Cu-doped poly(1,8-diaminonaphthalene) enables high-rate and long-cycle stability for quasi-solid-state supercapacitors

The widespread adoption of aqueous polymer-based supercapacitors is significantly hampered by issues such as limited operating potential windows and low energy density. To address these challenges, this study introduces a straightforward and rapid approach involving the incorporation of an active metal, copper (Cu), into a conductive polymer matrix, poly(1,8-diaminonaphthalene), to fabricate an asymmetric supercapacitor configuration (CP//AC). This strategy aims to broaden the potential window of individual cells within aqueous electrolytes, thereby enhancing energy density. The synthesized polymer composite (CP) features a layered nanoflake morphology that facilitates conduction pathways, substantially boosting electron transfer and ion mobility rates. Notably, the CP electrode (CP-2) achieves a specific capacity of 935 mAh g−1 at 3 A g−1 and demonstrates cycling stability with negligible capacity loss over 10 000 cycles at 20 A g−1 in a three-electrode system, corresponding to a maximum power density of 8249 W kg−1 and energy density of 189 Wh kg−1. Upon fabrication of a flexible quasi-solid-state supercapacitor using CP-2//AC, an 80.3% capacity retention is observed after 1500 charge–discharge cycles at 15 A g−1. This research highlights the potential of polymeric materials for energy storage and demonstrates their feasibility in flexible aqueous supercapacitor technologies.