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Shielding Effectiveness of Composites Containing Flaky Inclusions

高电压技术 2013年第8期39卷 1995-1999页

作者： WANG Qingguo QU Zhaoming WANG Yilong Institute of Electrostatic & Electromagnetic Protection Mechanical Engineering College Shijiazhuang 050003 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

To investigate the quantitative relationship between the electromagnetic-shielding property of composites and the distribution of inclusions, a scheme for predicting the shielding effectiveness of composites containing variously-distributed flaky inclusions is proposed. The scheme is based on equivalent parameters of homogeneous comparison materials and the plane-wave shielding theory. It leads to expli- cit formulas for the shielding effectiveness of multi-layered composites in terms of microstructural parameters that characterize the shape, distribution and orientation of the inclusions. For single layer composite that contains random and aligned flaky silver-coated carbonyl-iron particles with fractions of different volume, the predicted shielding effectiveness agrees well with the experimental data. As for composites containing aligned flaky particles,the shielding effectiveness obtained by the proposed scheme and experiment data is higher than that the random case, e.g. about 20 dB higher at 750 MHz. The proposed scheme is a straightforward method for optimizing future composite de- signs.

关键词：多层复合材料屏蔽效能夹杂物片状微观结构参数实验数据羰基铁粒子电磁屏蔽

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Electrochemical Nanowire Devices for Energy Storage

Electrochemical Nanowire Devices for Energy Storage

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Liqiang Mai Chaojiang Niu Xiaocong Tian Xu Xu Qinyou An Qiulong Wei Yunlong Zhao State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key Laboratory Wuhan University of Technology

One-dimensional nanomaterialshave attracted significant attention for a wide range of energy-related applications due to such unique advantages as short Li-ion insertion/extraction distance, facile strain relaxation upon electrochemical cycling, enhanced electron transport, and very large surface to volume ratio. We designed the single nanowire electrode devices as a unique platform for in situ probing the direct relationship between electrical transport, structure, and electrochemical properties of the single nanowire electrode to understand intrinsic reason of capacity fading. It demonstrates that during the electrochemical reaction conductivity of the nanowire electrode decreased, which limits the cycle life of the devices. Then, the prelithiation and Langmuir-Blodgett technique have been used to improve the cycling stability of nanowire electrode. Recently, we have synthesized SVO/PANI triaxial nanowires and fabricated hierarchical MnMoO 4 /CoMoO 4 heterostructured nanowires by combining "oriented attachment" and "self-assembly". The asymmetric supercapacitors based on the hierarchical heterostructured nanowires showed a high specific capacitance and good reversibility with a cycling efficiency of 98% after 1,000 cycles. Furthermore, we fabricated Li-air battery based on hierarchical mesoporous LSCO nanowires and nonaqueous electrolytes, which exhibits ultrahigh capacity over 11000 mAh g –1 , with the improvement of one order of magnitude than LSCO nanoparticles. We also designed and synthesized novel cucumber-like MnO 2 nanoparticles-enriched V 2 O 5 /PEDOT coaxial nanowires by layer-by-layer assembly with enhanced electrochemical performance. Recently we designed a nanoscroll buffered hybrid nanostructural VO 2 (B) composed of nanobelts and nanowires with greatly improved cycle life and rate capability. It is expected that our study may extend effective and helpful methods in directions that will solve the challenge of property degradation in energy storage an

关键词： nanowire devices, lithium batteries, energy storage

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Nanosphere Cathode Materials with Three-dimensional Continuous Electron Pathways for Long-life and High-rate Lithium Storage

Nanosphere Cathode Materials with Three-dimensional Continuo...

