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1.
A homogeneous composite of MnO2/multi-wall carbon nanotubes (MnO2/MWCNTs) was rapidly and efficiently synthesized by a redox reaction of MnO4− and Mn2+ on the MWCNTs under ultrasonic irradiation. The structure and morphology of the obtained MnO2 and MnO2/MWCNTs composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. Electrochemical investigation indicated that the maximum specific capacitance of the MnO2/MWCNTs composite, measured by galvanostatic charge-discharge test, was 315 F g− 1, compared to the pristine MnO2 (192 F g− 1) and MWCNTs electrode (25 F g− 1), showing the synergistic effect of MWCNTs and MnO2. The homogeneous hybrid nanostructure and the good conductivity of MWCNTs were considered to be responsible for its preferable electrochemical performances. 相似文献
2.
En-Hui Liu Wen Li Jian Li Xiang-Yun Meng Rui Ding Song-Ting Tan 《Materials Research Bulletin》2009,44(5):1122-828
Nanostructured nickel-manganese oxides composite was prepared by the sol-gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO2 samples exhibit higher surface area of 130-190 m2 g−1. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO2. When the mass ratio of MnO2 and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO2 calculated from the cyclic voltammetry curves is 453 F g−1, for pure NiO and MnO2 are 209, 330 F g−1 in 6 mol L−1 KOH electrolyte and at scan rate of 10 mV s−1, respectively. The specific capacitance of NiO/MnO2 electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties. 相似文献
3.
Hausmannite Mn3O4 polyhedral nanocrystals have been successfully synthesized via a simple solution-based thermolysis route using a three-dimensional hydrogen-bonded polymer as precursor. The as-obtained product was characterized by means of powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Possible formation mechanism of polyhedral nanocrystals was proposed based on the role of organic ligand dissociation from the polymer precursor at elevated temperature. The electrochemical capacitance performance of Mn3O4 electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. A maximum specific capacitance of 178 F g−1 was obtained for the nanocrystals in a potential range from −0.1 to 0.8 V vs. SCE in a 0.5 M sodium sulfate solution at a current density of 0.2 A g−1. 相似文献
4.
Hongjun Yue 《Materials Letters》2008,62(19):3388-3390
Manganese oxide/carbon nanotubes (MO/CNTs) composite was prepared by hydrothermally reducing KMnO4 with CNTs, where the used CNTs are of dual role, i.e., they serve as reductant during reaction and the remaining CNTs act as conducting agent in the composite. This composite was characterized by X-ray diffraction and scanning electron microscopy techniques. In addition, the electrochemical performances of the composite were investigated, which suggested an excellent rate-capability of this material; e.g., it delivered a high discharge capacity as 131 mAh g− 1 at a high current density of 4 A g− 1 (20 C), and high capacity at low discharge current density, e.g., about 209 mAh g− 1 at 0.2 C rate. Therefore, such a MO/CNTs composite is promising in high power application of lithium battery and electrochemical capacitor. 相似文献
5.
Graphene nanosheets-poly(o-aminophenol) (POAP/GNS) nanocomposite was fabricated on a platinum surface by potential cycling. Voltammograms of the POAP/GNS/Pt electrode showed an excellent capacitive behavior accompanied with a redox transition with a mid-peak potential of 295 mV. The POAP/GNS nanocomposite displayed a specific capacitance as high as 281.1 F g−1 at 0.1 A g−1 which is almost three times higher than that of pure graphene. The specific energy and power of the nanocomposite material were 25.0 Wh kg−1 and 34.8 W kg−1, respectively. The nanocomposite retained more than 99% of the initial capacitance after 1200 charge/discharge cycles. 相似文献
6.
Manganese oxide/single-wall carbon nanotubes (MnO2/SWNT) composite was co-deposited by the potentiostatic method on a graphite slice. Morphological and structural performances for MnO2/SWNT composite were characterized by means of scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The wall surface of SWNT was wrapped by ramsdellite MnO2 nanoparticles to fabricate MnO2/SWNT coaxial nanotubes, which further interconnected other MnO2 particles to form the porous MnO2/SWNT composite. The electrochemical properties were examined by cyclic voltammograms, galvanostatic charge and discharge and electrochemical impedance spectrum. A high specific capacitance of 421 F g?1 was obtained for overall MnO2/SWNT composite electrode at the constant current density of 1 A g?1 in 3 mol L?1 KCl solution. 相似文献
7.
