Facile Construction of Three-Dimensional Architectures of a Nanostructured Polypyrrole on Carbon Nanotube Fibers and Their Effect on Supercapacitor Performance

Conducting polymer and carbon nanotube hybrids have been researched intensively in recent years for electrodes of fiber-shaped supercapacitors (FSSCs) toward flexible and wearable energy storage devices. Here, three-dimensional (3D) hierarchical polypyrrole (PPy)/carbon nanotube fiber (CNTF) architectures have been prepared by a facial electrodeposition method for flexible FSSC electrodes. PPy nanoparticles, vertically aligned nanowire arrays (VANAs), and nanowire networks were synthesized on CNTFs, respectively, to construct three types of 3D architectures by controlling the electrodeposition condition of PPy. The influence of the 3D architectures of PPy/ CNTF electrodes on the performance of the assembled quasi-solid-state FSSCs has been carefully studied. The FSSCs with PPy VANAs showed a much higher specific capacitance than that with PPy nanoparticles because the hierarchical porous structure of PPy VANAs provides a higher accessibility of electrolytic ions and a higher Coulombic efficiency than that with the PPy nanowire network. The PPy VANA-/CNTF-based FSSCs displayed high flexibility, stability, and a specific capacitance of 178.14 F g-1 at 0.4 A g-1, which is much higher than that based on common PPy cauliflower-like film/CNTF electrodes (92.06 F g-1) and pure CNTF electrodes (8.48 F g-1) under the same conditions, demonstrating the great advantages of the 3D hierarchical structure.