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Yifan Dong Shuo Li Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key Laboratory Wuhan University of Technology

Lithium-ion batteries （LIBs） are receiving considerable attention as storage devices in the renewable and sustainable energy developments. However, facile fabrication of long-life and high-rate cathode materials for LIBs is required to facilitate practical application. Among the candidate materials for high power LIBs, sodium super ionic conductor （NASICON） structured polyanion-based orthophosphate Li 3 V 2 （PO 4 ） 3 exhibits high energy and power density, and has been regarded as a prospective alternative cathode material in high power facilities such as electric vehicles, hybrid electric vehicles, and other power-supply equipment. Nevertheless, Li 3 V 2 （PO 4 ） 3 still faces some challenges such as low electronic conductivity and capacity fading during cycling. Here we propose a rationally controllable synthesis of highly crystalline Li 3 V 2 （PO 4 ） 3 nanospheres with a uniform carbon coating layer to restrain structure degradation during cycling. Additionally, acetylene black was used as the reducing agent and the template for particle growth, as well as a three-dimensional conductive and flexible network to provide a continuous electron pathway in the electrode. The uniform carbon layer and the conductive carbon network have a synergetic effect to enhance not only the cycling stability but also rate performance of Li 3 V 2 （PO 4 ） 3 in the application for LIBs. The as-prepared cathode material has a discharge capacity of 142 mA h g -1 at 1 C rate, approaching its theoretical value （150 mA h g -1 ）, and can even be cycled at a rate as high as 30 C without capacity fading. After 1000 cycles at a rate of 5 C, the as-prepared material has capacity retention of up to 83%, and can also tolerate 5000 cycles with a considerable capacity, demonstrating excellent cycling stability. Our work shows that this material has great potential for high-energy and high-power energy storage applications, and this rational method can be applied to synthesizing high-performance catho

关键词： lithium batteries energy storage long-life high-rate

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The study of artificial xenon arc lamp ageing on E-glass/vinyl ester composites

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Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica 2013年第SUPPL.期30卷 33-39页

作者： Ni, Aiqing Zhang, Lifeng Ji, Yundong Wang, Jihui State Key Laboratory of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Department of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China

The effects of artificial xenon arc lamp ageing on E-glass/vinyl ester composite were investigated. The mechanical properties of the composite are investigated by static mechanical tests, the storage and loss moduli, Tg, the peak of tanδ by DMA, the peak location and peak intensity by FTIR for pure resin and the composite, and fracture development and the relationship between fracture density and fatigue stress level by SEM, respectively. It is found out that the most significant ageing factor is ultraviolet radiation, and that the introduction of glass fiber will accelerate the crosslink and degradation of resin.

关键词： Glass fibers

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Nanoscroll Buffered Hybrid Nanostructure for Long-Life and High-Rate Lithium Storage

Nanoscroll Buffered Hybrid Nanostructure for Long-Life and H...

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Qiulong Wei Qinyou An Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key Laboratory Wuhan University of Technology

Rechargeable lithium batteries have been widely used for consumer electronics and are desirable for the development of hybrid electric vehicles and electric vehicles, due to their high energy density and good environment compatibility. The enhanced electrochemical performance of electrodes depends on not only the material intrinsic characteristics, but also the designed morphologies. One-dimensional （1D） nanostructures can offer large surface area and efficient electron transport pathway to achieving high capacity. As a functional nanostructure, nanoscroll with open ends/edges could provide easy radial expansion by interlayer sliding to buffer the swelling during lithiation/delithiation. Herein, we report a nanoscroll buffered hybrid nanostructural VO 2 （B）（HNS） composed of nanobelts and nanowires with greatly improved cycle life and rate capability. It is found that this unique HNS with buffered section provides facile strain relaxation to accommodate the volume variations during lithiation/delithiation, which greatly enhance the structural stability and cyclability. Further, the interior of nanoscrolls and the interconnected voids between the hybrid nanostructures could shorten the lithium ion diffusion pathway for fast charge/discharge. As a result, the HNS cathode exhibits long-life performance with capacity retention over 82% after 1,000 cycles at C （1,000 mA g -1 ）, and high rate up to ～20 C （2,000 mA g -1 ）. This unique HNS can be applied to the next-generation high-performance batteries for portable electronics and large-scale energy storage devices. Constructing the nanoscroll buffered hybrid nanostructure described in this paper is a facile and effective method to enhance the electrochemical performance of other electrode materials.

