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     

导电聚合物复合材料作为超级电容器电极材料

本文综述了基于导电聚合物的复合材料(导电聚合物/碳材料、导电聚合物/金属氧化物材料、导电聚合物/碳材料l金属氧化物材料)作为电极材料在超级电容器中的应用进展,指出将导电聚合物与碳材料或金属氧化物复合,双电层电容与法拉第准电容结合,有机材料与无机材料结合,是超级电容器电极材料研究的重要发展方向.     

MnO2基超级电容器电极材料

超级电容器作为一种新型的储能装置,具有长寿命、高功率等特点,在诸多领域内有广泛的应用前景。在影响超级电容器性能的所有因素中,电极材料的性能起着决定性的作用。二氧化锰(MnO₂)具有原料易得,价格低廉,来源广泛,环境友好等优点。综述了MnO₂超级电容器电极材料的储能机理,纳米MnO₂的微观结构与电化学特性之间的关系,并从纳米MnO₂的制备及其综合改性角度,综述其合成、掺杂改性、复合方法在MnO₂基电极材料的新进展,指出了MnO₂基超级电容器电极材料的主要研究方向。     

Synthesis of La-doped NiO nanofibers and their electrochemical properties as electrode for supercapacitors

La-doped NiO nanofibers were synthesized by the electrospinning method. The X-ray diffraction (XRD) pattern showed that La doping does not change the crystal structure up to the doping ratio of La/Ni=1.5%. Electrochemical properties of La-doped NiO nanofibers were investigated using cyclic voltammetry and galvanostatic charge/discharge. The results showed that the La doping can enhance the charge/discharge specific capacitance and electrochemical stability of the NiO nanofibers. Especially, the sample with doping ratio of La/Ni=1.5% could reach a discharge specific capacitance of 94.85 F g⁻¹ at a constant current density of 5 mA cm⁻².     

Encapsulation of manganese oxides nanocrystals in electrospun carbon nanofibers as free-standing electrode for supercapacitors

Flexible composites with manganese oxides (MnO_x) nanocrystals encapsulated in electropun carbon nanofibers were successfully fabricated via a simple and practical combination of electrospinning and carbonization process. The as-formed MnO_x/carbon nanofibers composites have a rough surface with MnO_x nanoparticles well embedded in the carbon nanofibers backbones. When used as electrodes for supercapacitor, the resulting MnO_x/carbon nanofiber composites exhibit good electrochemical performance with a specific capacitance of 174.8 F g⁻¹ at 2 mV s⁻¹ in 0.5 M Na₂SO₄ electrolyte, a good rate capability at high current density and long-term cycling stability. It is expected that such freestanding composites could be promising electrodes for high-performance supercapacitors.     

超级电容器碳基材料研究的进展

超级电容器是一种介于传统电容器和蓄电池之间的储能装置,其以功率密度大,充电速度快,工作温度范围宽,循环使用寿命长和绿色环保等优点,被世界各国广泛关注。通过对超级电容器新型碳电极材料的最新研究进展进行介绍,展望了超级电容器的发展前景,认为超级电容器将不仅对全球性能源问题有着重大突破,还将会带来巨大的经济效益。     

聚苯胺/壳聚糖超级电容器电极复合材料的制备及表征

采用冷冻干燥后管式炉碳化制备壳聚糖电极材料,经KOH活化法活化后通过氧化还原聚合法制备聚苯胺(PANI)/壳聚糖电极材料,运用循环伏安、交流阻抗、充放电等测试聚苯胺/壳聚糖电极的电化学性能。结果表明,聚苯胺/壳聚糖电极材料表现出良好的电容性能和稳定的电化学性能,比电容129.6 F/g,循环充放电500次,比电容保持率90.8%。     

Carbon molecular sieves as model active electrode materials in supercapacitors

Various microporous carbon molecular sieves are studied as active electrode material for supercapacitors in order to clarify the controversy about the accessibility of the electrolyte to the micropores. Cyclic voltammetry experiments were performed in electrolytes with different ion size. The results showed a clear ion sieving effect when the porosity of the carbon was similar to that of the ions of the electrolyte. Impedance spectroscopy was also useful to evidence diffusion restrictions of the ions into the pores. The results obtained in this study clearly demonstrate that in aqueous media very narrow micropores (0.5 nm) are still capable of forming the electrical double layer. Therefore, the majority of microporous carbons, with wider porosity, are perfectly suitable as active electrode materials for supercapacitors when aqueous electrolytes are used.     

