Role of dual dopants in highly ordered crystalline polyaniline nanospheres: Electrode materials in supercapacitors

Aniline is oxidized by ammonium persulfate oxidant with a weak organic acid, 1,3‐(6,7)‐napthalene trisulfonic acid (NTSA), via an aqueous polymerization pathway to polyaniline (PANI) salt. The effects of the sodium lauryl sulfate surfactant, mineral acid [sulfuric acid (H₂SO₄)], and a combination of surfactant with mineral acid in the aniline polymerization reaction are also carried. These salts were designated as PANI–NTSA–dodecyl hydrogen sulfate (DHS), PANI–NTSA–H₂SO₄, and PANI–NTSA–DHS–H₂SO₄, respectively. Interestingly, PANI–NTSA–DHS showed a highly ordered crystalline sample with a nanosphere morphology. These PANIs were used as electrode materials in supercapacitor applications. Among the four salts, the PANI–NTSA–DHS–H₂SO₄ material showed higher values of specific capacitance (520 F/g), energy (26 W h/kg), and power densities (200 W/kg) at 0.3 A/g. Moreover, 77% of the original capacitance was retained after 2000 galvanostatic charge–discharge cycles with a Coulombic efficiency of 98–100%. PANI–NTSA–DHS–H₂SO₄ was obtained in excellent yield with an excellent conductivity (6.8 S/cm) and a thermal stability up to 235°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42510.     

Polyaniline/MnO2 composite with high performance as supercapacitor electrode via pulse electrodeposition

A method of pulse electrodeposition was proposed to synthesize polyaniline (PANI)/MnO₂ composite in aniline, H₂SO₄, and MnSO₄ aqueous solution. The PANI/MnO₂ composite has rod‐like structure and MnO₂ particles are distributed on PANI uniformly. To evaluate the performance of the as‐prepared materials as supercapacitor electrodes, cyclic voltammetry, galvanostatic charge–discharge measurements, and electrochemical impedance spectroscopy were performed. The PANI/MnO₂ composite shows a higher specific capacitance (810 F g⁻¹) than pure PANI (662 F g⁻¹) at a current density of 0.5 A g⁻¹. The cycle life of the composite was also excellent. After 1,000 cycles, it maintained 86.3% of its initial capacitance. POLYM. COMPOS., 36:113–120, 2015. © 2014 Society of Plastics Engineers     

One‐step oxidation of aniline by peroxotitanium acid to polyaniline–titanium dioxide: A highly stable electrode for a supercapacitor

In this study, to make a stable electrode material for a supercapacitor, we selected a polyaniline and titanium dioxide (TiO₂) hybrid material. Peroxotitanium acid was used to oxidize aniline in the presence of sulfuric acid to a poly(aniline sulfate) salt–titanium oxide composite in one step. IR, X‐ray diffraction, and energy dispersive X‐ray analysis (EDAX) analyses supported the formation of the composite. The poly(aniline sulfate) salt–titanium oxide composites (50 wt % each) showed an amorphous, flakelike morphology having a conductivity value of 8 × 10^?3 S/cm with an excellent yield and stability (300°C).This composite material in the cell configuration showed a specific capacitance of 320 F/g at a 0.33 A/g discharge current density. Thirty thousand charge–discharge (CD) cycles at a heavy CD current density of 3.3 A/g were carried out on the supercapacitor cell. The values of equivalent series resistance (ESR) (8–9 Ω) and efficiency (100–98%) were found to be independent of the cycle number with an excellent retention capacity of 83%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41711.     

Electrosynthesis and capacitive performance of polyaniline–polypyrrole composite

The composite of polyaniline and polypyrrole (PPY‐PANI) was prepared by two‐step electrochemical polymerization method. Techniques of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravity analysis (TG/DTG) measurements were used to characterize the morphology and structure of the composite. The electrochemical properties of the composite were investigated by cyclic voltammetry (CV), galvanostatic charge‐discharge, and electrochemical impedance spectroscopy (EIS). The results indicated that the polyaniline–polypyrrole composite showed better electrochemical capacitive performance than polypyrrole (PPY) and polyaniline (PANI). The specific capacitance of the composite electrode was 523 F/g at a current of 6 mA/cm² in 0.5 M H₂SO₄ electrolyte. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Polyaniline salt containing dual dopants,pyrelenediimide tetracarboxylic acid,and sulfuric acid: Fluorescence and supercapacitor

