PVP derived nitrogen-doped porous carbon integrated with polyindole: nano/microspheres assembled by emulsion polymerization for asymmetric supercapacitors

The introduction of a carbon scaffold with excellent electrical conductivity is a satisfactory strategy to improve the poor energy storage performance of polyindole (PIn). Herein, a series of PIn integrated with nitrogen-doped porous carbon (NPC) materials are synthesized via facile emulsion polymerization. The morphology, composition and elemental state of as-prepared nano/microspheres are investigated by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and X-ray photoelectron spectroscopy. The supercapacitive performance is evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. It is shown that the morphology and size of NPC@PIn composites can be well-controlled by adjusting the contents of NPC. The as-prepared NPC@PIn based electrode has a high specific capacitance of 286.2 F g(-1) at 0.5 A g(-1) and satisfactory cycling stability (88.9% specific capacitance retention after 3000 charge/discharge cycles) in 1.0 M H2SO4 electrolyte. Furthermore, with a broad voltage window of 1.5 V, the as-assembled NPC@PIn-2//Ti3C2Tx asymmetric supercapacitor achieves a high specific energy of 30.4 W h kg(-1) at a specific power of 750 W kg(-1) and excellent cycling stability (87.8% retention after 3000 cycles). The above results demonstrate that construction of carbon-supported PIn-based electrodes is an effective strategy to improve the application in energy storage.

Automated summary

The introduction of a carbon scaffold has improved the energy storage performance of polyindole. In this study, nitrogen-doped porous carbon materials are integrated with polyindole through emulsion polymerization to form composites. The morphology and size of the composites can be controlled by adjusting the carbon content. The resulting electrode exhibits high specific capacitance and cycling stability in sulfuric acid electrolyte. Moreover, the assembled asymmetric supercapacitor shows high specific energy and excellent cycling stability.