Effect of Long-Chain Ionic Liquids on the Capacitive Performance of Carbon Nanotube-Sulfonated Polyaniline Hydrogels for Energy Storage Applications

Abstract Imidazolium-based ionic liquids (ILs) have been perceived as a promising candidate for bridging polyaniline (PANI) on well-dispersed carbon nanotubes (CNTs) via formation of IL-stabilized multiwalled carbon nanotubes (MWCNTs) dispersion in which outer walls of CNTs, as well as benzene rings of the aniline monomer and the growing polymer, have been potently effective in such procurement. The sulfonated water-soluble PANI-[C16C1im]­Cl-MWCNT nanocomposites (SPANI-IL-MWCNTs) are directly deposited on a graphite-based current collector using a simple and cost-effective electrophoretic deposition (EPD) method. The SPANI-IL-MWCNT electrodes exhibit remarkable electrochemical performance compared to SPANI-MWCNTs in the absence of imidazolium-based ILs. The symmetric supercapacitor (SSC) devices are fabricated using SPANI-IL-MWCNT as the electrode and the electrochemical properties of the SSC devices are investigated. The electrochemical results demonstrate that the SPANI-IL-MWCNT SSC devices exhibit an outstanding energy density (59.3 Wh·kg–1) at a reasonable power density of 187.5 W·kg–1. It also represents remarkable cycling durability (retaining almost over 83.5% of its initial capacitance after 6000 charge–discharge cycles). Findings in this work provide convincing evidence that hierarchical SPANI-IL-MWCNTs could be a potential candidate as an ideal electrode material for high-performance energy storage systems.