Storage of energy is considered as the most germane technologies to address the future sustainability. In this study, aniline was chemically oxidized with a controlled concentration of pyrelenediimide tetracarboxylic acid (PDITCA) by ammonium persulfate to polyaniline salt (PANI‐H₂SO₄‐PDITCA), with nanorods morphologies, having a sensibly decent conductivity of 0.8 S cm^?1, wherein H₂SO₄ was generated from ammonium persulfate during polymerization. PANI‐H₂SO₄‐PDITCA salt showed bathochromic fluorescence shift (595 nm) compared to PDITCA (546 nm). The Brunauer–Emmett–Teller surface area of the PANI‐H₂SO₄‐PDITCA‐25 and PANI‐H₂SO₄‐PDITCA‐50 were 18.3 and 21.4 m² g^?1, respectively. Furthermore, its energy storage efficiency was evaluated by supercapacitor cell configuration. The composite PANI‐H₂SO₄‐PDITCA‐50 showed capacitance 460 F g^?1 at 0.3 A g^?1 and large cycle life 85,000 cycles with less retention of 77% to its original capacitance (200 F g^?1) even at a better discharge rate of 3.3 A g^?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45456.     

Capacitive performance of polyaniline/manganese dioxide nanofiber microsphere

This work has obtained polyaniline/manganese dioxide (PANI/MnO₂) nanofibers microsphere by interfacial chemical synthesis with 4‐amino‐thiophenol (4‐ATP) as the structure‐directing agent on the Au substrate. The cyclic voltammograms, galvanostatic charge–discharge, and electrochemical impedance spectroscopy were used to determine their capacitive performance. Powder X‐ray diffraction, thermogravimetry and differential scanning calorimetry, Fourier transformed infrared spectroscopy, Brunauer–Emmett–Teller surface area measurements, and scanning electron microscope were performed for physical and chemical characterization. The effect of 4‐ATP and acids on the capacitive performance of PANI/MnO₂ nanofibers microsphere was elucidated. The as‐prepared PANI/MnO₂ was nanofiber about 30 nm diameters, and they further self‐assembled into sphere. Its specific capacitance is up to 765 F g^?1 at 1.0 mA cm^?2 in 1.0M Na₂SO₄ solution. And it shows a high stability with a capacitance fade of only 14.9% after 400 charge–discharge cycles. The symmetric capacitor of PANI/MnO₂ (PM10+)/PANI/MnO₂ (PM10?) is assembled in 1.0M Na₂SO₄ solution, and its capacitive performance is compared with that of PANI (+)/PANI (?) and MnO₂ (+)/MnO₂ (?). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40575.     

Synthesis of copolymer of aniline and pyrrole by inverted emulsion polymerization method for supercapacitor

Copolymer of aniline and pyrrole was synthesized by inverted emulsion polymerization method by oxidizing aniline and pyrrole using benzoyl peroxide in presence of sodium laurylsulphate surfactant and p‐toluenesulphonic acid. Copolymer samples were characterized by infrared, X‐ray diffraction and scanning electron microscopic techniques and compared their properties with the corresponding homopolymers. The optimum reaction conditions for the preparation of copolymer with reasonably good yield (1.72 g) and conductivity (7.3 × 10^?2 S/cm) were established. The synthesis procedure was extended to prepare copolymer samples using various protonic acids. Electrochemical characterization such as cyclic voltammetry, charge‐discharge and impedance were carried out on symmetrical supercapacitor cell consists of poly(aniline‐co‐pyrrole)‐p‐toluenesulfonic acid salt, wherein, the copolymer salt was synthesized using equal amount of aniline and pyrrole monomers. The values of specific capacitance, energy and power densities for poly(aniline‐co‐pyrrole)‐p‐toluenesulfonic acid system (PANI‐PPy) were calculated from charge‐discharge studies and are found to be 21 F/g, 5.7 Wh/Kg and 100 W/Kg respectively. Impedance analysis showed specific capacitance value (57 F/g) at 0.01 Hz at 0.22 V. Among the copolymer salts, copolymer prepared with sulfuric acid showed higher capacitance (66 F/g). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and electrochemical capacitance of poly(pyrrole‐co‐aniline)

The copolymer of pyrrole and aniline, poly(pyrrole‐co‐aniline), has been prepared by chemical oxidation of corresponding monomer mixtures with ammonium peroxysulfate. Techniques of FTIR, SEM‐EDS, and BET surface area measurement were used to characterize the structure and morphology of the copolymer. The electrochemical properties of the copolymer were investigated by cyclic voltammetry, galvanostatic charge‐discharge, and electrochemical impedance spectroscopy. The results indicated that poly(pyrrole‐co‐aniline) was about 100–300 nm in diameter and showed better electrochemical capacitive performance than polypyrrole and polyaniline. The specific capacitance of the copolymer electrode was 827 F/g at a current of 8 mA/cm² in 1 mol/L Na₂SO₄ electrolyte. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of the reaction temperature on polyaniline morphology and evaluation of their performance as supercapacitor electrode

