Fabrication of carbon nanotubes/polypyrrole/carbon nanotubes/melamine foam for supercapacitor

The carbon nanotubes (CNTs) have been loaded on the melamine foam (MF) to form the composite (CNTs/MF) by dip‐dry process, then polypyrrole (PPy) is coated on CNTs/MF (PPy/CNTs/MF) through chemical oxidation polymerization by using FeCl₃·6H₂O adsorbed on CNTs/MF as oxidant to polymerize the pyrrole vapor. Finally, CNTs are coated on the surface of PPy/CNTs/MF to increase the conductivity of the composite (CNTs/PPy/CNTs/MF) by dip‐dry process again. The composites have been characterized by X‐ray diffraction spectroscopy, scanning electron microscopy and electrochemical method. The results show that the structure of the composites has obvious influence on their capacitive properties. According to the galvanostatic charge/discharge test, the specific capacitance of CNTs/PPy/CNTs/MF is about 184 F g^?1 based on the total mass of the composite and 262 F g^?1 based on the mass of PPy (70.2 wt % in the composite) at the current density of 0.4 A g^?1, which is higher than that of PPy/CNTs/MF (120 F g^?1 based on the total mass of the composite and 167 F g^?1 based on the mass of the PPy). Furthermore, the capacitor assembled by CNTs/PPy/CNTs/MF shows excellent cyclic stability. The capacitance of the cell assembled by CNTs/PPy/CNTs/MF retains 96.3% over 450 scan cycles at scan rate of 20 mV s^?1, which is larger than that assembled by CNTs/PPy/MF (72.5%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39779.     

Multiwalled carbon nanotubes/polypyrrole/graphene/nonwoven fabric composites used as electrodes of electrochemical capacitor

The reduced graphene oxide/nonwoven fabric (rGO/NWF) composites have been fabricated through heating the NWF coated with the mixture of GO and HONH₂·HCl at 130°C, during which the GO is chemically reduced to rGO. Then the composites of polypyrrole (PPy)/rGO/NWF have been prepared through chemically polymerizing pyrrole vapor by using the FeCl₃·6H₂O adsorbed on rGO/NWF substrate as oxidant. Finally, multiwalled carbon nanotubes (MWCNTs) are used as conductive enhancer to modify PPy/rGO/NWF through dip‐dry process to obtain MWCNTs/PPy/rGO/NWF. The prepared composites have been characterized and their capacitive properties have been evaluated in 1.0M KCl electrolyte by using two‐electrode symmetric capacitor test. The results reveal that MWCNTs/PPy/rGO/NWF possesses a maximum specific capacitance (C_sc) of about 319 F g^?1 while PPy/rGO/NWF has a C_sc of about 277.8 F g^?1 at the scan rate of 1 mV s^?1 and that optimum MWCNTs/PPy/rGO/NWF retains 94.5% of initial C_sc after 1000 cycles at scan rate of 80 mV s^?1 which is higher than PPy/rGO/NWF (83.4%). Further analysis reveals that the addition of MWCNTs can increase the charger accumulation at the outer and inner of the composites, which is favorable to improve the stability and the rapid charge‐discharge capacity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41023.     

Conversion of pencil graphite to graphene/polypyrrole nanofiber composite electrodes and its doping effect on the supercapacitive properties

Graphene platelets were synthesized from pencil flake graphite and commercial graphite by chemical method. The chemical method involved modified Hummer's method to synthesize graphene oxide (GO) and the use of hydrazine monohydrate to reduce GO to reduced graphene oxide (rGO). rGO were further reduced using rapid microwave treatment in presence of little amount of hydrazine monohydrate to graphene platelets. Chemically modified graphene/polypyrrole (PPy) nanofiber composites were prepared by in situ anodic electropolymerization of pyrrole monomer in the presence of graphene on stainless steel substrate. The morphology, composition, and electronic structure of the composites together with PPy fibers, graphene oxide (GO), rGO, and graphene were characterized using X‐ray diffraction (XRD), laser‐Raman, and scanning electron microscopic (SEM) methods. From SEM, it was observed that chemically modified graphene formed as a uniform nanocomposite with the PPy fibers absorbed on the graphene surface and/or filled between the graphene sheets. Such uniform structure together with the observed high conductivities afforded high specific capacitance and good cycling stability during the charge–discharge process when used as supercapacitor electrodes. A specific capacitance of supercapacitor was as high as 304 F g^?1 at a current density of 2 mA cm^?1 was achieved over a PPy‐doped graphene composite. POLYM. ENG. SCI., 55:2118–2126, 2015. © 2014 Society of Plastics Engineers     

