Determination of the specific capacitance of conducting polymer/nanotubes composite electrodes using different cell configurations

Composite materials containing 20 wt.% of multiwalled carbon nanotubes (MWNTs) and 80 wt.% of chemically formed conducting polymers (ECP) as polyaniline (PANI) and polypyrrole (PPy) have been prepared and used for supercapacitor electrodes. The well conducting properties of MWNTs and their available mesoporosity allow a good charge propagation in the composites. Moreover, due to the good resiliency of MWNTs, an excellent stability of the supercapacitor electrodes is observed. It has been shown that the capacitance values for the composites strongly depend on the cell construction. In the case of three electrode cells, extremely high values can be found from 250 to 1100 F/g, however in the two electrode cell much smaller specific capacitance values of 190 F/g for PPy/MWNTs and 360 F/g for PANI/MWNTs have been measured. It highlights the fact that only two-electrode cells allow a good estimation of materials performance in electrochemical capacitors. The applied voltage was found to be the key factor influencing the specific capacitance of nanocomposites. For operating each electrode in its optimal potential range, asymmetric capacitors have been built with PPy/MWNTs as negative and PANI/MWNTs as positive electrodes giving capacitance values of 320 F/g per electrode material.     

Preparation and characterization of composites of polyaniline nanorods and multiwalled carbon nanotubes coated with polyaniline

Composites of polyaniline (PANI) nanorods and multiwalled carbon nanotubes (MWNTs) coated with PANI were prepared by in situ polymerization with perchloric acid as a dopant. Transmission electron microscopy images showed that the coexisting composites of PANI nanorods and MWNTs coated with PANI were formed at low MWNT contents. The interaction between MWNTs and PANI was proved by Fourier transform infrared and ultraviolet–visible spectra. The electrical conductivity of a dedoped PANI/MWNT composite with a 16.3 wt % concentration of MWNTs reached 3.0 × 10^?3 S/cm, which was 6 orders of magnitude higher than that of dedoped PANInanorods. The results also showed that coexisting composites of PANI nanorods and MWNTs coated with PANI had high electrochemical activity and good cyclic stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Covalently-grafted polyaniline on graphene oxide sheets for high performance electrochemical supercapacitors

A simple route to achieve covalently-grafted polyaniline (PANI)/graphene oxide (GO) nanocomposites has been developed. The synthesized composites showed a uniform hierarchical morphology of the PANI thin film and short rod-like nanostructures that had densely grown on the GO sheets, in contrast to the nonuniform morphology of noncovalently-grafted PANI/GO. Compared to pure PANI and noncovalently-grafted PANI/GO composites, the covalently-grafted PANI/GO composites possessed a much larger specific surface area and pore volume, which increased the accessible surface area for the redox reaction and allowed faster ion diffusion. This unique hierarchical morphology maximized the synergistic effect between PANI and GO, resulting in excellent electrochemical performance (capacitance 442 F/g of PANI/GO (6:1) vs. 226 F/g of pure PANI) and improved cycling stability (83% @ 2000 cycles of PANI/GO (6:1) vs. 54.3% @ 1000 cycles of pure PANI). The enhanced electrochemical performance demonstrates the advantage of the PANI/GO composites prepared via this covalent grafting method.     

Nano graphene porous/conductive polymer as a composite material for energy storage in supercapacitors

This research studies the improving effects of graphene porous (GP) on the supercapacitive performance of a polyaniline/graphene porous (PANI/GP) nanocomposite. GP nanosheets were synthesized via chemical vapor deposition, and PANI/GP was electrochemically composited through successive cyclic voltammetry. The samples were characterized by fast Fourier transform infrared (FTIR), x-ray diffraction (XRD), and scanning electron microscopy (SEM), and energy-dispersive x-ray spectrometry (EDS) techniques. Porous GP nanosheets were uniformly dispersed in the composite structure. Furthermore, the electrochemical performances of the synthesized samples were compared using galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Incorporating GP into the PANI significantly increased specific capacitance from 276 (in PANI) to 577 F/g (in PANI/GP). The electrochemical stability of electrodes was compared during 1000 successive charge/discharge cycles. After 1000 cycles, PANI/GP kept 90% of its initial capacitance, and only 25% of the charge storage capacitance of bare PANI remained.     

