In Situ Electrochemical Polymerized Bipolar-Type Poly(1,5-diaminonaphthalene) Cathode for High-Performance Aqueous Zinc-Organic Batteries

Electroactive organic materials, characterized by their flexible molecular architecture and rapid reaction kinetics, demonstrate an enormous potential for applications in aqueous zinc-ion batteries (AZIBs). However, small-molecule organic electrode materials often encounter dissolution-induced capacity decay, whereas polymeric counterparts, despite their limited solubility in electrolytes, confront poor conductivity issues. To tackle these challenges, optimizing molecular structures and synthesis routes is paramount. In this study, we have elaborately designed an electrochemical polymerized poly(1,5-diaminonaphthalene), termed PDAN-1, as a high-performance cathode material for AZIBs. Compared to the chemically polymerized counterpart, termed PDAN-2, PDAN-1 exhibits significantly enhanced electrochemical performance, owing to its markedly reduced electrochemical resistance. Specifically, the PDAN-1 cathode achieves a high discharge capacity of 243 mAh g^-1 at a current density of 0.1 A g^-1. Additionally, it exhibited long-term cycle stability, retaining over 85% of its capacity even after 2700 cycles at 2 A g^-1. Impressively, even under a substantial mass loading of 10 mg cm^-2, PDAN-1 maintains a discharge capacity of 170 mAh g^-1, underscoring its vast potential for practical applications in AZIBs. Furthermore, ex situ analyses and density functional theory calculations collectively reveal that the PDAN-1 cathode operates through a bipolar-type charge storage mechanism, providing insights into its unique electrochemical behavior and further validating its suitability for AZIB applications.