One-step electrosynthesis of MnO2/rGO nanocomposite and its enhanced electrochemical performance

We present a facile one-step electrochemical approach to generate MnO₂/rGO nanocomposite from a mixture of Mn₃O₄ and graphene oxide (GO). The electrochemical conversion of Mn₃O₄ into MnO₂ through potential cycling is expedited in the presence of GO while the GO is reduced into reduced graphene oxide (rGO). The MnO₂ nanoparticles are evenly distributed on the rGO nanosheets and act as the spacer to prevent rGO nanosheets from restacking. This unique structure provides high electroactive surface area (1173?m² g^?1) that improves ions diffusion within the MnO₂/rGO structure. As a result, the MnO₂/rGO nanocomposite exhibits high specific capacitance of 473?F?g^?1 at 0.25?A?g^?1, which is remarkably higher (3 times) than the Mn₃O₄/GO prior conversion. In addition, the electrosynthesized nanocomposite shows higher conductivity and excellent potential cycling stability of 95% at 2000 cycles.     

Supercapacitor device performances of polycarbazole/graphene and polycarbazole/nanoclay/graphene nanocomposites

In this study, graphene oxide (GO) is chemically reacted with sodium borohydride (NaBH₄) to form reduced graphene oxide (rGO). rGO, polycarbazole (PCz)/rGO and PCz/nanoclay/rGO materials were obtained by chemical polymerisation method. These three materials were characterised by Fourier-transform infra-red spectroscopy-attenuated transmission reflectance, scanning electron microscopy, energy-dispersive X-ray analysis, cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy. The PCz/nanoclay/rGO nanocomposite shows significantly improved capacitance (C_sp?=?187.78?F?g^?1) compared to that of PCz/rGO (C_sp?=?74.18?F?g^?1) and rGO (C_sp?=?20.78?F?g^?1) at the scan rate of 10?mV?s^?1 by CV method. The supercapacitor device performance results show high power density (P?=?1057.81?W?kg^?1) and energy density (E?=?1.7?Wh?kg^?1) obtained from Ragone plot for PCz/nanoclay/rGO material. Stability tests were also examined by the CV method for 1000 cycles.     

Synthesis of rGO/nanoclay/PVK nanocomposites,electrochemical performances of supercapacitors

ABSTRACT

In this study, graphene oxide (GO) was chemically reacted with sodium borohydride (NaBH₄) to form reduced graphene oxide (rGO). rGO, Montmorillonite nanoclay, and polyvinylcarbazole (PVK) were used to form a ternary nanocomposite via chemical reaction. These nanocomposite qualities were described via scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy-attenuated transmission reflectance (FTIR-ATR). In addition, these materials were used in supercapacitor device as an active material to test electrochemical performances via cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The rGO/nanoclay/PVK nanocomposite shows significantly improved specific capacitance (C_sp = 168.64 Fg^?1) compared to that of rGO (C_sp = 63.26 Fg^?1) at the scan rate of 10 mVs^?1 by CV method. The enhanced capacitance results in high power density (P = 5522.6 Wkg^?1) and energy density (E = 28.84 Whkg^?1) capabilities of the rGO/nanoclay/PVK nanocomposite material. The addition of nanoclay and PVK increased the specific capacitance of rGO material due to a dopant effect for supercapacitor studies. Ragone plots were drawn to observe energy and power density of supercapacitor devices. The C_sp of rGO/nanoclay/PVK nanocomposite has only 86.4% of initial capacitance for charge/discharge performances obtained by CV method for 5000 cycles.     

