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Synthesis and Electrochemical Characterization of Iron Oxide / Activated Carbon Composite Electrode for Symmetrical Supercapacitor

Year: 2013 Volume: 7 Issue: 8 591 - 595 Pages

• Authors:
• PoiSim Khiew
• MuiYen Ho
• ThianKhoonTan
• WeeSiong Chiu
• Roslinda Shamsudin
• Muhammad Azmi Abd-Hamid
• ChinHua Chia

Abstract: In the present work, we have developed a symmetric electrochemical capacitor based on the nanostructured iron oxide (Fe3O4)-activated carbon (AC) nanocomposite materials. The physical properties of the nanocomposites were characterized by Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical performances of the composite electrode in 1.0 M Na2SO3 and 1.0 M Na2SO4 aqueous solutions were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The composite electrode with 4 wt% of iron oxide nanomaterials exhibits the highest capacitance of 86 F/g. The experimental results clearly indicate that the incorporation of iron oxide nanomaterials at low concentration to the composite can improve the capacitive performance, mainly attributed to the contribution of the pseudocapacitance charge storage mechanism and the enhancement on the effective surface area of the electrode. Nevertheless, there is an optimum threshold on the amount of iron oxide that needs to be incorporated into the composite system. When this optimum threshold is exceeded, the capacitive performance of the electrode starts to deteriorate, as a result of the undesired particle aggregation, which is clearly indicated in the SEM analysis. The electrochemical performance of the composite electrode is found to be superior when Na2SO3 is used as the electrolyte, if compared to the Na2SO4 solution. It is believed that Fe3O4 nanoparticles can provide favourable surface adsorption sites for sulphite (SO3 2-) anions which act as catalysts for subsequent redox and intercalation reactions.

• Keywords:
• Metal oxide nanomaterials
• Electrochemical Capacitor
• Double Layer Capacitance
• Pseduocapacitance

Design of SiC Capacitive Pressure Sensor with LC-Based Oscillator Readout Circuit

Year: 2012 Volume: 6 Issue: 4 379 - 382 Pages

• Authors:
• Azza M. Anis
• M. M. Abutaleb
• Hani F. Ragai
• M. I. Eladawy

Abstract: This paper presents the characterization and design of a capacitive pressure sensor with LC-based 0.35 µm CMOS readout circuit. SPICE is employed to evaluate the characteristics of the readout circuit and COMSOL multiphysics structural analysis is used to simulate the behavior of the pressure sensor. The readout circuit converts the capacitance variation of the pressure sensor into the frequency output. Simulation results show that the proposed pressure sensor has output frequency from 2.50 to 2.28 GHz in a pressure range from 0.1 to 2 MPa almost linearly. The sensitivity of the frequency shift with respect to the applied pressure load is 0.11 GHz/MPa.

• Keywords:
• CMOS LC-based oscillator
• micro pressure sensor
• silicon carbide

Automatic Generation Control of an Interconnected Power System with Capacitive Energy Storage

Year: 2010 Volume: 4 Issue: 3 392 - 397 Pages

• Authors:
• Rajesh Joseph Abraham
• D. Das
• Amit Patra

Abstract: This paper is concerned with the application of small rating Capacitive Energy Storage units for the improvement of Automatic Generation Control of a multiunit multiarea power system. Generation Rate Constraints are also considered in the investigations. Integral Squared Error technique is used to obtain the optimal integral gain settings by minimizing a quadratic performance index. Simulation studies reveal that with CES units, the deviations in area frequencies and inter-area tie-power are considerably improved in terms of peak deviations and settling time as compared to that obtained without CES units.

• Keywords:
• Automatic Generation Control
• Capacitive EnergyStorage
• Integral Squared Error.