Three-dimensional, free-standing polyaniline/carbon nanotube composite-based electrode for high-performance supercapacitors
By Malik, Rachit; Zhang, Lu; McConnell, Colin; Schott, Michael; Hsieh, Yu-Yun; Noga, Ryan; Alvarez, Noe T.; Shanov, Vesselin
Published in Carbon
2017
Abstract
Abstract Vertically aligned Carbon Nanotube (CNT) arrays are synthesized directly on {CNT} sheets used as substrates by plasma enhanced chemical vapor deposition (PECVD) in {NH3} plasma environment. The resulting 3-D nanostructured, N-doped {CNT} (NCNT) architecture combines high conductivity and superior mechanical properties of {CNT} sheets with porous structure and high electrochemical activity of {CNT} arrays. {NCNT} sheets are then used as scaffolds for polyaniline (PANI) deposited by electrodeposition. {PANI} coating thickness is optimized to create a core-shell morphology with {PANI} shell supported by {CNT} core. Freestanding and flexible PANI/NCNT electrodes are fabricated without using any metal supports/foil or binders with the {CNT} sheets serving as current collectors. PANI/NCNT electrodes with 56 wt% polymer content demonstrate a gravimetric capacitance of 359 F/g at a current density of 1.56 mA/cm2. The electrode also shows high rate capabilities and retains 82% of original capacitance after current density is increased 30-fold to 46.87 mA/cm2. PANI/NCNT electrodes are used to assemble a symmetric supercapacitor device with PVA/H2SO4 hydrogel as separator and electrolyte. The flexible PANI/NCNT supercapacitor showed a specific capacitance of 128 F/g at 2.47 A/g current density and retained over 92% of initial capacitance after 10000 cycles of charge-discharge at 24.7 A/g current density.