Synthesis of polythiophene/graphene oxide composites by interfacial polymerization and evaluation of their electrical and electrochemical properties

We report a new method for the synthesis of polythiophene (PTh)/graphene oxide (GO) nanocomposites by interfacial polymerization. Polymerization occurred at the interface of two immiscible solvents, i.e. n‐hexane containing thiophene and nitromethane containing GO and an initiator. Characterizations were done using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and electrochemical and electrical conductivity measurements. Spectroscopic analyses showed successful incorporation of GO in the PTh matrix. Morphological analysis revealed good dispersion of GO sheets in the polymer matrix. The PTh/GO composites showed marked improvements in thermal stability and electrical conductivity (2.7 × 10^?4 S cm^?1) compared to pure PTh. The composites exhibited excellent electrochemical reversibility compared to pure PTh at a scan rate of 0.1 V s^?1. The composites were stable even up to 100 electrochemical cycles, indicating good cycle performance. The specific capacitance of the composites was calculated using cyclic voltammetry and was found to be 99 F g^?1. © 2014 Society of Chemical Industry     

Self‐assembled polypyrrole film by interfacial polymerization for supercapacitor applications

A facile interfacial synthesis strategy is proposed to synthesize self‐assembled polypyrrole (PPy) free‐standing films for electrochemical capacitors with the assistance of surfactants. The chemical structure of the obtained samples is characterized by Fourier transform infrared. The morphologies of the samples are studied by scanning electron microscope. The results show that the prepared PPy films own highly porous structures using Tween80 as a surfactant, while the synthesized PPy films have vesicular structures by adding Span80 as a surfactant. Furthermore, lowering polymerization temperature makes PPy films have smaller and more pores or vesicles. The PPy films prepared at 0°C with Tween80 as a surfactant possess a high specific capacitance of 261 F g^?1 at 25 mV s^?1 as well as retain 75% of the initial specific capacitance value after 1000 cycles. The good electrochemical properties can be attributed to the highly porous structural advantage of the PPy films caused by Tween80. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41615.     

Fabrication of Tiron‐doped polypyrrole/MWCNT composite electrodes with high mass loading and enhanced performance for supercapacitors

In this study, the aromatic sulfonate compound Tiron with high charge to mass ratio is used as an anionic dopant for synthesis of polypyrrole (PPy). The fabricated PPy is investigated for electrochemical supercapacitor (ES) application. Testing results show that Tiron allows reduced PPy agglomeration, smaller particle size and improved charge storage properties of PPy. High capacitance and improved capacitive retention at high scan rates are achieved by the fabrication of PPy/multiwalled carbon nanotube (MWCNT) composite electrode using safranin (SAF) as a co‐dispersant. The Tiron‐doped PPy electrode shows the highest capacitance of 7.8 F cm^?2 with a mass of 27 mg cm^?2. The Tiron‐doped PPy/MWCNT composite electrode shows good capacitance retention with a capacitance of 1.0 F cm^?2 at the scan rate of 100 mV s^?1. Symmetric supercapacitor cells are fabricated using PPy based active materials. An energy density of 0.36 mWh cm^?2 is achieved. The energy/power density and capacitance retention of the Tiron‐doped PPy/MWCNT ES is significantly improved in comparison with PPy‐based ES, prepared without Tiron or MWCNT. The Tiron‐doped PPy/MWCNT symmetric supercapacitor presents good cycling performance with 91.4% capacitance retention after 1000 charge–discharge cycles. The PPy/MWCNT composites, prepared using Tiron and SAF co‐dispersant, are promising electrodes for ES. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42376.     

Electrochemically synthesized graphene/polypyrrole composites and their use in supercapacitor

Composite films consisting of polypyrrole (PPy) and graphene oxide (GO) were electrochemically synthesized by electrooxidation of 0.1 M pyrrole in aqueous solution containing appropriate amounts of GO. Simultaneous chronoamperometric growth profiles and frequency changes on a quartz crystal microbalance showed that the anionic GO was incorporated in the growing GO/PPy composite to maintain its electrical neutrality. Subsequently, the GO was reduced electrochemically to form a reduced GO/PPy (RGO/PPy) composite by cyclic voltammetry. Specific capacitances estimated from galvanostatic discharge curves in 1 M H₂SO₄ at a current density of 1 A g^?1 indicated that values for the RGO/PPy composite were larger than those of a pristine PPy film and the GO/PPy composite. In the case of 6 mg mL^?1 GO for the preparation of GO/PPy, a high specific capacitance of 424 F g^?1 obtained at the electrochemically prepared RGO/PPy composite indicated its potential for use as an electrode material for supercapacitors.     

