A Highly Stable Azo-Network Polymer Formed via In Situ Electroreductive Coupling among the Polynitro Monomers in Aqueous Zinc-Organic Batteries.

Organic compounds have provided promising alternatives for sustainable aqueous zinc batteries. However, the electrochemical performance of current organic electrodes still lags behind their inorganic counterparts, with rapid capacity fade and slow kinetics posing limitations to practical applications. In this study, a molecule that introduced nitro groups into a quinone-pyrazine type organic core: 2,7,13,18-tetranitro-9,11,20,22-tetraazatetrabenzo[a,c,l,n]pentacene-10,21-dione (TABQ-DNPQ) was synthesized, and an electrochemical conversion of nitro groups to azo groups was observed in a water electrolyte. Upon reduction of -NO2 to N═N, a continuous conjugated azo nanosheet-type polymer, azo TABQ-PQ, was obtained. The introduction of the azo groups is expected to further enhance cyclic stability, especially under high current density conditions, where its fully conjugated core with strong π electron delocalization and intermolecular interactions ensures excellent electronic conductivity, dynamic and electrochemical stabilities. Based on the above reasons, the azo TABQ-PQ exhibited high reversibility in the insertion/removal process of positive ions during charging and discharging. This work provides valuable insights into the structural design of organic-based electrodes with ultrahigh dynamics and electrochemical stability, enabling their operation at ultrahigh current densities (20 and 50 A g-1) while maintaining high specific capacity and long-term stability.