Electrochemical Copolymerization of 1,10-Phenanthroline-5,6-dione and o -Methoxyaniline and Application for Aqueous Electrochemical Energy Storage

An organic conducting copolymer, poly(1,10-phenanthroline-5,6-dione-co-o-methoxyaniline) (PPD-co-OMA), is synthesized using an electrochemical polymerization method on a carbon paper substrate and is utilized as the electrode material for energy storage in an aqueous electrolyte. PPD-co-OMA possesses a highly interconnected porous morphology and exhibits a high specific capacity of 183.3 mAh g–1 at a current density of 1 A g–1 in 1 M H2SO4. Compared to the homopolymers poly(1,10-phenanthroline-5,6-dione) (PPD) and poly(o-methoxyaniline) (POMA), lower charge transfer resistance, abundant redox-active sites, and improved ion diffusion contribute to the enhanced charge storage performance of PPD-co-OMA. The charge storage mechanism involves the reversible redox transitions of carbonyl/hydroxyl groups and amino/imino groups, accompanied by reversible H+ intercalation/deintercalation. The symmetric solid-state supercapacitor constructed using two PPD-co-OMA electrodes demonstrates good durability, with a capacity retention of 87.2% after 2000 charge and discharge cycles at a current density of 5 A g–1. The device exhibits an energy density of 65.8 Wh kg–1 at a power density of 1280 W kg–1. These results demonstrate that the electrocopolymerization strategy provides a facile route for constructing conducting polymers as electrode materials with improved electrochemical energy storage performance.