Jinhui Zhang Yanhui WangJianbing Zang Guoxiang XinHuiying Ji Yungang Yuan 《Materials Chemistry and Physics》2014
Multi-walled carbon nanotubes (MWNTs) were selectively etched in molten nitrate to produce short MWNTs (s-MWNTs). MnO2/s-MWNT nanocomposite was synthesized by a reduction of potassium permanganate under microwave irradiation. For comparative purpose, MnO2/MWNT nanocomposite was also synthesized and investigated for its physical and electrochemical performance. Uniform and conformal MnO2 coatings were more easily formed on the surfaces of individual s-MWNTs. MnO2/s-MWNT nanocomposite estimated by cyclic voltammetry (CV) in 0.5 M Na2SO4 aqueous solution had the specific capacitance as high as 392.1 F g−1 at 2 mV s−1. This value was more than 48.9% larger than MnO2/s-MWNT nanocomposite. In addition, MnO2/s-MWNT nanocomposite was also examined by repeating the CV test at a scan rate of 50 mV s−1, exhibiting an excellent cycling stability along with 99.2% specific capacitance retained after 1000 cycles. Therefore, MnO2/s-MWNT nanocomposite is a promising electrode material in the supercapacitors. 相似文献
8.
Yaohui WangIgor Zhitomirsky 《Materials Letters》2011,65(12):1759-1761
Cathodic electrodeposition method has been developed for the fabrication of Ag-doped MnO2 films from the KMnO4 aqueous solutions containing AgNO3 for the application in electrodes of electrochemical supercapacitors (ES). The films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV) and impedance spectroscopy. The Ag-doped MnO2 films showed improved capacitive behaviour and lower electrical resistance compared to pure MnO2 films. The highest specific capacitance (SC) of 770 F g− 1 was obtained at a scan rate of 2 mV s− 1 in the 0.5 M Na2SO4 electrolyte. 相似文献
9.
Ball-nanostructured MnO2/MWCNTs composite was successfully prepared by microwave irradiation. The surface morphology and structures of the composite were examined by scanning electron microscope and X-ray diffraction. Multi-walled carbon nanotubes play a role as sustainment to inhibit MnO2 nanoplates from collapsing into nanorods. The electrochemical studies indicated that the composite had ideal capacitive performance and high specific capacitances of 298 F g− 1, 213 F g− 1 and 198 F g− 1 at the current density of 2 mA·cm− 2, 10 mA·cm− 2 and 20 mA·cm− 2, respectively. The formation mechanism of nanostructured MnO2/MWCNTs and the electrochemical behaviour of composites were discussed in detail. 相似文献
10.
Mesoporous MnO2 samples with average pore-size in the range of 2–20 nm are synthesized in sonochemical method from KMnO4 by using a tri-block copolymer, namely, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) as a soft template as well as a reducing agent. The MnO2 samples are found to be poorly crystalline. On increasing the amplitude of sonication, a change in the morphology of MnO2 from nanoparticles to nanorods and also change in porosity are observed. A high BET surface area of 245 m2 g−1 is achieved for MnO2 sample. The MnO2 samples are subjected to electrochemical capacitance studies by cyclic voltammetry (CV) and galvanostatic charge–discharge cycling in 0.1 M aqueous Ca(NO3)2 electrolyte. A maximum specific capacitance (SC) of 265 F g−1 is obtained for the MnO2 sample synthesized in sonochemical method using an amplitude of 30 μm. The MnO2 samples also possess good electrochemical stability due to their favourable porous structure and high surface area. 相似文献
11.
Microporous carbon derived from polyaniline base as anode material for lithium ion secondary battery 总被引:1,自引:0,他引:1
Xiaoxia Xiang Zhengzheng Huang Haijie Shen Yingying Tian Chengyi Xiao Jingjing Yang Zhaohui Mao 《Materials Research Bulletin》2011,46(8):1266-393
Microporous carbon with large surface area was prepared from polyaniline base using K2CO3 as an activating agent. The physicochemical properties of the carbon were characterized by scanning electron microscope, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurement. The electrochemical properties of the microporous carbon as anode material in lithium ion secondary battery were evaluated. The first discharge capacity of the microporous carbon was 1108 mAh g−1, whose first charge capacity was 624 mAh g−1, with a coulombic efficiency of 56.3%. After 20 cycling tests, the microporous carbon retains a reversible capacity of 603 mAh g−1 at a current density of 100 mA g−1. These results clearly demonstrated the potential role of microporous carbon as anode for high capacity lithium ion secondary battery. 相似文献
12.
