Multiwalled Carbon Nanotubes Filled with Transition Metal Oxides as Supercapacitor Materials (original) (raw)
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Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are briefly investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in specific capacitance (SC) value as high as 135 Fg -1. Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density. © 2012 World Scientific Publishing Company.
Nano Tailoring of MnO2 doped Multiwalled carbon nanotubes as electrode materials for supercapacitor
2017
1Research and Development Centre, Bharathiyar University, Coimbatore, Tamil nadu, India 2Department of Physics, Sethu Institute of Technology, Virudunagar, Tamil nadu, India ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract Manganese decorated Multiwalled carbon nanotubes(MCNT) were synthesized through a simple solvo thermal method. The surface morphology and structural analyses of the MnO2 doped MCNT were done using Transmission electron microscope (TEM), Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) methods. The compositions of the prepared samples were obtained using Energy dispersive spectroscopy (EDS). Morphological studies revealed that a three-dimensional hierarchy architecture built with a highly porous film of interconnected MnO2 found on MCNT surface. The XRD and EDS results revealed that the prepared samples are in pure form without any impu...
Fabrication and Supercapacitor Applications of Multiwall Carbon Nanotube Thin Films
C
Multiwalled carbon nanotubes (MWCNTs) are a one-dimensional nanomaterial with several desirable material properties, including high mechanical tensile modulus and strength, high electrical conductivity, and good thermal conductivity. A wide variety of techniques have been optimized to synthesize MWCNTs and to fabricate thin films of MWCNTs. These synthesis and fabrication methods vary based on precursor materials, process parameters, and physical and chemical principals, and have a strong influence on the properties of the nanotubes and films. Thus, the fabrication methods determine the performance of devices that can exploit the advantageous material properties of MWCNTs. Techniques for the fabrication of carbon nanotubes and carbon nanotube thin films are reviewed, followed by a discussion of the use of MWCNTs as an electrode material for electrochemical double-layer supercapacitors (EDLCs). EDLCs feature high power density, excellent reversibility and lifetime, and improved energ...
Lancet
Graphene nanosheets (GNs) dispersed with SnO2 nanoparticles loaded multiwalled carbon nanotubes (SnO2–MWCNTs) were investigated as electrode materials for supercapacitors. SnO2–MWCNTs were obtained by a chemical method followed by calcination. GNs/SnO2–MWCNTs nanocomposites were prepared by ultrasonication of the GNs and SnO2–MWCNTs. Electrochemical double layer capacitors were fabricated using the composite as the electrode material and aqueous KOH as the electrolyte. Electrochemical performance of the composite electrodes were compared to that of pure GNs electrodes and the results are discussed. Electrochemical measurements show that the maximum specific capacitance, power density and energy density obtained for supercapacitor using GNs/SnO2–MWCNTs nanocomposite electrodes were respectively 224 F g−1, 17.6 kW kg−1 and 31 Wh kg−1. The fabricated supercapacitor device exhibited excellent cycle life with ∼81% of the initial specific capacitance retained after 6000 cycles. The results suggest that the hybrid composite is a promising supercapacitor electrode material.► Graphene nanosheets (GNs) dispersed with SnO2 nanoparticles loaded multiwalled carbon nanotubes (SnO2–MWCNTs) as electrode materials for supercapacitors. ► A maximum specific capacitance of 224 F g−1, power density of 17.6 kW kg−1 and an energy density of 31 Wh kg−1. ► Excellent cycle life with ∼81–92% of the initial specific capacitance retained after 6000 cycles, depending on electrode type. ► Dispersion of SnO2–MWCNTs helps in the improvement of the capacitance properties of GNs. ► GNs/SnO2–MWCNTs is a promising supercapacitor electrode material for practical applications.
