Supramolecular K⁺ Coordination in Poly(dibenzo-18-crown-6)/SWCNTs Freestanding Electrodes for High-Energy-Density Supercapacitors

The development of freestanding electrodes with high energy density remains a key challenge for potassium-ion supercapacitors. Herein, a supramolecular strategy is presented through the in situ electropolymerization of dibenzo-18-crown-6 (DB18C6) on single-walled carbon nanotubes (SWCNTs) films, fabricating the flexible poly(DB18C6) (PDB18C6)/SWCNTs hybrid electrodes. This design leverages dual charge-storage mechanisms: a conductive SWCNTs network for rapid electron transport and embedded PDB18C6 macrocycles for reversible K + coordination via host-guest interactions, which significantly enhances pseudocapacitance and cycling stability of the prepared film. By optimizing the electropolymerization time, the freestanding electrode achieves a high energy density of 77 Wh kg -1 at a power density of 1595 W kg -1 within an expansive operating window of -1.5 to 1.5 V. Notably, a high capacitance retention of 99.25% is maintained after 15,000 cycles at 10 A g -1 , attributable to the robust K + -crown ether coordination effect. Furthermore, a symmetrical supercapacitor assembled with PDB18C6/SWCNTs electrodes delivers an energy density of 18.75 Wh kg -1 at 1350 W kg -1 . This work underscores the promise of supramolecular coordination chemistry for designing high-performance energy storage devices.