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Power frequency AC voltage measurement based on double wound Rogowski coil

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High Voltage 2017年第2期2卷 129-135页

作者： Mohamed E.Ibrahim Amr M.Abd-Elhady High Voltage and Dielectric Materials Lab. Faculty of EngineeringMenoufia UniversityShebin El_Kom 32511Egypt

This study presents a technique for power frequency AC voltage measurement.The proposed technique utilises a capacitor having a low capacitance in addition to a double wound Rogowski coil.This technique depends on capacitor current measurement using the double wound Rogowski coil.The voltage across the capacitor that connected in parallel with the system at which AC voltage is intended to be measured is reconstructed.The proposed technique is experimentally evaluated by designing the measurement system and using a digital signal processing board for the reconstruction processes.Moreover,the experimental results based on Rogowski coil measurements are compared with those obtained from reference techniques.Finally,the obtained results validate the efficacy of the proposed technique in power frequency AC voltage measurement.

关键词： Rogowski double capacitance

Ultra-small amorphous MoS2 decorated reduced graphene oxide for supercapacitor application

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Journal of Materials Science & Technology 2020年第5期40卷 196-203页

作者： Poulami Hota Milon Miah Saptasree Bose Diptiman Dinda Uttam K.Ghorai Yan-Kuin Su Shyamal K.Saha Department of Materials Science Indian Association for the Cultivation of ScienceJadavpurKolkata700032India Department of Materials Science and Engineering Seoul National UniversitySeoul151-744Republic of Korea Department of Industrial Chemistry and Applied Chemistry Ramakrishna Mission Vidyamandira and Swami Vivekananda Research CenterBelur MathHowrah711202India Green Energy Technology Research Center Kun Shan UniversityTainanTaiwanChina

Amorphous materials have recently gained much attention as electrode materials in supercapacitor application due to the presence of larger amount active sites which can efficiently increase the storage capacity of the materials.Nano engineering is an elegant approach to fully utilize the advantages of the amorphous structure.Moreover,large surface area and high conductivity of reduced graphene oxide(RGO)can efficiently increase the storage capacity of the system.Exploiting this idea,in the present work,we have successfully synthesized amorphous MoS2 of two different sizes on reduced graphene oxide and thoroughly investigated the supercapacitor behavior of the system.The specific capacitance of the composite structures has been found to be largely increased with decreasing size of the amorphous nano particle.The specific capacitance of amorphous MoS2-RGO composite containing nearly 50 nm of MoS2 found to be 270 F/g whereas when the particle size is reduced to 5–7 nm,value of specific capacitance increases to 460 F/g.The large increase in specific capacitance with the tuning of the size of amorphous nano particle has been explained by the presence of a large number of active sulfur edges of ultra-small MoS2 nano structure along with the better charge transport which can effectively increase the storage capacity of the overall system.The retention in the capacitance of the material has been found to be 90%after 5000 cycles.

关键词： Supercapacitor Ultrasmall amorphous MoS2 nanoparticles Sulfur edge sites Reduced graphene oxide(RGO) Specific capacitance

3D Printing Engineered Multi-porous Cu Microelectrodes with In Situ Electro-Oxidation Growth of CuO Nanosheets for Long Cycle,High Capacity and Large Rate Supercapacitors

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Acta Metallurgica Sinica(English Letters) 2021年第1期34卷 85-97页

作者： Tao Liu Yuejiao Chen Libao Chen State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Developing excellent pseudocapacitive electrodes with long cycle,high areal capacity and large rate has been challenged.3 D printing is an additive manufacture technique that has been explored to construct microelectrodes of arbitrary geometries for high-energy–density supercapacitors.In comparison with conventional electrodes with uncontrollable geometries and architectures,3 D-printed electrodes possess unique advantage in geometrical shape,mechanical properties,surface area,especially in ion transport and charge transfer.Thus,a desirable 3 D electrode with ordered porous structures can be elaborately designed by 3 D printing technology for improving electrochemical capacitance and rate capability.In this work,a designed,monolithic and ordered multi-porous 3 D Cu conductive skeleton was manufactured through 3 D direct ink writing technique and coated with Cu O nanosheet arrays by an in situ electro-oxidation treatment.Benefiting from the highly ordered multiporous nature,the 3 D-structured skeleton can eff ectively enlarge the surface area,enhance the penetration of electrolyte and facilitate fast electron and ion transport.As a result,the 3 D-printed Cu deposited with electro-oxidation-generated CuO(3 DP Cu@Cu O)electrodes demonstrates an ultrahigh areal capacitance of 1.690 F cm^(-2)(38.79 F cm^(-3))at a large current density of 30 m A cm^(-2)(688.59 m A cm^(-3)),excellent lifespan of 88.20%capacitance retention after 10,000 cycles at 30 m A cm^(-2) and superior rate capability(94.31%retention,2-30 m A cm^(-2)).This design concept of 3 D printing multi-porous current collector with hierarchical active materials provides a novel way to build high-performance 3 D microelectrodes.