Characterization of CNTs and CNTs/MnO2 composite for supercapacitor application
2010
Manganese oxide (MnO 2) was deposited on multiwalled carbon nanotubes (MWCNTs) via electrochemical deposition technique. Morphological and structural characterizations were examined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman Spectroscopy. Cyclic voltammetry and Galvanostatic charge-discharge measurements were performed to study the electrochemical properties. 0.2 M Na 2 SO 4 was used as an electrolyte for both experiments. For the purpose of the comparison, CNTs with different morphologies and water plasma treatment times were produced and optimized according to their capacitance performance. Results show that vertically aligned CNTs have improved capacitive performance than random aligned ones and that water plasma treatment cleans the amorphous carbon between nanotubes and increase the capacitance of CNTs from 0.19 to 1 mFcm-2. Finally, addition of 2-3 nm MnO 2 layer on CNTs improve the capacitance significanltly from 1 to 4.5 mFcm-2 (465 Fg-1). Therefore, results demonstrate that MnO 2 /MWCNT composite is a promising material to use as an electrode in supercapacitors.
Applied Materials Today, 2017
Developments during the past decade, electrode materials have been tuned to the nanoscale and electrolytes have gained an active role enabling more efficient storage mechanism; hence increasing the performance of supercapacitors manifold. In porous carbon materials with sub-nanometer pores, the desolvation of the ions leads to surprisingly high capacitances. Oxide materials store charge by surface redox reactions which are the foremost to the pseudo capacitive effect. Understanding the physical mechanisms underlying charge storage in these materials is important for further development of supercapacitors. This brief overview focuses on the different types of recent developed (asymmetric, pseudo) supercapacitors, experimental strategies, fabrication procedure, and electrochemical properties based on nanomaterials which have been reported recently for their high-quality performance, the relevant quantitative modeling history and the future of supercapacitor research and development.
2011
We report the synthesis of graphene oxide/multi-walled carbon nanotube (MWCNT) composites employing an alternative and novel approach for possible application as supercapacitor materials in energy storage devices. Integrating these nanostructures resulted in a strong synergistic effect between the two materials consequently leading to a robust and superior hybrid material with higher capacitance compared to either graphene oxide or MWCNTs. Specific capacitances of 251, 85 and 60 F g À1 were obtained for graphene oxide-multi-walled carbon nanotubes, MWCNTs and graphene oxide, respectively, in a potential range from À0.1 to 0.5 V. Most importantly, a 120% increase in capacitance was observed with increasing cycle number at 20 mV s À1. The ease of synthesis and the exceptional electrochemical properties make the use of this nanostructure an attractive, alternative way of designing future supercapacitors in both conventional fields and new emerging areas.
Electrochimica Acta, 2009
Poor crystallined ␣-MnO 2 grown on multi-walled carbon nanotubes (MWCNTs) by reducing KMnO 4 in ethanol are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Telle (BET) surface area measurement, which indicate that MWCNTs are wrapped up by poor crystalline MnO 2 and BET areas of the composites maintain the same level of 200 m 2 g −1 as the content of MWCNTs in the range of 0-30%. The electrochemical performances of the MnO 2 /MWCNTs composites as electrode materials for supercapacitor are evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M Na 2 SO 4 solution. At a scan rate of 5 mV s −1 , rectangular shapes could only be observed for the composites with higher MWCNTs contents. The effect of additional conductive agent KS6 on the electrochemical behavior of the composites is also studied. With a fixed carbon content of 25% (MWCNTs included), MnO 2 with 20% MWCNTs and 5% KS6 has the highest specific capacitance, excellent cyclability and best rate capability, which gives the specific capacitance of 179 F g −1 at a scan rate of 5 mV s −1 , and remains 114.6 F g −1 at 100 mV s −1 .
Journal of Nanomaterials, 2015
We present grafting of polycarboxyphenyl polymer on the surface of multiwalled carbon nanotube (MWCNT) via a free radical polymerization and subsequent anchoring of the metal oxide nanoparticles for the evaluation of their potential applicability to supercapacitor electrodes. Here, metal oxide nanoparticles, Fe3O4and Sm2O3, were created after the oxidation of metal precursors Sm(NO3)3and FeCl2, respectively, and attached on the surface of polycarboxyphenyl-grafted MWCNT (P-CNT) in aqueous medium. This approach shows a potential for enhancing the dispersion of Fe3O4and Sm2O3nanoparticles on the wall of P-CNT. The structure and morphological characteristics of the purified MWCNT, P-CNT, and metal oxide-anchored polycarboxyphenyl-grafted MWCNT (MP-CNT) nanocomposites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The electrochemical performance of the purified MWCNT electrode, P-...