Polypyrrole wrapped‐carbon nanotube composites with self‐assembled core‐shell structure for high‐performance flexible supercapacitors

Abstract The polypyrrole wrapped‐carbon nanotube composites with the core‐shell design are prepared via two‐step self‐assembly originated from the multi‐interactions of dopant, zeolitic imidazolate framework, carbon nanotube and pyrrole. The core composed of carbon nanotube effectively improves the conductivity of the composite and provides stable double‐layer capacitance. The shell composed of polypyrrole and tightly wrapped on carbon nanotubes effectively prevents the volume expansion of polypyrrole while undergoing the process of doping/de‐doping as well as endows supercapacitors with high pseudocapacitance. The polypyrrole‐coated carbon nanotube displays a remarkable specific capacitance of 510 F g −1 when operating at a current density of 1 A g −1 . Surprisingly, the assembled polypyrrole wrapped‐carbon nanotube//activated carbon asymmetric supercapacitor not only possesses a high capacitance preservation of 88.5% after 10,000 charge/discharge cycles at 5 A g −1 , but also shows superior flexibility and stable electrochemical behaviors when subjected to various bending angles. Furthermore, the flexible polypyrrole wrapped‐carbon nanotube//activated carbon supercapacitor achieves the superb energy density of 86.3 Wh kg −1 and the power density of 800 W kg −1 when operating at 1 A g −1 . These results highlight the significant potential of this new generation of flexible supercapacitor devices. Highlights Polypyrrole is wrapped on carbon nanotube to form a core‐shell structure CNTs improve the conductivity and provides double‐layer capacitance The core‐shell design prevents the volume expansion of polypyrrole The assembled asymmetric supercapacitor shows superior flexibility