Doping Effect of Anthraquinone-Based Sulfate on the Supercapacitive Performance of Metal–Organic Framework/Polypyrrole Composites

Abstract

The applications of metal−organic frameworks (MOFs) with intrinsic porous structures are still limited by their low electrical conductivity. Herein, different anthraquinone-based dopants bearing with hydroxyl and sulfonate groups are introduced in situ and anchored on the surface of MOFs to enhance the electrical conductivity during the polymerization of Ni-MOF/ polypyrrole (PPy) composites. The doping effect and electrochemical storage mechanism of MOF/PPy composites are investigated using supported experiments and density functional theory. Results show that among the three redox dopants, AQS demonstrates the highest doping level. The specific capacitance of the resulting Ni-MOF/PPy/AQS-12 can reach a high value of 667 F g −1 at the current density of 1 A g −1 . The assembled Ni-MOF/PPy/AQS-12//active carbon asymmetric supercapacitor device have energy and power densities of 46.7 W h kg −1 (83.3 μWh cm −2 ) and 400 W kg −1 (800 μW cm −2 ), excellent cyclic stability with a capacitance of 90.5% retention after 10000 cycles, and flexible stability, offering great potential as a power source for flexible wearable devices.