Nannan Xia Tianxiang Zhou Jingxing Chen Shanshan Mo Yingliang Liu 《Materials Research Bulletin》2011,46(5):687-691
An efficient and quick microwave method has been employed to prepare worm-like mesoporous carbon@Bi2O3 composites for the first time. As-prepared products have been characterized by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy and inductive coupled plasma atomic emission spectroscopy. The electrochemical measurement shows the worm-like mesoporous carbon@Bi2O3 composites exhibits excellent capacitance performance and the maximum specific capacitance reaches 386 F g−1, three times more than the pure worm-like mesoporous carbon. 相似文献
13.
Hongjuan Li Lingjuan Deng Gang Zhu Liping Kang Zong-Huai Liu 《Materials Science and Engineering: B》2012,177(1):8-13
Ni2+-Fe3+ layered double hydroxides (LDHs)/MnO2 layered nanocomposite has been fabricated by using both layer-by-layer self-assembly method and flocculated technology, based on electrostatic interaction of positively charged Ni2+-Fe3+ LDHs nanosheets and negatively charged MnO2 nanosheets. Ultraviolet-visible spectroscopy is used to probe the dynamic growth of the multilayer film, exhibiting progressive enhancement of optical absorption due to the assembly of Ni2+-Fe3+ LDHs nanosheets and MnO2 nanosheets. The assembled Ni2+-Fe3+ LDHs/MnO2 nanocomposite has been characterized by XRD, SEM and TEM. The electrochemical property of the synthesized Ni2+-Fe3+ LDHs/MnO2 layered nanocomposite has been studied using cyclic voltammetry in a mild aqueous electrolyte. The Ni2+-Fe3+ LDHs/MnO2 nanocomposite exhibits a relative good capacitive behavior in a neutral electrolyte system, and its initial capacitance value is 104 F g−1. 相似文献
14.
Chih-Ming Chuang Cheng-Wei Huang Hsisheng Teng Jyh-Ming Ting 《Composites Science and Technology》2012
A conventional hydrothermal deposition process is used to graft ruthenium oxide (RuO2) nanoparticles onto carbon nanofibers (CNFs). The obtained RuO2 nanoparticles have an average diameter of 2 nm and are homogenously distributed on the CNF surfaces. Supercapacitors are fabricated using the resulting RuO2 grafted CNFs nanocomposite as the electrodes. The existence of CNFs leads to reduced contact resistance among the RuO2 nanoparticles and provides a network for fast electron transport, which then contributes to enhanced electrochemical performance. The enhancement is proportional to the RuO2 content and can be as high as 638% at a high sweep rate of 200 mV s−1, at which a capacitance is 155 F g−1. Stability of the RuO2-grafted CNF capacitor is also demonstrated by subjecting the capacitor to a potential sweep at 500 mV s−1 for 1000 cycles. Furthermore, the RuO2 grafted CNF capacitor exhibits a very short relaxation time of 0.17 s, which is desirable for high rate charge and discharge. 相似文献
15.
Lamellar birnessite-type MnO2 materials were prepared by changing the pH of the initial reaction system via hydrothermal synthesis. The interlayer spacing of MnO2 with a layered structure increased gradually when the initial pH value varied from 12.43 to 2.81, while the MnO2, composed of α-MnO2 and γ-MnO2, had a rod-like structure at pH 0.63. Electrochemical studies indicated that the specific capacitance of birnessite-type MnO2 was much higher than that of rod-like MnO2 at high discharge current densities due to the lamellar structure with fast intercalation/deintercalation of protons and high utilization of MnO2. The initial specific capacitance of MnO2 prepared at pH 2.81 was 242.1 F g−1 at 2 mA cm−2 in 2 mol L−1 (NH4)2SO4 aqueous electrolyte. The capacitance increased by about 8.1% of initial capacitance after 200 cycles at a current density of 100 mA cm−2. 相似文献
16.