聚苯胺/壳聚糖超级电容器电极复合材料的制备及表征

采用冷冻干燥后管式炉碳化制备壳聚糖电极材料,经KOH活化法活化后通过氧化还原聚合法制备聚苯胺(PANI)/壳聚糖电极材料,运用循环伏安、交流阻抗、充放电等测试聚苯胺/壳聚糖电极的电化学性能。结果表明,聚苯胺/壳聚糖电极材料表现出良好的电容性能和稳定的电化学性能,比电容129.6 F/g,循环充放电500次,比电容保持率90.8%。     

木质素基材料在混合型超级电容器电极材料中的研究进展

木质素是一种多酚聚合物,具有丰富的芳香类官能团和含氧官能团,且在碳化后形成的多孔碳材料易于转化为石墨化碳层,从而形成局部高导电区域,是制备超级电容器的优质前体,故将木质素用于混合型超级电容器逐渐成为研究热点之一。本文综述了近年来木质素碳材料在混合型超级电容器电极材料中的应用,重点分析了木质素在其中的作用,将其总结为3类进行介绍,包括木质素/多孔炭（石墨烯、碳纳米管）型、木质素/金属化合物（金属氧化物、硫化物、氢氧化物）型和木质素/导电聚合物（聚苯胺、聚吡咯、聚噻吩）型。此外,还介绍了木质素基混合型超级电容器在柔性超级电容器中的应用。最后,总结了木质素基材料应用在混合超级电容器中的优势和挑战。     

氧化物型超级电容器电极材料的研究进展

氧化物型电极材料可以发生可逆的氧化还原反应从而具有较大的赝电容,其比容量远远大于活性炭材料的双电层电容,而且使用寿命长,维护简单,具有广阔的应用前景。主要论述了超级电容器用氧化物电极材料(RuO_2、MnO_2、NiO和Co_3O_4等)的储能原理、制备和性能的研究现状。     

柔性固态非对称超级电容器电极材料的研究进展

综述了柔性固态非对称超级电容器关键元器件和材料的研究现状,重点介绍了柔性固态非对称超级电容器体系的材料选择与性能改善方面的研究进展,其中包括碳材料/过渡金属化合物材料和过渡金属氧化物/过渡金属氧化物材料等。同时还综合分析了选择不同材料体系的柔性固态非对称超级电容器结构与性能,并对该领域的发展趋势进行了展望。     

Enhancing the performance of polypyrrole composites as electrode materials for supercapacitors by carbon nanotubes additives

In the framework of this study, a facile method to obtain polypyrrole (PPy)/carbon nanotubes composites is presented. Chemical polymerization of PPy directly on the carbon nanotubes allows to obtain a homogenous distribution of the polymer. A low amount of carbon additive, varying from 1.5 to 5.5 wt %, is applied in order to prevent the decrease of capacitance value due to the presence of a low-capacitance component and, at the same time, to protect the electrode material from mechanical changes during cycling electrical measurements. The electrochemical properties, such as capacitance, its retention at different current loads, cycling stability, or self-discharge, are discussed. Improvement of electrochemical performances of the synthesized materials is observed mostly during cyclic stability measurements and at high current regimes. The obtained results confirm that the addition of only 3% of carbon nanotubes provides the best electrochemical performances as electrode materials for supercapacitor application. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48867.     