Potentiostatically deposited polypyrrole/graphene decorated nano-manganese oxide ternary film for supercapacitors

A simple method based on potentiostatic polymerization was developed for the preparation of ternary manganese oxide-based nanocomposite films. The ternary nanocomposites, which were characterized using x-ray diffraction spectroscopy and x-ray photoelectron spectroscopy, showed that the manganese oxide within the film consisted of MnO₂ and Mn₂O₃. Electrochemical measurements showed that the ternary nanocomposite electrode exhibited high specific capacitance (up to 320.6 F/g), which was attributed to the morphology of a polypyrrole/graphene/manganese-oxide (PPy/GR/MnO_x) ternary nanocomposite. The experimental approach maximized the pseudocapacitive contribution from redox-active manganese oxide (MnO_x) and polypyrrole (PPy), as well as the electrochemical double layer capacitive (EDLC) characteristic from graphene (GR) sheets. Long cyclic measurements indicated that the specific capacitance of the ternary nanocomposite film could retain 93% of its initial value over 1000 charge/discharge cycles, in the potential range of −0.2 to 0.7 V versus silver/silver chloride electrode (Ag/AgCl).     

Cauliflower-like poly(3,4-ethylenedioxythipohene)/nanocrystalline cellulose/manganese oxide ternary nanocomposite for supercapacitor

A cauliflower-like ternary nanocomposite of poly(3,4-ethylenedioxythipohene)/nanocrystalline cellulose/manganese oxide (PEDOT/NCC/MnO₂) was synthesized using one-step electropolymerization technique. The effect of manganese (Mn) concentration on the supercapacitive performance was investigated. The structural and morphology studies were conducted using field emission scanning electron microscope, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction. The morphology of ternary nanocomposite at an optimized concentration of Mn resembles the cauliflower-like structure. The two-electrode electrochemical analysis of a ternary nanocomposite PEDOT/NCC/MnO₂ exhibited a higher specific capacitance of 144.69 F/g at 25 mV/s in 1.0 M potassium chloride compared to PEDOT/NCC(63.57 F/g). PEDOT/NCC/MnO₂ ternary nanocomposite was able to deliver a specific power of 494.9 W/kg and 10.3 Wh/kg of specific energy at 1 A g⁻¹ and retained 83% of initial capacitance after 2,000 cycles. These promising results from the incorporation of Mn displayed great prospective in developing PEDOT/NCC/MnO₂ as an electrode material for supercapacitor.     

Interfacial synthesis of polypyrrole/graphene composites and investigation of their optical,electrical and electrochemical properties

We report the development of a novel route for the synthesis of polypyrrole/graphene (PPy/GR) composites by liquid ? liquid interfacial polymerization, where GR and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, X‐ray diffraction, thermogravimetric analysis, electrochemical and electrical conductivity measurements. Structural analysis reveals a uniform dispersion of GR sheets in the PPy matrix. The composites showed noticeable improvement in thermal stability and electrical conductivity (8.45 S cm^?1) and excellent electrochemical reversibility in comparison with pure PPy. A specific capacitance of 260 F g^?1 at a current density of 100 mA g^?1 was achieved for the composite during the charge–discharge process. © 2013 Society of Chemical Industry     

Preparation of the flexible polypyrrole/polypropylene composite fibrous film for electrochemical capacitor