关键词： lithium batteries, nanoscrolls, nanowires, hybrid nanostructure, nano energy

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Facile and Scalable synthesis of Graphene by Direct Transformation of Amorphous Carbide

Facile and Scalable Synthesis of Graphene by Direct Transfor...

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IUPAC 9th International Conference on Novel Materials and their synthesis(NMS-IX) & 23rd International Symposium on Fine Chemistry and Functional Polymers(FCFP-XXIII)(IUPAC第九届新型材料和合成国际会议暨第23届国际精细化工和功能聚合物研讨会)

作者： Tao Peng Shichun Mu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

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POROUS GRAPHENE ELECTRODES FOR PEM FUEL CELLS

POROUS GRAPHENE ELECTRODES FOR PEM FUEL CELLS

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第五届世界氢能技术大会(WHTC2013)

作者： Kun Cheng Daping He Tao Peng Haifeng Lv Mu Pan Shichun Mu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070China

As an air-pollution-free and high efficient power generating device,proton exchange membrane fuel cell (PEMFC) has attracted a wide *** of the key components of PEMFC is catalyst,during while the support materials pla... 详细信息

关键词： Proton exchange membrane fuel cell graphene pore mass diffusion catalyst

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Gas Sensing Properties of Ultralong MoO3 Nanobelts for Ethanol Gas

Gas Sensing Properties of Ultralong MoO3 Nanobelts for Ethan...

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Shuang Yang Yueli Liu Wei Jin Wen Chen Tingqiang Yang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Materials Science and Engineering Wuhan University of Technology

As a layered-structure semiconductor material with wide band gap, MoO 3 has been considered to be a promising candidate for application in gas sensor. Recently, gas sensor based on MoO 3 have been found to have a response towards various gases such as H 2 S, NO 2 , NH 3 , trimethylamine, formaldehyde and H 2 in the temperature range of 300–600 °C. Although MoO 3 films and nanorods are not sensitive to ethanol gas, it is found that the ultralong MoO 3 nanobelts have a good sensitivity and selectivity to ethanol gas in our works. In the present work, the ultralong MoO 3 nanobelts are prepared by hydrothermal method using a molybdenum organic salt precursor. The nanobelts are flexible with an average length of 200-300μm and width of 500nm, which won’t be broken even after bended or distorted. The nanobelts are characterized by using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Raman spectra. Gas sensor based on ultralong and flexibility MoO 3 nanobelts is then fabricated. The sensor shows a good sensitivity towards ethanol gas, while almost no response towards other reducing gases, such as ammonia and formaldehyde in the temperature range of 220–380 ℃, the detection limit to ethanol gas may reach to 5ppm at the temperature of 380℃, which indicates that this kind of sensor has a promising future for ethanol detection. In conclusion, a gas sensor has been fabricated based on ultralong and flexibility MoO 3 nanobelts, which are prepared by hydrothermal method using a molybdenum organic salt precursor, and it is sensitive to ethanol gas. The reason for the good sensitivity to ethanol may be due to the large specific surface area, axial electron transfer and the non-stoichiometry of MoO 3 nanobelts.

关键词： Ultralong MoO 3 Nanobelts, Hydrothermal method, Gas Sensing Property, Ethanol gas

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Influcence of the TiO2 and Cu2S nanowire arrays served as the photo-anodes and photo-cathodes on the efficiency of quantum dots sensitized solar cells

Influcence of the TiO2 and Cu2S nanowire arrays served as th...