导电聚合物基超级电容器电极材料研究进展

导电聚合物是一类重要的超级电容器电极材料。本文介绍了导电聚合物基电极材料的工作原理、优势及不足。在此基础上,介绍了目前为克服该类电极材料性能不足所做的相关研究工作,回顾了该类材料的研究现状。最后提出今后该类材料的研究重点是改善导电聚合物微观形貌、构建三维导电聚合物基电极复合材料及对该类材料制备工艺的优化等方面。     

Solvothermal synthesis of porous MnCo2O4.5 spindle-like microstructures as high-performance electrode materials for supercapacitors

This study presents the facile preparation of novel MnCo₂O_4.5 microspindles (MSs) for the first time through a rapid solvothermal method combined with subsequent calcination of the precursor at 450 °C for 4 h in air. The MnCo₂O_4.5 MSs have an average length of 4–5 µm and diameter of 2–4 µm, respectively, achieving a specific surface area as high as 83.3 m² g⁻¹. In addition, the size and morphology of the MnCo₂O_4.5 microstructures could be easily tuned by some parameters including reaction time, volume ratio of ethanol to water, and dosage of urea. The electrochemical performance was further evaluated in three-electrode system, detailed electrochemical characterizations revealed that such MnCo₂O_4.5 MSs exhibited both high specific capacitance of 343 F g⁻¹ at a current density of 0.5 A g⁻¹ and excellent cycling performance of 81.3% capacitance retention after 5000 cycles at a current density of 4 A g⁻¹ in 2 M of KOH electrolyte, which made it a potential electrode material for an advanced supercapacitor. Furthermore, the present synthetic method is simple and can be extended to the synthesis of other electrode materials based on transition metal oxides.     

Copper substituted nickel ferrite nanoparticles anchored onto the graphene sheets as electrode materials for supercapacitors fabrication

Nickel ferrites with high theoretical capacitance value as compared to the other metal oxides have been applied as electrode material for energy storage devices i.e. batteries and supercapacitors. High tendency towards aggregation and less specific surface area make the metal oxides poor candidate for electrochemical applications. Therefore, the improvements in the electrochemical properties of nickel ferrites (NiFe₂O₄) are required. Here, we report the synthesis of graphene nano-sheets decorated with spherical copper substituted nickel ferrite nanoparticles for supercapacitors electrode fabrication. The copper substituted and unsubstituted NiFe₂O₄ nanoparticles were prepared via wet chemical co-precipitation route. Reduced graphene oxide (rGO) was prepared via well-known Hummer's method. After structural characterization of both ferrite (Ni_1-xCu_xFe₂O₄) nanoparticles and rGO, the ferrite particles were decorated onto the graphene sheets to obtain Ni_1-xCu_xFe₂O₄@rGO nanocomposites. The confirmation of preparation of these nanocomposites was confirmed by scanning electron microscopy (SEM). The electrochemical measurements of nanoparticles and their nanocomposites (Ni_0.9Cu_0.1Fe₂O₄@rGO) confirmed that the nanocomposites due to highly conductive nature and relatively high surface area showed better capacitive behavior as compared to bare nanoparticles. This enhanced electrochemical energy storage properties of nanocomposites were attributed to the graphene and also supported by electrical (I-V) measurements. The cyclic stability experiments results showed ~65% capacitance retention after 1000 cycles. However this retention was enhanced from 65% to 75% for the copper substituted nanoparticles (Ni_0.9Cu_0.1Fe₂O₄) and 65–85% for graphene based composites. All this data suggest that these nanoparticles and their composites can be utilized for supercapacitors electrodes fabrication.     

Chemical synthesis of Co and Mn co-doped NiO nanocrystalline materials as high-performance electrode materials for potential application in supercapacitors

