1 (including both the anode and cathode masses). Furthermore, the electrode of 1 can be produced from the low-cost precursor 2,2′-dinitrobiphenyl (2, $1.64/g) via in situ electrochemical reduction, enhancing its potential for large-scale implementation.