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Zhuoyin Peng Yueli Liu Yinghan Zhao Keqiang Chen Yuqing Cheng Chen Wen State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Materials Science and Engineering Wuhan University of Technology

Quantum dots sensitized solar cells (QDSSCs) have been attracted much attention as the next generation photovoltaic devices, due to the size-effect, high absorption coefficient and multiple excitation generation of quantum dots (QDs). Recently, Mn-CdS/CdSe and CuInS 2 /Mn-CdS sensitized solar cells has been obtained. However, the performance of the solar cells is still limited by the transfer barrier of the photo-induced electrons from nanoparticles. Nowadays, the single crystalline nanorods, nanowires and nanotubes arrays structure have been widely prepared to improve the electron transfer. In order to effectively enhance the efficiency, the nanowire structure is expected to be employed in both photo-anodes and counter electrodes for QDSSCs fabrication. In this work, Cu 2 S nanowire arrays are prepared by the solution method, which are employed to the photo-cathodes of solar cells, meanwhile, single crystalline anatase TiO 2 nanowires arrays are prepared by hydrothermal method and then be transferred to FTO substrate as the photo-anodes. CuInS 2 and Mn-CdS QDs are deposited on TiO 2 nanowire arrays films by using linking assembly method and chemical bath deposition. The structure, morphology and optical properties have been characterized by XRD, SEM, UV-Vis spectra. Under a solar illumination, the photovoltaic efficiency of this double-side nanowire structure based solar cells are obviously enhanced from 3.3% to 4.1%. In summary, the CuInS 2 /Mn-CdS QDs sensitized solar cells by using TiO 2 and Cu 2 S nanowire arrays as the photo-anodes and photo-cathodes have been fabricated. It is found that the photovoltaic performance of these QDSSCs is obviously enhanced comparing to the nanoparticles based solar cells. The reason is originated from that fact that the better electron transfer and injection from the one-dimensional nanowire arrays structure.

关键词： Anatase TiO 2 nanowire arrays, CuInS 2 /Mn-CdS quantum dots co-sensitized solar cells, Cu 2 S nanowire arrays counter electrodes, efficiency enhancement

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Single-nanowire solar cells based on the surface-passivated CdS/Ag2S core-shell heterostructures

Single-nanowire solar cells based on the surface-passivated ...

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International Conference on Nanoscience & technology,China 2013(ChinaNANO 2013)

作者： Keqiang Chen Yueli Liu Zhuoyin Peng Yuqing Cheng Wen Chen State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Materials Science and Engineering Wuhan University of Technology

Single-nanowire solar cells have been considered to be the promising candidates as the nanoelectronical and flexibledevices, as they possess large surface-to-volume ratio and short minority carrier’stransferring path. Recently, there is some kinds of heterostructures are used to fabricated single-nanowire solar cells, such as CdS/Cu 2 S, CuInSe 2 /CdS. Among them, cadmium sulfide （CdS） and silver sulfide （Ag 2 S） have been attracted much attention for excellentoptoelectronic property, and surface-passivated is an important process to improve the efficiency. Till now, there is few works focused on the influence of the surface-passivated layer on the photovoltaicefficiency of the CdS/Ag 2 S core-shell single-nanowires solar cells. Herein, CdS nanowires were synthesized via vapor liquid solid（VLS） method, which is used as the core structure. To obtain CdS/Ag 2 S core-shell structure, cation exchange was carried out through mixing CdS solution with AgNO 3 solution.A ZnS passivation layer with the thickness of 0nm was achieved by chemical bath deposition （CBD） process. The single CdS/Ag 2 S core-shell nanowires were separated individually on the regular Au pattern fabricated by the photolithography technique, and then two ends of the nanowires were well contacted with Au electrodes by using the electron beam lithography. X-raydiffraction, SEM, X-ray spectroscopy and TEM techniques were used to character the microstructure, morphology and combining chemical state. The fabricated single-nanowire solar cells were irradiated under AM 1.5G illumination, an efficiency improvement from 1.8% to 2.4%was achieved due to the preventing charge carriers from reaching the surface by surface-passivated layer. In conclusion, CdS/Ag 2 Sheterostructures had been successfully prepared by cation exchange method, achieving an efficiency enhancement by forming the surface-passivated single-nanowire solar cells.

关键词： CdS/Ag 2 Sheterostructure cation exchange single-nanowire solar cells surface-passivated photovoltaicefficiency.

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