Co and Mn co-doped with NiO nanostructued materials, such as, Ni_0.95Co_0.01Mn_0.04O_1−δ, Ni_0.95Co_0.04Mn_0.01O_1−δ and Ni_0.95Co_0.025Mn_0.025O_1−δ were synthesized by chemical synthesis route and studied for potential application as electrode materials for supercapacitors. The phase structure of the materials was characterized by X-ray diffraction (XRD) and the crystallographic parameters were found out and reported. FTIR (Fourier Transform Infrared) spectroscopy revealed the presence of M–O bond in the compounds. The particle size of the materials was found to be in the range of 291.5–336.5 nm. The morphological phenomenon of the materials was studied by scanning electron microscopy (SEM) and the particles were found to be in spherical shape with average grain size of 14–28 nm. EDAX analysis confirmed the presence of appropriate levels of elements in the samples. The in-depth morphological characteristics were also studied by HR-TEM (High Resolution Tunneling Electron Microscopy). Cyclic voltammetry, chronopotentiometry and electrochemical impedance measurements were applied in an aqueous electrolyte (6 mol L⁻¹ KOH) to investigate the electrochemical performance of the Co and Mn co-doped NiO nanostructured electrode materials. The results indicate that the doping level of Co and Mn in NiO had a significant role in revealing the capacitive behaviors of the materials. Among the three electrode materials studied, Ni_0.95Co_0.025Mn_0.025O_1−δ electrode material shows a maximum specific capacitance of 673.33 F g⁻¹ at a current density of 0.5 A g⁻¹. The electrochemical characteristics of blank graphite sheet were studied and compared with the performance of Co/Mn co-doped NiO based electrode materials. Also, Ni_0.95Co_0.025Mn_0.025O_1−δ has resulted in a degradation level of 4.76% only after 1000 continuous cycles, which shows its excellent electrochemical performance, indicating a kind of potential candidate for supercapacitors.     

Electrochemical fabrication of polyaniline/MnO2/graphite felt as free‐standing,flexible electrode for supercapacitors

Polyaniline/MnO₂/graphite felt (PMGF) composite, which can be used as a novel free‐standing, flexible electrode for supercapacitors, was fabricated via a facile electrochemical method. Polyaniline/graphite felt (PANI/GF) electrode was prepared by electropolymerization of PANI onto the GF. Subsequently, manganese dioxide (MnO₂) was electrodeposited on the surface of the PANI/GF electrode to prepare PMGF electrode. The microstructure and morphology of the as‐prepared samples were characterized by Fourier transform infrared spectra, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Specific surface area was examined using N₂ adsorption/desorption test. Cyclic voltammogram, chronopotentiometry techniques and electrochemical impedance spectroscopy were introduced to investigate the electrochemical performance of the composites. The PMGF electrode exhibited specific capacitance as high as about 630 F g⁻¹ at the current density of 0.5 A g⁻¹, which is much higher than that of PANI/MnO₂ composites reported previously. The high specific capacitance of PMGF may be attributed to the fact that the porous GF is a good conductive matrix for the dispersion of PANI/MnO₂ and it can facilitate easy access of electrolytes to the electrode, which results in enhancement of the electrochemical performance of the composite. Moreover, the specific capacitance of PMGF is much larger than that of MnO₂/GF (MGF), which may be ascribed to the participant of PANI, which contributes additional pseudocapacitance and electron transport path. POLYM. COMPOS., 34:819–824, 2013. © 2013 Society of Plastics Engineers     

Ideal asymmetric supercapacitors consisting of polyaniline nanofibers and graphene nanosheets with proper complementary potential windows

Polyaniline (PANI) nanofibers are synthesized via a chemical method of rapid mixing for the application of asymmetric supercapacitors. The diameter and aspect ratio of PANI nanofibers is found to be controllable by varying the aniline/oxidant concentration ratio. The ideal capacitive responses of PANI nanofibers between 0.2 and 0.7 V (vs. Ag/AgCl) in concentrated acidic media are demonstrated by cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) analyses coupled with a schematic equivalent-circuit model. The morphologies and textures of nanofibers are examined by scanning electron microscopic (SEM), transmission electron microscopic (TEM) and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopic analyses. An aqueous asymmetric supercapacitor, consisting of a PANI nanofiber cathode and a graphene anode, with proper complementary potential windows is demonstrated in this work, which shows the device energy and power densities of 4.86 Wh kg⁻¹ and 8.75 kW kg⁻¹, respectively.