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     

PANI/煤基石墨烯宏观体复合材料的制备及其电化学性能

以太西无烟煤为原料,采用催化热处理、改良Hummers氧化等方法,制备煤基氧化石墨烯（CGO）,进而以CGO和聚苯胺（PANI）为前驱体,采用水热自组装法,制备得到PANI/石墨烯宏观体复合材料（3D-PCG）。采用FT-IR、XRD、Raman、SEM和TEM等技术,研究了材料的组成、结构和形貌,考察了3D-PCG的电化学性能。结果表明,PANI以纳米棒状形态均匀镶嵌在煤基石墨烯宏观体（3D-CG）的网状结构中;当PANI与CGO质量比为1：2时,3D-PCG的电化学性能优于PANI和3D-CG,其比电容可达663 F·g^-1。     

Preparation and electrochemical properties of polyaniline/reduced graphene oxide composites

Polyaniline (PANI)/reduced graphene oxide (rGO) composites were synthesized by in situ oxidative polymerization of aniline on reduced graphene sheets. Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy were used to characterize the composites. The results indicated PANI/rGO composites were produced and contained covalent bonds between the functional groups of PANI and rGO. A uniform coating of PANI on the rGO sheets had a synergistic effect on the properties of the composites. The electrochemical properties of the PANI/rGO composites produced using different feed ratios of aniline to rGO were studied. The results showed that the composites exhibited a maximum specific capacitance of 797.5 F/g at 0.5 A/g and minimum charge transfer resistance of 0.98 Ω when the feed ratio of aniline to rGO was 2:1. These values were superior to those of pure PANI and rGO. The composites also displayed excellent cycling stability, with specific capacitance retention of 92.43% after 1000 cycles. These stable structural composites show promise for the development of new supercapacitor applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46103.     

Preparation and electrochemical characterization of MnOOH nanowire–graphene oxide

MnOOH nanowire–graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 °C with MnO₂–graphene oxide composites which are synthesized by a redox reaction between KMnO₄ and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO₂ is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire–graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g⁻¹ at current density of 0.1 A g⁻¹. Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire–graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire–graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire–graphene oxide composites strongly depends on their morphology.     

Fabrication and electrochemical characterization of polyaniline nanorods modified with sulfonated carbon nanotubes for supercapacitor applications

The novel composites of sulfonated multi-walled carbon nanotubes (sMWCNTs) modified polyaniline (PANI) nanorods (PANI/sMWCNTs) were synthesized successfully by in situ oxidative polymerization method in the HClO₄ solution. FTIR and Raman spectra revealed the presence of π–π interaction between the PANI and the sulfonated carbon nanotubes and the formation of charge transfer composites. It was found that the specific capacitance of the PANI/sMWCNT composites was markedly influenced by their morphological structure and the content of PANI which was coated onto the sMWCNT. The specific capacitance of the PANI/sMWCNT composite exhibited a maximum value of 515.2 F g⁻¹ at the 76.4 wt% PANI. The charge–discharge tests showed the PANI/sMWCNT composites possessed a good cycling stability (below 10% capacity loss after 1000 cycles) compared to PANI nanorods.     

