Flexible symmetric and asymmetric supercapacitors based in nanocomposites of carbon cloth/polyaniline - carbon nanotubes

Abstract

This paper describes the construction of flexible symmetric and asymmetric supercapacitors made of carbon cloth, polyaniline and carbon nanotubes. The electrode materials (nanostructures of polyaniline-carbon nanotubes, PANI-CNT) were supported on carbon cloth acting as current collector. PANI-CNT nanostructures were synthesized through an oxidative polymerization process in the monomer (aniline) acid solution with the presence of a surfactant and the addition of multi-walled CNT. The CNT were used with and without pretreatment. The cells electrolyte was H2SO4 0.5 M and the selected potential range was 1 V. In order to test their behavior, the different cells configurations were evaluated by electrochemical techniques. Polyaniline nanostructures and polyaniline-carbon nanotubes nanocomposites were used to make the negative and/or positive electrodes of the cell. The cathode in the asymmetric supercapacitors was always carbon cloth/carbon black. The behavior of the arrayed supercapacitors was evaluated by cyclic voltammetry, between 0.0 and 1.0 V at different scan rates (10–100 mVs−1), as well as with galvanostatic charge/discharge runs at current densities between 0.3 and 6.7 mAcm−2. At a constant current density of 0.3 mA cm−2, a specific capacitance value of 1275 Fg−1 was obtained for a symmetric assembly using both electrodes prepared with polyaniline and carbon nanotubes nanocomposites. When the set was asymmetric, being the positive electrode made of polyaniline and carbon nanotubes nanocomposites, the specific capacitance value was 1566 Fg−1. For the latter array, the specific power and energy density values were 125 Wkg−1 and 217 Whkg−1 at 0.25 Ag−1, and 2502 Wkg−1 and 71 Whkg−1 at 5.0 Ag−1. These results suggest a good energy transfer capacity. Moreover, symmetric and asymmetric supercapacitors demonstrated a high stability over 1000 cycles obtaining a capacitance retention of more than 85%.