Synergistic effect between redox additive electrolyte and PANI-rGO nanocomposite electrode for high energy and high power supercapacitor

• Published in: Electrochimica acta 2017-02, Vol.228, p.290-298
• Main Authors: Mousavi, Mir F., Hashemi, Masumeh, Rahmanifar, Mohammad S., Noori, Abolhassan
• Format: Article
• Language: English
• Subjects: Capacitance; Catechol; Current density; Density; Electrical resistivity; Electrochemical analysis; Electrodes; Energy storage; Flux density; High energy; Ion transport; Nanocomposites; Nanotubes; Polyaniline rectangular nanotube; Polyanilines; reduced graphene oxide; Studies; Supercapacitor; Supercapacitors; Synergistic effect; Synthesis
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2017.01.027

•We used a simple and convenient SDS-templated method to synthesize rectangular PANI nanotubes.•We used a fast and facile method to prepare PANI-rGO nanocomposite.•PANi-rGO in catechol-incorporated electrolyte exhibited improved electrochemical performance.•Synergistic effect between catechol and PANI offered exciting charge storage capabilities.•We obtained capacitance of 1967F/g (in 3E) and 409F/g (for device) at 1.0A/g. Supercapacitors (SCs), as high power density energy storage resources, have recently attracted considerable attention. Increasing the energy of supercapacitors is a key parameter to success in achieving far more demanding energy storage applications. There are two approaches to achieve this goal: the first is to widen the operating potential window, and the second is to develop emerging capacitive or pseudocapacitive materials. Polyaniline (PANI) with different morphologies, and hence different supercapacitive performances, has been considered as one of the intriguing active materials due to its high conductivity, intrinsic flexibility, and high redox active specific capacitance. In this work, we report on a simple and convenient method to synthesize PANI nanotubes with rectangular morphology. Then we synthesized PANI/reduced graphene oxide (PANI-rGO) nanocomposite via a convenient electrochemical reduction process. We investigated electrochemical performance of the electrode in the presence and absence of catechol, as a redox-additive molecule incorporated into the electrolyte, by CV, EIS and GCD methods. With incorporation of the catechol in the electrolyte the operating potential window of the electrode increased from 1.0 to 1.2V, and its capacitance boosted about 5-fold from 429 to 1967F/g at a current density of 1A/g. The astonishing supercapacitive performance of the electrode is attributed to; (i) the rectangular nanotube morphology of the PANI, which provides both a better electrical conductivity and a facilitated ion transport pathway, and (ii) the synergetic effect between PANI-rGO and catechol. The electrode showed a superior long cycle life with 81% retention of the initial specific capacitance after 5000 cycles, and demonstrated an excellent rate capability with specific capacitances of 267 and 546F/g, at a current density of 20A/g, in the absence and presence of catechol, respectively. Furthermore, we fabricated a symmetric device using the PANI-rGO film on a flexible stainless steel substrate in the catechol-containing ele