微孔炭/聚苯胺纳米线复合材料的制备及其电化学电容性能

纳米线型导电聚合物是一种具有良好应用前景的超级电容器电极材料,该文用简易的原位化学氧化法制备了微孔炭/聚苯胺纳米线(MC/PANI)复合材料,并以此复合材料为活性物质制备工作电极,在1 mol/L H2SO4中,通过循环伏安、交流阻抗和恒流充放电技术考察了其电化学电容性能,结果表明,在0.2 A/g的电流密度下,MC/PANI电极首次充放电比电容可达到329 F/g,高于PANI电极的259 F/g,且MC/PANI电极电荷传递电阻(Rct)小于MC和PANI,可见纳米线型PANI可加强电极材料的电化学性能。     

Fabrication of graphene/single wall carbon nanotubes/polyaniline composite gels as binder-free electrode materials

A three-dimensional (3D) graphene-based hydrogels system containing one-dimensional (1D) carbon material-single wall carbon nanotubes (SWCNTs) and pseudocapacitor material-polyaniline (PANI) was prepared by combination of cross-linking, reduced and in situ polymerization. The polyaniline nanoparticles were combined with the reduced graphene sheet by π-π conjugation. The as-perpared composite gels could be directly used as electrode materials without binders. Due to the synergistic effect between SWCNTs, graphene sheet and PANI, the graphene/single wall carbon nanotubes/polyaniline (GH/SWCNTs/PANI) composite gel shows the enhanced electrochemical performances. The resultant GH/SWCNTs/PANI gel electroactive material shows a gravimetric specific capacitance of 145.4 F/g at 0.5 A/g and has improved 45% compared with initial graphene hydrogel (GH) at the same current density. And it keeps high retention of 98.8% of the initial capacity after 10,00 charge/discharge cycles at high current density of 10 A/g. The great cycle stability achieved is fundamentally attributed to the support of graphene sheet and single wall carbon nanotubes, which favors stress distribution and charge transfer during the longtime charge/discharge process. The graphene-based hydrogels could be a potential applicant for high rate charge/discharge applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46948.     

Vertically oriented polyaniline‐graphene nanocomposite based on functionalized graphene for supercapacitor electrode

Polyaniline functionalized reduced graphene oxide (PORGO) is prepared by interfacial polymerization and then vertically oriented polyaniline‐graphene (PANI‐PORGO) nanocomposites based on PORGO are developed successfully by in situ polymerization. The morphology and structure are characterized by field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT‐IR), Raman spectra and X‐ray diffraction (XRD). The electrochemical tests indicate that the specific capacitance of PORGO and PANI‐PORGO is as high as 291 and 369 F/g, respectively, at the current density of 1 A/g. PANI—PORGO nanocomposite exhibits high electrochemical activity and enhanced cycle stability with a capacitance retention of 81.2% after 500 cycles at 10 A/g. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44808.     

聚苯胺/氧化石墨烯接枝复合材料的制备及电容性能研究

利用化学氧化法原位聚合制备了聚苯胺(PANI)/氧化石墨烯(GO)接枝复合材料。透射电子显微镜表明,PANI纳米颗粒均匀地分布在GO的表面;通过UV-vis光谱证实了GO和PANI之间存在着强烈的相互作用;充放电测试表明,PANI/GO纳米复合材料具有良好的电荷储存特性,最高比电容可达575 F/g。由于与GO之间的化学结合作用,PANI的充放电循环稳定性得到明显提高。     

微孔碳/聚苯胺纳米线复合材料的制备及其电化学电

：纳米线型导电聚合物是一种具有良好应用前景的电容器电极材料,本论文中,用简易的原位化学氧化法制备了微孔碳/聚苯胺纳米线(MC/PANI)复合材料,并以此复合材料为活性物质制备工作电极,在1 mol/L H2SO4中,通过循环伏安、交流阻抗和恒流充放电技术研究了其电化学电容性能,研究结果表明：在0.2 A/g的电流密度下,MC/PANI电极首次充放电比电容可达到329 F/g, 高于PANI电极的259 F/g,且MC/PANI电极电荷传递电阻（Rct）小于MC和PANI,可见纳米线型PANI可加强电极材料的电化学性能。     

不同方法制备聚苯胺/MoS_2复合材料及其电容性能

结合Li插层法制备的单层MoS2,分别采用溶液法和乳液法原位聚合制备了聚苯胺/MoS2复合材料。由FT-IR光谱对其结构进行表征,由电化学工作站测试其做电容器电极材料的电化学性能。结果表明,相同MoS2用量下,乳液法制备的聚苯胺/MoS2复合材料在0.8 A/g电流密度下的比电容为245 F/g,是溶液法聚苯胺/MoS2复合材料的3倍;充放电1000圈后的比电容保持率为82%,比溶液法聚苯胺/MoS2复合材料高11%,显示出更好的电容性能。     