Preparation and electrochemical properties of multiwalled carbon nanotubes-nickel oxide porous composite for supercapacitors 总被引:1,自引:0,他引:1
Porous nickel oxide/multiwalled carbon nanotubes (NiO/MWNTs) composite material was synthesized using sodium dodecyl phenyl sulfate as a soft template and urea as hydrolysis-controlling agent. Scanning electron microscopy (SEM) results show that the as-prepared nickel oxide nanoflakes aggregate to form a submicron ball shape with a porous structure, and the MWNTs with entangled and cross-linked morphology are well dispersed in the porous nickel oxide. The composite shows an excellent cycle performance at a high current of 2 A g−1 and keeps a capacitance retention of about 89% over 200 charge/discharge cycles. A specific capacitance approximate to 206 F g−1 has been achieved with NiO/MWNTs (10 wt.%) in 2 M KOH electrolyte. The electrical conductivity and the active sites for redox reaction of nickel oxide are significantly improved due to the connection of nickel nanoflakes by the long entangled MWNTs. 相似文献
17.
Mechanically blended composite of nanosized TiO2 and carbon nanotubes (CNTs) was investigated as potential anode materials for Li-ion batteries. It was found that the TiO2/CNTs nanocomposite exhibits an improved cycling stability and higher reversible capacity than CNTs. The reversible capacity of the TiO2/CNTs composite reaches 168 mAh g− 1 at the first cycle and remains almost constant during long-term cycling. The electrochemical results show that the TiO2 nanoparticles in the composite not only restrain the formation of surface film, but also make a contribution to the overall reversible capacity. 相似文献
18.
Syed Mustansar Abbas Syed Tajammul Hussain Saqib Ali Nisar Ahmad Nisar Ali Saghir Abbas 《Journal of Materials Science》2013,48(16):5429-5436
Metal oxides are well-known potential alternatives to graphite as anode materials of lithium-ion batteries, and they can deliver much higher reversible capacities than graphite even at high current densities. In this study, hexagonal disk-shaped ZnO are synthesized by a facile solution reaction of ZnCl2 and its composite is prepared in the presence of carbon nanotubes (CNTs). The as prepared ZnO/CNT composite has been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fourier transform-infrared spectroscopy and Rutherford backscattering spectroscopy. Electrochemical characterization by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic discharge/charge tests demonstrate that the conversion reactions in ZnO and ZnO/CNT electrodes enable reversible capacity of 478 and 602 mAh g?1, respectively for up to 50 cycles. Our investigation highlights the importance of anchoring of small ZnO particles on CNTs for maximum utilization of electrochemically active ZnO and CNTs for energy storage application in lithium-ion batteries. 相似文献
19.
Han Chen Yifeng ChenWenqiang Gong Kaixiong XiangBin Sun Jianhua Liu 《Materials Letters》2011,65(3):559-561
LiFePO4/C composite with network connections of nano-carbon wires was successfully prepared by using polyvinyl alcohol as carbon source. The composite was characterized by X-ray diffraction and transmission electron microscopic, and its electrochemical performance was investigated by galvanostatic charge and discharge tests. The experimental results show that LiFePO4 grains are tightly connected by the network of nano-carbon wires. Moreover LiFePO4/C composite exhibits high capacity of 168 mAh g−1 applied 15 mA g−1 current density (C/10), excellent cyclic ability and rate capability. When 1500 mA g−1 current density (10C) was applied, the high discharge capacity of 129 mAh g−1 has been obtained at room temperature. 相似文献
20.
Huan Xu Zhongai HuAilian Lu Yingying HuLi Li Yuying YangZiyu Zhang Hongying Wu 《Materials Chemistry and Physics》2013
We report a one-step fabrication of α-iron oxyhydroxide/reduced graphene oxide (α-FeOOH/rGO) composites, in which the ferrous sulfate (FeSO4·7H2O) are used as the iron raw and reducing agent to grow goethite (α-FeOOH) and reduce graphite oxide (GO) to rGO in the same time. The morphology, composition and microstructure of the as-obtained samples are systematically characterized by thermogravimetric (TG) analysis, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and FT-IR. Moreover, their electrochemical properties are investigated using cyclic voltammetry and galvanostatic charge/discharge techniques. The specific capacitance of 452 F g−1 is obtained at a specific current of 1 A g−1 when the mass ratio of α-FeOOH to rGO is up to 80.3:19.7. In addition, the α-FeOOH/rGO composite electrodes exhibit the excellent rate capability (more than 79% retention at 10 A g−1 relative to 1 A g−1) and well cycling stability (13% capacitance decay after 1000 cycles). These results suggest the importance and great potential of α-FeOOH/rGO composites in the applications of high-performance energy-storage. 相似文献