The polyaniline (PANI) nanostructures of tubular, spherical, and granules morphologies were synthesized by chemical oxidation approach in different reaction temperatures and used as the active electrode materials of symmetric redox supercapacitors. X‐ray diffraction and scanning electron microscopy techniques are employed for characterization of these PANIs. With the initial and reaction temperature increase, the morphology of PANI turned from block to spherical and tubular. Electrochemical properties of these PANI electrodes are studied by cyclic voltammetry (CV), agalvanostatic charge–discharge test, and electrochemical impedance spectroscopy (EIS) in 1M H₂SO₄ aqueous solution. The highest electrochemical properties are obtained on the PANI with tubular morphology. The initial specific capacitance of tubular, spherical, and granules PANI are about 300, 300, and 290 F g^?1 at a constant current of 5 mA. Meanwhile, the retention of the tubular PANI capacitance after 500 charge–discharge cycles was 75%, whereas the spherical and granules PANI was only 35% and 57%. The results indicate that tubular PANI electrodes have potential applications as high‐performance supercapacitors electrode materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3753–3758, 2013     

High capacitance properties of polyaniline by electrochemical deposition on a porous carbon substrate

Electrochemical deposition of polyaniline (PANI) is carried out on a porous carbon substrate for supercapacitor studies. The effect of substrate is studied by comparing the results obtained using platinum, stainless steel and porous carbon substrates. PANI deposited at 100 mV s⁻¹ sweep rate by potentiodynamic technique on porous carbon substrate is found to possess superior capacitance properties. Experimental variables, namely, concentrations of aniline monomer and H₂SO₄ supporting electrolyte are varied and arrived at the optimum concentrations to obtain a maximum capacitance of PANI. Low concentrations of both aniline and H₂SO₄, which produce PANI at low rates, are desirable. The PANI deposits prepared under these conditions possess network morphology of nanofibrils. Capacitance values as high as 1600 F g⁻¹ are obtained and PANI coated carbon electrodes facilitate charge-discharge current densities as high as 45 mA cm⁻² (19.8 A g⁻¹). Electrodes are found to be fairly stable over a long cycle-life, although there is some capacitance loss during the initial stages of cycling.     

Electrospun polyaniline nanofibers web electrodes for supercapacitors

Polyaniline nanofibers (PANI‐NFs) web are fabricated by electrospinning and used as electrode materials for supercapacitors. Field‐emission scanning electron microscope micrographs reveal nanofibers web were made up of high aspect ratio (>50) nanofibers of length ～30 μm and average diameter ～200 nm. Their electrochemical performance in aqueous (1M H₂SO₄ and Na₂SO₄) and organic (1M LiClO₄ in propylene carbonate) electrolytes is compared with PANI powder prepared by in situ chemical oxidative polymerization of aniline. The electrochemical properties of PANI‐NFs web and PANI powder are studied using cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. PANI‐NFs web show higher specific capacitance (～267 F g^?1) than chemically synthesized PANI powder (～208 F g^?1) in 1M H₂SO₄. Further, PANI‐NFs web demonstrated very stable and superior performance than its counterpart due to interconnected fibrous morphology facilitating the faster Faradic reaction toward electrolyte and delivered specific capacitance ～230 F g^?1 at 1000th cycle. Capacitance retention of PANI‐NFs web (86%) is higher than that observed for PANI powder (48%) indicating the feasibility of electro spun PANI‐NFs web as superior electrode materials for supercapacitors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and capacitance performance of polyaniline/titanium nitride nanotube hybrid

A polyaniline/titanium nitride (PANI/TiN) nanotube hybrid was prepared and used for an electrochemical supercapacitor application. Firstly, the well-aligned TiN nanotube array was prepared by anodization of titanium foil and subsequent nitridation through ammonia annealing. Then, PANI was deposited into TiN nanotube through the electrochemical polymerization process. The obtained PANI/TiN nanotube hybrid had an ordered porous structure. A high specific capacitance of 1,066 F g^?1 was obtained at the charge–discharge current density of 1 A g^?1 when only the mass of PANI was considered. The specific capacitance can even achieve 864 F g^?1 at 10 A g^?1 and still keep 93 % of the initial capacity after 200 cycles. An aqueous supercapacitor, consisting of two symmetric PANI/TiN nanotube hybrid electrodes and 1.0 M H₂SO₄ electrolyte solution, showed the specific capacitance of 194.8 F g^?1, energy density of 9.74 Wh kg^?1, and power density of 0.3 kW kg^?1.     