Polyaniline/single-wall carbon nanotube (PANI/SWCNT) composites for high performance supercapacitors

PANI/SWCNT composites were prepared by electrochemical polymerisation of polyaniline onto SWCNTs and their capacitive performance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1 M H₂SO₄ electrolyte. The PANI/SWCNT composites single electrode showed much higher specific capacitance, specific energy and specific power than pure PANI and SWCNTs. The highest specific capacitance, specific power and specific energy values of 485 F/g, 228 W h/kg and 2250 W/kg were observed for 73 wt.% PANI deposited onto SWCNTs. PANI/SWCNT composites also showed long cyclic stability. Based upon the variations in the surface morphologies and specific capacitance of the composite, a mechanism is proposed to explain enhancement in the capacitive characteristics. The PANI/SWCNT composites have demonstrated the potential as excellent electrode materials for application in high performance supercapacitors.     

Synthesis of carbon-coated graphene electrodes and their electrochemical performance

In this work, C-graphene composed of core graphene and carbon shells was prepared to obtain a new type of carbon electrode materials. Carbon shells containing nitrogen groups were prepared by coating polyaniline (PANI) onto graphene by in situ polymerization and subsequent carbonization at 850 °C. After carbonization, the C-graphene contained 6.5% nitrogen and showed a 2D plate structure and crystallinity like that of pristine graphene. In addition, the C-graphene exhibited electrochemical performance superior to that of pristine graphene, and the highest specific capacitance (170 F/g) of the C-graphene was obtained at a scan rate of 0.1 A/g, as compared to 138 F/g for pristine graphene. This superior performance was attributed to the synergistic effect of porous carbon layer and the graphene and the pseudocapacitive effect by the nitrogen groups formed on the carbon electrode after carbonization.     

三维有序结构聚苯胺/石墨烯纳米复合材料的制备及其在超级电容器电极中应用

用硼氢化钠(NaBH_4)还原氧化石墨烯得到还原石墨烯(rGO)分散液,rGO分散液与苯胺在酸性条件下原位聚合得到高比表面积三维有序结构的聚苯胺/石墨烯纳米复合材料。由场发射扫描电镜(FESEM)、透射电镜(TEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对其表面形貌和结构进行表征。结果表明:复合材料的比表面积高达136.9 m~2/g,高于纯聚苯胺的比表面积(32.71 m~2/g);直径10~20 nm的聚苯胺纳米棒均匀地垂直生长在石墨烯表面。在0.5 A/g的电流密度下,复合材料比电容达到358 F/g,大于石墨烯和聚苯胺的比电容;当充放电电流密度由0.5 A/g增加到10 A/g时,电容保留率达74.3%,表现出增强的倍率性能;在10 A/g高电流密度下,经过500次的充放电循环后容量保持率达到83.7%。     

聚苯胺/活性炭复合材料的共价键构筑及电容性能

导电聚苯胺(PANI)与活性炭(AC)构筑复合电极材料是当前制备高性能超级电容器电极材料的热点研究方向。其关键点之一是制备出炭与PANI两种材料均匀分散、且具有相当牢固强度连接界面的复合材料。为此,以AC为基材,对其进行功能化处理后,将苯胺在其表面原位聚合,获得具有界面共价键连接的PANI/AC复合材料(PANI–c–AC)复合材料。通过扫描电子显微镜、元素分析、傅里叶变换红外光谱、X射线衍射仪及电化学工作站等测试并研究其结构与电容性能。结果表明,具有界面共价键连接的PANI–c–AC复合材料比电容值(393.3 F/g)最高,既优于单一AC(111.8 F/g)与PANI(296.2 F/g),也优于无共价键连接的PANI–AC复合材料(360.5 F/g)。     

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%。