Fabrication of Phthalocyanine\nPolymers with Abundant\nNitrogen Active Sites as the Cathode Materials for Aqueous Zinc-Organic\nBatteries

Phthalocyanine (Pc), a macrocyclic aromatic compound,\nhas attracted\nextensive attention in energy storage due to its large π-conjugated\nstructure and abundant nitrogen sites. However, the poor solubility\nof Pc monomers leads to rigorous polymerization conditions, which\nhinder the application and development of Pc-based polymers. Herein,\n1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT(CN)<sub>6</sub>) is used as a precursor to construct Pc-based conjugated polymers\n(Pc-COPs) via a molten salt assisted strategy. The physical–chemical\nproperties of the resulting Pc-COPs at different synthesis temperatures\nwere systematically studied, which indicates that Pc-COP-350 (at the\nsynthesis temperature of 350 °C) exhibits complete polymerization\nwhile maintaining the redox activity of the active centers. As the\ncathode material for aqueous zinc-ion batteries, Pc-COP-350 exhibited\nthe best electrochemical performance, achieving a specific capacity\nof 269 mA h g<sup>–1</sup> at 0.05 A g<sup>–1</sup>.\nThe Coulombic efficiency is up to nearly 100% even after long cycles\nat a current density of 1 A g<sup>–1</sup>. This work provides\na pathway for designing and synthesizing Pc-based macrocyclic compounds.