Dulse‐derived porous carbon–polyaniline nanocomposite electrode for high‐performance supercapacitors

Dulse‐derived porous carbon (DDPC)–polyaniline (PANI) nanocomposites were fabricated by a method based on the in situ chemical oxidation polymerization of aniline on DDPC. The characterization of the material showed that the nano‐PANI was grown on the surface of DDPC in the form of nanosticks or nanoparticles. The DDPC–PANI nanocomposites were further used as electrode materials for energy‐storage applications. Meanwhile, the effect of the amount of aniline on the electrochemical performance of DDPC–PANI was also investigated. The results show that a maximum specific capacitance of 458 F/g was achieved for the DDPC–PANI nanocomposites; this was higher than that of the DDPC electrode (218 F/g), and the PANI electrode (318 F/g). The specific capacitance of DDPC–PANI remained 66.0% of the initial value after 5000 cycles; this was higher than that of PANI (50.5%). Finally, a device of DDPC–PANI–activated carbon (AC) was assembled with DDPC–PANI as a positive electrode, which exhibited a high energy density of 9.02 W h/kg, which was higher than that of PANI–AC device. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45776.     

Synthesis of polyaniline/MWCNTs by interfacial polymerization for superior hybrid supercapacitance performance

Polyaniline/Multiwalled carbon nanotubes (PANI/MWCNTs) nanocomposite was prepared via liquid-liquid interfacial polymerization method. The morphology studies of the nanocomposite using SEM and TEM techniques confirmed the presence of PANI as aggregates along with MWCNTs and X-ray diffraction studies indicated the presence of graphitic planes of MWCNTs along with PANI in semi-crystalline emeraldine salt form. The PANI/MWCNTs nanocomposite electrode exhibited specific capacitance (Cs) of 1551 F/g at a scan rate of 2 mV/s in aqueous 1 M H₂SO₄ in a potential window of 0–1.2 V. The material exhibited good cycle life with 95% capacitance retention in a life cycle test conducted at 5 A/g for 1000 cycles. Further, an asymmetric supercapacitor device (ASD) was fabricated using PANI/MWCNTs as positive and activated carbon as negative electrodes in aqueous 1 M H₂SO₄. The ASD exhibited a Cs of 142 F/g at a scan rate of 5 mV/s in a wide potential range of 0–1.6 V. The device offered high energy and power densities of 29 Wh/Kg and 7.3 kW/Kg respectively and also demonstrated an excellent cyclic stability by retaining 97% of its initial capacitance after 5000 cycles at high current density of 20 A/g.

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Graphical abstract Schematic representation of design of asymmetric supercapacitor device, its cycle performance and Ragone plot

     

A redox‐mediator‐doped gel polymer electrolyte applied in quasi‐solid‐state supercapacitors

Methylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA‐PVP‐H₂SO₄‐MB) for a quasi‐solid‐state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self‐discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm^?1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA‐PVP‐H₂SO₄‐MB electrolyte is 328 F·g^?1, increasing by 164% compared to that of MB‐undoped system at the same current density of 1 A·g^?1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg^?1. The quasi‐solid‐state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39784.     

Preparation and electrochemical investigation of the polyaniline/activated carbon nanocomposite for supercapacitor applications

The polyaniline (PANI)/activated carbon (AC) nanocomposite electrodes were prepared by electropolymerization of aniline monomers on the surface of AC/polyvinyl alcohol (PVA) electrodes for supercapacitor studies. Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were performed to characterize the structure and morphology of the nanocomposite electrodes. The electrochemical properties of the prepared nanocomposite electrodes and the supercapacitive behavior of the PANI, AC, and AC/PANI/PVA electrodes were investigated using cyclic voltammetry (CV) and galvanostatic charge/discharge measurements, respectively. Morphological studies showed that a thin film of PANI has been uniformly deposited on the porous surface of AC electrode, and an ordered arrangement of nanostructures with interlinked porous network has been made. Electrochemical measurements showed that AC particles prevent the degradation of PANI chains during charge/discharge cycles. The specific capacitance of the AC/PANI/PVA nanocomposite electrode was 338.15 F/g which is higher than that of the pristine AC electrode (0.08 F/g). This is due to the contribution of PANI chains by their pseudocapacitance (redox reaction) properties. Although the specific capacitance of PANI electrode (378.57 F/g) was greater than that of the nanocomposite electrode, the cyclic stability of the PANI electrode was lower than that of the AC/PANI/PVA nanocomposite electrode.     

