Fabrication of Phthalocyanine Polymers with Abundant Nitrogen Active Sites as the Cathode Materials for Aqueous Zinc-Organic Batteries

Phthalocyanine (Pc), a macrocyclic aromatic compound, has attracted extensive attention in energy storage due to its large π-conjugated structure and abundant nitrogen sites. However, the poor solubility of Pc monomers leads to rigorous polymerization conditions, which hinder the application and development of Pc-based polymers. Herein, 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT(CN)6) is used as a precursor to construct Pc-based conjugated polymers (Pc-COPs) via a molten salt assisted strategy. The physical–chemical properties of the resulting Pc-COPs at different synthesis temperatures were systematically studied, which indicates that Pc-COP-350 (at the synthesis temperature of 350 °C) exhibits complete polymerization while maintaining the redox activity of the active centers. As the cathode material for aqueous zinc-ion batteries, Pc-COP-350 exhibited the best electrochemical performance, achieving a specific capacity of 269 mA h g–1 at 0.05 A g–1. The Coulombic efficiency is up to nearly 100% even after long cycles at a current density of 1 A g–1. This work provides a pathway for designing and synthesizing Pc-based macrocyclic compounds.