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Peng X.,Kunming University of Science and Technology | Peng X.,National Engineering Laboratory of Vacuum Metallurgy | Peng X.,Tsinghua University | An J.,Tsinghua University | And 4 more authors.
ECS Journal of Solid State Science and Technology | Year: 2016

In this paper, we report a method for the further reduction of the low-cost graphene (LG) via hydroiodic acid to synthesize graphene hybrid with varying content of δ-MnO2 . Scanning electron microscope (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were implemented to characterize the surface and structural properties of the reduced graphene (LGHI ) and graphene-MnO2 composites (GM). It can be observed that the thickness of LGHI layers is about 10?200 nm and as-prepared GM composites have a uniform morphology possessing a honeycomb structure. XRD results indicate that MnO2 in the GM exists as a δ-crystallographic structure of low crystallinity. Cyclic voltammetry (CV) curves, galvanostatic charge/discharge (GDC) curves and electrochemical impedance spectroscopy (EIS) were utilized in a three-electrode system to systematically investigate the electrochemical performance of varying δ-MnO2 content materials. Results reveal that once the mass fraction of δ-MnO2 in GM reaches 93.1% (labeled GM-6), the specific maximum capacitance of GM was found to be 783 F/g, 496 F/g, 345 F/g and 210 F/g at a current density of 0.3 A/g, 1 A/g, 3 A/g and 10 A/g, respectively. Moreover, GM-6 maintains almost 94.5% of its original specific capacitance after 5000 continuous cycles of charge-discharge. These promising results demonstrate that GM-6 has great potential to be utilized as an electrode material for supercapacitor applications. © 2016 The Electrochemical Society. Source

Liang F.,Kunming University of Science and Technology | Liang F.,National Engineering Laboratory of Vacuum Metallurgy | Dai Y.-N.,Kunming University of Science and Technology | Dai Y.-N.,National Engineering Laboratory of Vacuum Metallurgy | And 2 more authors.
Chinese Journal of Inorganic Chemistry | Year: 2010

Porous structure LiFePO4/C was synthesized by using triblock copolymer P123 as template combined with the self-assembly method. The crystal structure and electrochemical performance of synthesized samples were characterized by XRD, SEM, Nitrogen adsorption-desorption test, and charge-discharge test. The structure and electrochemical performance of the samples synthesized at different calcination times were studied. Results showed that the porous structure LiFePO4/C sample prepared at 700°C for 12 h had the best electrochemical performance, the first discharge capacity was 151.27 mAh·g-1 at 0.1C rate, and its electrochemical performance was better than the LiFePO4/C sample without porous structure. Source

Sun H.-Y.,National Engineering Laboratory of Vacuum Metallurgy | Sun H.-Y.,Kunming University of Science and Technology | Ma W.-H.,National Engineering Laboratory of Vacuum Metallurgy | Ma W.-H.,Kunming University of Science and Technology | And 5 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2011

A dense and crack-free La0.9Sr0.1Ga0.8 Mg0.2O3-δ thin film has been prepared by RF magnetron sputtering method on porous LSCM7355 anode substrates. The film with the good apparent morphology and a thickness about 10 μm was obtained when the operating parameters fixed as follows: the sputtering power is 210 W, the temperature of substrates is 300°C, the sputtering pressure is 5 Pa and the sputtering time span is 12 h. The polycrystalline perovskite type structure was obtained after the film annealed at 1000°C for 2 h in air. Source

Xu B.,National Engineering Laboratory of Vacuum Metallurgy | Xu B.,Key Laboratory of Vacuum Metallurgy of Non Ferrous Metals of Yunnan Province | Xu B.,Kunming University of Science and Technology | Pei H.,National Engineering Laboratory of Vacuum Metallurgy | And 12 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2011

A novel technique was developed to extract Mg impurity from the Ni-laterite by carbothermic reduction in vacuum. The impacts of experimental conditions, including the temperature, ratio of laterite/carbon, and addition of CaF2 at 40 Pa, on Mg removal rate were studied. The phases of the slag, morphology and contents of the condensates in carbothermic reduction were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The Mg extraction was calculated with thermodynamics. The calculated and experimental results show that the newly-developed technique is capable of extracting Mg! from, and en-richening Ni in the Ni-laterite under optimized conditions. For example, at 1500°C for 90 min and nickel laterite: carbon is 100:42(wt), the Mg removal rate was up to 93.85%, and the Ni content increased from 1.18% to 3.24%, with high densities of FeSi and SiC in the slag. Besides, the purity of condensed hexagonal-structured Mg was over 94%(wt). Source

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