Fabrication and electrochemical performances of porous carbon nanotubes/polyaniline-modified carbon nanotube fiber

A porous carbon nanotube (CNT) network was deposited on the surface of carbon nanotube fibers (CNF) by low-potential electrophoretic deposition, and then a layer of polyaniline (PANI) was electrochemically deposited on the surface of the CNT-decorated carbon nanotube fiber to form a core-sheathed structure of three-dimensional porous CNF/CNT/PANI fiber electrode material. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy were used to characterize the morphology and microstructure of the electrode material surface. An electrochemical workstation was used to measure the electrochemical performances. The experiment results showed the porous CNTs framework provided more active sites for the redox reaction of PANI, while the PANI can immobilize the pre-deposited CNTs structure. The areal specific capacitance of the electrode modified with CNTs and PANI reached 77.28 mF·cm^-2 at the current density of 1 mA·cm^-2. Besides, a symmetrical all-solid-state flexible supercapacitor was prepared by using polydimethylsiloxane (PDMS) thin film as the substrate and PVA-H₃PO₄ as the electrolyte, and the areal specific capacitance achieved 61.25 mF·cm^-2 at the current density of 0.25 mA·cm^-2. After 4000 cycles of charge/discharge, the capacitance value remains 80%, and two capacitors in series can light up a 1.8 V LED bulb.