Polypyrrole (PPy)/polypropylene fibrous membrane (PPF) composite materials with different PPy contents are prepared through in situ chemical oxidation polymerization in the pyrrole atmosphere at room temperature by dissolving the FeCl₃·6H₂O in methanol and acetonitrile as oxidant. The morphology of the composite is examined by scanning electron microscope (SEM), the conductivities of the composites are measured by convenient four‐probe method, and the properties of the capacitor cells assembled by the obtained PPy/PPF are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) measurements. The results show that the morphology, conductivity, and the capacitor property of the composite are influenced strongly by the solvent of the oxidant. The capacitor assembled by the PPy/PPF prepared by using acetonitrile as the solvent for FeCl₃^.6H₂O can adapt for quick charge/discharge, and exhibit the highest capacitance of about 72.5 F g^?1 when the PPy content is about 8.0%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Preparation and electrochemistry of nanostructured PPy/graphite nanosheets/rare earth ions composites for supercapacitor

Highly conductive PPy/graphite nanosheets/rare earth ions (PPy/nanoG/RE³⁺) composites were prepared via in‐situ polymerization with p‐toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The microstructures of nanoG and PPy/nanoG/RE³⁺ were characterized by the SEM and TEM examinations. It was found that nanoG and PPy nanospheres formed the uniform composite with the PPy nanospheres embedded on the nanoG surface and/or filled between the nanoG. The effects of nanoG and RE³⁺ on the electrical conductivity and electrochemical performance of the composites were investigated. The results showed that the nanoG and RE³⁺ as the filler had effect on the conductivity and electrochemical performance of PPy/nanoG/RE³⁺ composites, which played an important role in forming a conducting network in PPy matrix. A specific capacitance of as high as 175 F/g at a current density of 1 A/g was achieved over the PPy/nanoG/Gd³⁺ composite. The capacitance of the PPy/nanoG/Gd³⁺ composite decreased only 5.1% after 800 charging/discharging cycles at a current density of 1 A/g. POLYM. ENG. SCI., 54:2731–2738, 2014. © 2013 Society of Plastics Engineers     

Enhanced performance by polyaniline/tailored carbon nanotubes composite as supercapacitor electrode material

Polyaniline/tailored carbon nanotubes composite (PANI/TCN) synthesized via situ polymerization of aniline monomer in the presence of tailored carbon nanotubes (TCN) is reported as electrode material for supercapacitors. The morphology, structure, and thermostability of the composite were characterized by scanning electron microscope, Fourier transform infrared, and thermogravimetric analysis. The electrochemical property of the resulting material was systematically studied using cyclic voltammetry and galvanostatic charge–discharge. The results show that the short rod‐like PANI dispersed well in the TCN with three‐dimensional network structure. The as‐prepared composite shows high specific capacitance and good cycling stability. A specific capacitance of 373.5 F g^?1 at a current density of 0.5 A g^?1 was achieved, which is much higher than that of pure PANI (324 F g^?1). Meanwhile, the composite retains 61.7% capacity after 1000 cycles at a scan rate of 50 mV s^?1. The enhanced specific capacitance and capacity retention indicates the potential of composite as a promising supercapacitor electrode material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39971.     

In situ doping of PANI nanocomposites by gold nanoparticles for high‐performance electrochemical energy storage

Polyaniline (PANI) in situ doped with gold nanoparticles (Au/PANI) is synthesized by oxidative polymerization as electrode material for supercapacitor. The morphologies and structure of the obtained products are characterized by transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy; and electrochemical behaviors were measured by electrochemical workstation. The results show that the nanocomposites of Au/PANI are fabricated with gold nanoparticles (nano‐Au) dispersed well in PANI bulk; and specific capacitance (SC) and rate ability of Au/PANI are improved compared to the pristine PANI due to the introduction of nano‐Au. With nano‐Au content increasing, SC first increase and then decrease and the maximum SC of Au/PANI nanocomposite is up to 462 F g^?1 with the nano‐Au content of 1.64 wt %. Finally, both asymmetric and symmetric supercapacitor devices are assembled, exhibiting high energy densities of 8.95 and 4.17 Wh kg^?1, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45309.     