关键词： 3D printing Supercapacitor Microelectrode Copper oxide Multi-porous current High areal specific capacitance

Carbon and Nickel Oxide/Carbon Composites as Electrodes for Supercapacitors

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Journal of Materials Science & Technology 2012年第10期28卷 931-936页

作者： Liutauras Marcinauskas Zydrūnas Kavaliauskas Vitas Valinius Plasma Processing Laboratory Lithuanian Energy Institute Department of Physics Kaunas University of Technology

The carbon and nickel oxide/carbon composite electrodes were prepared by plasma jet and magnetron sput-tering techniques. The investigations were performed to evaluate the influence of the Ar/C2H2 ratio on the specific capacitance values of carbon and NiO/carbon electrodes. The obtained electrodes were investigated by scanning electron microscopy, Raman scattering spectroscopy （RS）, and X-ray diffraction techniques. The surface of the carbon electrodes became less porous and more homogenous with increasing Ar/C2H2. The RS results indicated that the fraction of the sp2 carbon sites increased with increasing Ar/C2H2 ratio. The increase of the Ar/C2H2 ratio increased the capacitance values from 0.73 up to 3.8 F/g. Meanwhile, after the deposition of the nickel oxide on the carbon, the capacitance increased ten and more times and varied in the range of 7.6-86.1 F/g.

关键词： Carbon Plasma Nickel oxide capacitance Supercapacitors

Urchin-like NiCo2S4 structures synthesized through a one-step solvothermal process for high-performance supercapacitors

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Particuology 2019年第4期17卷 66-73页

作者： Yan Hu Jie Zhang Di Wang Jiangbo Sun Li Zhang Yanjie Liu Shiqiu Gao Yanbin Cui State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Nickel cobalt sulfides (MCo2S4) have attracted considerable attention as electrode materials for supercapacitors. Herein, a sea-urchin-like NiCo2S4 material was synthesized through a one-step solvothermal process. Polyethylene glycol (PEG) 200 and thiourea were used as a shape-control age nt and sulfur source for in-s让u sulfuration, respectively. The urchin-like NiC02S4 was characterized by X-ray powder diffraction, scanning electron microscopy, Brunauer-Emmett-Teller surface area, and electrochemical measurements. The resulting NiCo2S4 with ion diffusion-favored structure demonstrated remarkable electrochemical characteristics for supercapacitor with a high specific capacitance (1334F/g at 0.5 A/g) and superior rate capability (78.1% of the original capacity from 0.5 to 20 A/g) in 6M KOH aqueous solution. Furthermore, an asymmetric supercapacitor was assembled using NiCo2S4 as a positive electrode and activated carb on (AC) as a n egative electrode. A NiCo2Sj/AC device exhibited a high energy density of 37.32 Wh/kg at a power density of 317.8 W/kg with capacity retention of 91.9% and up to 2000 charge/discharge cycles at 3 A/g. The results demonstrate that the sea-urchin-like NiCo2S4 has potential applications in supercapacitors.

关键词： NiCo2S4 PEG Asymmetric supercapacitor Urchin-like structure High specific capacitance

Facile synthesis of hierarchical Ni_(3)Se_(2) nanodendrite arrays for supercapacitors

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Journal of Materials Science & Technology 2020年第19期54卷 69-76页

作者： Licheng Zhao Ping Zhang Yanan Zhang Zhi Zhang Lei Yang Zhi-Gang Chen School of Materials Science&Engineering Sichuan UniversityChengdu 610064China Center for Nanoscale Characterization&Devices(CNCD) School of Physics&Wuhan National Laboratory for Optoelectronics(WNLO)Huazhong University of Science and Technology(HUST)Wuhan 430074China Centre for Future Materials University of Southern QueenslandSpringfieldQueensland4300Australia