Fabrication and electrochemical properties of carbon nanotube array electrode for supercapacitors

The multiwalled carbon nanotube (MWNT) array was fabricated by chemical vapor deposition (CVD) in the template of porous alumina from the carbonaceous source of C₂H₂ in the presence of a catalyst of ferric metals. To utilize the external surface other than the inner surface of the carbon nanotubes, 1 mol/L sulfuric acid was applied to remove off the most part of AAO template on the carbon nanotube electrode. The electrochemical performances of the carbon nanotube array electrode were investigated by use of the cyclic voltammetry, galvanostatic charge/discharge and ac impedance methods for its application in supercapacitors. The specific capacitance of 365 F/g of the electrode was achieved with the discharge current density of 210 mA/g in the solution of 1 mol/L H₂SO₄. In addition, the carbon nanotube array electrode was found to have low equivalent series resistance (ESR) and good cycling stability.     

Improved electrochemical performances of polyaniline by graphitized mesoporus carbon: Hybrid electrode for supercapacitor

In this work, graphitized mesoporus carbon (GMC) was used to increase the specific capacitance and cycle stability of polyaniline (PANI). Hybrid material of polyaniline‐graphitized mesoporus carbon (GMCP) was prepared by in situ chemical polymerization of aniline in presence of sulphuric acid using ammonium persulfate oxidant with various amounts of GMC. Formation of hybrid sample was confirmed from X‐ray diffraction, and the composite sample was stable up to 250°C. Morphology, crystalline nature, and electrochemical performance of GMCP were compared with that of its individual components, GMC and PANI. GMC showed particle morphology and PANI showed nanofiber morphology. GMCP2 composite showed nanofibrous form of PANI grown on GMC (spherical form) along with PANI nanofibers. Higher crystallinity was obtained for GMCP than that of PANI. Cycling stability of GMCP2 was carried up to 12,000 cycles at 1200 W kg^?1 and the retention capacitance was 66% of its original capacitance of 243 F g^?1. With the same power density, GMC showed less capacitance value of 53 F g^?1 with 92% retention and PANI showed capacitance of 187 F g^?1 and it underwent 1500 cycles only. Higher supercapacitor performance was obtained for GMCP composite compared to that of its components, PANI and GMC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42540.     

The role of polyaniline salts in the removal of direct blue 78 from aqueous solution: A kinetic study

Three polyaniline salts (PANI–H₂SO₄, PANI–H₃PO₄, and PANI–HNO₃) have been synthesized by chemical oxidative polymerization of aniline. They have been tested as adsorbents for the removal of the textile dye direct blue 78 (DB78) from aqueous solution. The interaction followed pseudo-second-order kinetics whether the rate of interaction was measured from the depletion of dye concentration in solution or the increase in the amount of dye adsorbed on the PANI surface. The removal rate was a function of the activity of the polymer as well as the reaction parameters of the polymer/dye system. The activity of the PANI depended on the polymerization conditions. These conditions involve the concentration of aniline, ammonium peroxydisulfate as oxidant, and sodium dodecylsulfate (SDS), the type of dopant acid (H₂SO₄, H₃PO₄, HNO₃), and the polymerization time. Higher removal rate was observed at oxidant/aniline mole ratio equals 1. The rate of removal was in the order PANI–H₃PO₄ > PANI–H₂SO₄ > PANI–HNO₃. The rate decreased with increasing the concentration of DB78 and pH. It increased with increasing the load of PANI. Pseudo-second-order kinetics, external surface adsorption, and intraparticle diffusion models were concurrently operating in the removal of DB78 with PANI.     

交联状聚苯胺包覆碳纤维复合纳米线 制备及电容特性

以交联状氮掺杂碳纳米纤维(CNF)为碳骨架,采用插层辅助原位氧化聚合法使聚苯胺(PANI)均匀地在CNF表面包覆生长,制备了交联状聚苯胺包覆碳纤维(PANI/CNF)复合纳米线。采用TEM、SEM、TG、FTIR、Raman、XRD、XPS和BET对PANI/CNF复合纳米线的形貌和结构进行了表征。通过CV、EIS和GCD测试了PANI/CNF复合纳米线的电容特性。结果表明:PANI/CNF复合纳米线相互连通,表面呈荆棘状,具有多级空间结构。CNF质量分数为40%的PANI/CNF40复合纳米线电极在电流密度为1.0 A/g时,比电容达到820.31 F/g。电流密度增加到20.0 A/g时,比电容保留率为74.8%。在10.0 A/g时,经过2000次充放电循环后电极的比电容保持率达到89.7%。