High performance electrospun PVdF‐HFP/SiO2 nanocomposite membrane electrolyte for Li‐ion capacitors

Electrospun poly[(vinylidene fluoride)‐co ‐hexafluoropropylene]/silica (PVdF‐HFP/SiO₂) nanocomposite polymer membranes (esCPMs) were prepared by incorporating different weight percentages of SiO₂ nanoparticles onto electrospun PVdF‐HFP by electrospinning technique. The surface morphology of electrospun PVdF‐HFP nanocomposite membranes was characterized by scanning electron microscopy. The effect of SiO₂ nanoparticles incorporation onto electrospun PVdF‐HFP polymer membranes (esPMs) has been studied by XRD, DSC, TGA, and tensile analysis. The electrospun PVdF‐HFP/SiO₂ based nanocomposite membrane electrolytes (esCPMEs) were prepared by soaking the corresponding esCPMs into 1 M LiPF₆ in EC:DMC (1:1 vol/vol %). The ionic conductivity of the esCPMEs was studied by AC‐impedance studies and it was found that the incorporation of SiO₂ nanoparticles into PVdF‐HFP membrane has improved the ionic conductivity from 1.320 × 10^?3 S cm^?1 to 2.259 × 10^?3 S cm^?1. The electrochemical stability of the esCPME was studied by linear sweep voltammetry studies and it was found to be 2.87 V. Finally, a prototype LiCo_0.2Mn_1.8O₄//C Li‐ion capacitor (LIC) cell was fabricated with esCPME, which delivered a discharge capacitance of 128 F g^?1 at the current density of 1 A g^?1 and retained 86% of its discharge capacitance even after 10,000 cycles. These results demonstrated that the esCPMEs could be used as promising polymer membrane electrolyte for LICs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45177.     

The unique morphology role of thorn surface in determining electrochemical performance of polyaniline nano‐fibers via one‐step method

Polyaniline nano‐fibers with thorn surface morphology (T‐PANI) were synthesized by one‐step polymerization with adding additional aniline at later stage of chemical oxidation synthesis. In order to investigate the morphology role in determining electrochemical performance, the nano‐fibers PANI without thorn (PANI) was synthesized by the same polymerization process but at different time to add additional aniline. Material structures were characterized by field emission scanning electron microscope and Brunauer‐Emmett‐Teller method, and electrochemical performance was tested through cyclic voltammograms, galvanostatic charge‐discharge and electrochemical impedance spectroscopy. The data showed that the specific capacitance of T‐PANI was 443 F g^?1 at 5 mA cm^?2, which was much more than that of PANI (338 F g^?1 at 5 mA cm^?2). The solution resistance, charge transfer resistance, and diffuse resistance of T‐PANI were also lower than these of PANI. The results indicate that the thorn surface structure plays an important role in determining the electrochemical performance of polyaniline, which attribute to the improvements in pore size, pore distribution, special surface area, and conductivity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42266.     

Effect of dopant and oxidant on the electrochemical properties of polyaniline/graphite nanoplate composites

Optimizing the synthesis parameters of polyaniline/graphite nanoplate (PANI/GNP) composite is essential to the final electrochemical performance. Herein, the electrochemical properties of PANI/GNP composites, prepared by in situ chemical polymerization using varying amounts of different oxidants, with or without the addition of 4‐dodecylbenzenesulfonic acid (DBSA) as dopant, were investigated. Cyclic voltammetric results suggested that a stoichiometric amount of the oxidant iron chloride (FeCl₃) was beneficial to the electrochemical properties of the composites. The use of ammonium persulfate (APS) instead of FeCl₃ as oxidant largely increased the actual PANI content, conductivity and specific capacitance of the PANI/GNP composites. The dopant DBSA increased the conductivity of the PANI/GNP composites but did not show a positive effect on the electrochemical behavior. The cyclic voltammograms of the PANI/GNP composites indicated that the pseudocapacitance of PANI contributes more than the electrical double‐layer capacitance of GNP to the capacitance of the composites, while the presence of GNP plays an essential role in the rate capability of the composites. In this study, PANI/GNP (1:1) composite synthesized with an APS to aniline molar ratio of 1 showed a balanced combination of high specific capacitance (180.5 F g^?1 at 20 mV s^?1) and good rate capability (78% retention at 100 mV s^?1). © 2018 Society of Chemical Industry