Rational design has been widely used to develop high-performance metal selenides-based electrode materials for supercapacitors.In this study,we develop a facile one-step solvothermal approach to synthesize binder-free Ni_(3)Se_(2) nanodendrite arrays grown on nickel foam as advanced positive electrodes for supercapacitors.Our Ni_(3)Se_(2) nanodendrite arrays on nickel foam exhibit a specific capacitance of 1234 Fg^(-1)(3.70 F cm^(-2))at a current density of 1 Ag^(-1) and a great rate capability,which is benefited from the excellent electrical conductivity and unique hierarchical nano-dendritic structure.Furthermore,an asymmetric supercapacitor device was assembled using activated carbon as the negative electrode and the Ni_(3)Se_(2) nanodendrite arrays on nickel foam as the positive electrode,obtaining a high energy density of 22.3 W h kg^(-1) at a power density of 160.4 W kg^(-1).

关键词： Ni3Se2 Nanodendrite Binder-free capacitance Supercapacitors

Corrosion behaviors of thermally grown oxide films on Fe-based bulk metallic glasses

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International Journal of Minerals,Metallurgy and Materials 2012年第8期19卷 726-732页

作者： Hong-xiang Li Shan-lin Wang Yeonuk Jeong Seonghoon Yi State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China. School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China. Department of Electronic Materials Science and Engineering Kyungpook National University Daegu 702-701 South Korea. Department of Materials Science and Metallurgy Kyungpook National University Daegu 702-701 South Korea.

Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructural and electrochemical analysis. The oxide film formed at 573 K is iron-rich oxide and it exhibits an n-type semiconductor at a higher potential than 0.35 V and a p-type semiconductor at a lower potential than 0.35 V. capacitance measurements show that the donor density decreases with the increase in oxidation temperature, while the thickness of the space charge layer increases with the oxidation temperature rising. The result of immersion tests shows that the mass loss rate increases with the oxidation temperature rising. Therefore, the correlation between microstructure and corrosion resistance needs to be proposed because the corrosion resistance is deteriorated with the development of the oxide films.

关键词： bulk metallic glass oxide films corrosion capacitance

Interface states in Al_2O_3/AlGaN/GaN metal-oxide-semiconductor structure by frequency dependent conductance technique

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Chinese Physics B 2014年第5期23卷 505-509页

作者：廖雪阳张凯曾畅郑雪峰恩云飞来萍郝跃 Science and Technology on Reliability Physics and Application of Electronic Component Laboratory the 5th Electronics Research Institute of the Ministry of Industry and Information Technology Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

Frequency dependent conductance measurements are implemented to investigate the interface states in Al2O3/A1GaN/GaN metal-oxide-semiconductor （MOS） structures. Two types of device structures, namely, the recessed gate structure （RGS） and the normal gate structure （NGS）, are studied in the experiment. Interface trap parameters includ-ing trap density Dit, trap time constant ιit, and trap state energy ET in both devices have been determined. Furthermore, the obtained results demonstrate that the gate recess process can induce extra traps with shallower energy levels at the Al2O3/AlGaN interface due to the damage on the surface of the AlGaN barrier layer resulting from reactive ion etching （RIE）.

关键词： Al2O3/AlGaN/GaN interface trap states conductance capacitance

Thickening of Non-Ferroelectric Capacitive Layers with Enhanced Domain Switching Speed in Polyvinylidence Fluoride Copolymer Thin Films

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Chinese Physics Letters 2011年第10期28卷 236-239页

作者：刘骁兵孟建伟江安全王建禄 State Key Laboratory of ASIC and System Department of MicroelectronicsFudan UniversityShanghai 200433 National Laboratory Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083

The large coercive field of domain switching in poly(vinylidene fluoride-trifluoroethylene)thin films is in much part due to the contribution of nonpolar impurity phases rather than the manifestation of an intrinsic domain switching mechanism of the ferroelectric layer.We coincidentally derive the equivalent electrical capacitance for the total non-ferroelectric capacitive layers from either domain switching current transient or voltage dependence of the switched polarization.Unexpectedly,the non-ferroelectric capacitance reduces by more than 71%with the enhancement of domain switching speed spanning over 5 orders of magnitude in company with the continuous reduction of the remanent polarization,which suggests the thickening of the above capacitive layers with enhanced domain switching speed.

关键词： ferroelectric capacitance Copolymer