Power and Energy Commons^™

Cmk-3/Sulfur Composite (CXSY) And Room-Temperature Na/S Battery, Qing Zhao, Yu-Xiang Hu, Kai Zhang, Li-Jiang Wang, Zhan-Liang Tao, Jun Chen

Journal of Electrochemistry

A series of ordered mesoporous carbon (CMK-3)/sulfur composite (C_xS_y) with different sulfur contents were synthesized via a melt-diffusion method. XRD, Raman, BET, SEM, and TEM techniques were used to characterize the structure and morphology of the as-prepared composite. The electrochemical performance of CMK-3/sulfur composite as the electrode of Na/S battery was tested at room temperature. Cyclic voltammograms show that one obvious reduction peak was located at about 1.61V, which is corresponding to the formation of Na₂S_x (x=2~5), while two oxidation peaks were displayed at about 1.82V and 1.95V, which are belonging to the …

Surface Composition Structure And Electrochemical Performance Of Aluminum Doped Lifepo4, Huai-Fang Shang, Wei-Feng Huang, Wang-Sheng Hu, Ding-Guo Xia, Zi-Yu Wu

Journal of Electrochemistry

Despite there are many successful reports about the preparation of electrode materials with surface coating for lithium ion batteries, the study in surface self-coating of cathode materials using segregation of doping elements and their electrochemical properties is still very rare. The LiFePO₄ particles with rich-Al on the surface were synthesized by one step solvothermal route. TEM results demonstrated that the surface of the obtained LiFePO₄ particles was well-covered by the amorphous coating. The soft X-ray absorption spectroscopy (XAS) and Auger electron spectroscopy (AES) component analyses revealed that the amorphous coating was composed of LiFe_1-xAl_xPO …

Controllable Synthesis Of Dispersed Spherical Fe3O4 Nanoparticles As Lithium-Inserted Materials, Hong-Li Zou, Wei-Shan Li

Journal of Electrochemistry

Dispersed spherical Fe₃O₄ nanoparticles were synthesized by a hydrothermal method. The influences of odecyl trimethyl ammonium bromide (DTAB) concentration on the morphology and particle size of the as-prepared Fe₃O₄ were studied. Electrochemical performance of the as-prepared sample as anode materials of lithium ion battery was investigated. It is found that the as-prepared sample exhibits superior rate performance and cycle performance. The nano-sized materials provide structural stability and favor the transfer of lithium ions.

Electrochemical Na-Storage Materials And Their Applications For Na-Ion Batteries, Jiang-Feng Qian, Xue-Ping Gao, Han-Xi Yang

Journal of Electrochemistry

Oncoming large scale electric energy storage (EES) requires battery systems not only to have sufficient storage capacity but also to be cost-effective and environmentally friendly. Li-ion batteries for widespread EES applications may be limited due to the constraint of global lithium resource. From the considerations of available resources and environmental impact, Na-ion batteries have potential advantages as next generation secondary batteries and an alternative to Li-ion batteries. However, in the present state of the art, the Na-storage cathodes reported so far are still deficient both in energy density and power capability, while the carbon and alloy anodes for Na-ion batteries …

Application Of Synchrotron Radiation Based Electrochemical In-Situ Techniques To Study Of Electrode Materials For Lithium-Ion Batteries, Zheng-Liang Gong, Wei Zhang, Dong-Ping Lv, Xiao-Gang Hao, Wen Wen, Zheng Jiang, Yong Yang

Journal of Electrochemistry

Due to its merits of high brightness and high intensity, high level of polarization and wide tunability in energy, etc., synchrotron radiation technique provides an unique platform for analysis of the relationship among composition–structure–performance of materials for lithium ion batteries, especially for in-situ, real time dynamic investigation of the electrochemical reaction mechanism, aging process and failure mechanism during charge-discharge cycling. In this paper, we review the latest developments in application of synchrotron based electrochemical in-situ experimental methods to studies of lithium ion batteries. The paper mainly focuses on the application of electrochemical in-siu XRD and XAFS techniques to the investigations …

Preparation And Electrochemical Properties Of Amorphous Znsno3/C By Hydrothermally Carbonization Method, Guo-Qing Fang, Rui-Xue Zhang, Wei-Wei Liu, Bing-Bo Xia, Hong-Dan Sun, Hai-Bo Wang, Jing-Jing Wu, Shinko Kaneko, De-Cheng Li

Journal of Electrochemistry

The amorphous ZnSnO₃@C composite was synthesized via a simple glucose hydrothermal and subsequent carbonization approach. The structure, morphology and electrochemical property of the composite were characterized by XRD, TEM and electrochemical measurements. Compared to bare ZnSnO₃, the ZnSnO₃/C composite exhibited markedly enhanced lithium storage property and cycle performance, delivering a reversible capacity of 659 mAh·g^-1 after 100 cycles at a current density of 100 mA·g^-1.

An Investigation On The Solid Electrolyte Interphase Of Silicon Anode For Li-Ion Batteries Through Force Curve Method, Jie-Yun Zheng, Hao Zheng, Rui Wang, Hong Li, Li-Quan Chen

Journal of Electrochemistry

Non-aqueous electrolyte has been widely used in commercial Li-ion batteries. Optimized choices are proceeding among the various types of salts and solvents in an effort to achieve higher performance of electrolyte. However, the electrolyte will be reduced in low potential and the reductive product will be deposited on the surface of anode to form a passivating layer, solid electrolyte interphase (SEI). Herein an atomic force microscopy (AFM) based method was introduced to study the structure and mechanical property of SEI on silicon thin film anode during the first cycle. Silicon has been known as the most potential candidate anode for …

Aqueous Solution-Evaporation Route Synthesis And Phase Structural Research Of The Li-Rich Cathode Li1.23Ni0.09Co0.12Mn0.56O2 By In-Situ Xrd, Chong-Heng Shen, Shou-Yu Shen, Zhou Lin, Xiao-Mei Zheng, Hang Su, Ling Huang, Jun-Tao Li, Shi-Gang Sun

Journal of Electrochemistry

The Li-rich Li_1.23Ni_0.09Co_0.12Mn_0.56O₂ material was synthesized via aqueous solution-evaporation route. The structure and morphology of the material were characterized by means of XRD and SEM. The results indicated that the single particle of the product was polygonal with the size of 330 nm and the structure was layered solid solution with a certain amount of Li₂MnO₃. Electrochemical tests showed that the first discharge capacity of the Li-rich layered material was 250.8 mAh·g^-1 at 0.1C，the capacity retention was 86.5% after 40 cycles. Through in-situ XRD study a …

Synthesis And Electrochemical Property Of Li2Fesio4/C Cathode Material By Solid State Method, Jiao-Li Sun, Zhi-Jiao Chen, Yi-Xiao Li, Hu Cheng

Journal of Electrochemistry

Li2FeSiO4/C cathode material was synthesized using Li₂SiO₃ and FeC₂O₄ as raw materials by solid state method. The structure and morphology of the material were characterized by XRD and SEM. The electrochemical properties of the material were studied by constant-current cyclic testing. The results show that Li₂FeSiO₄/C has a good electrochemical performance. The first discharge capacity of Li₂FeSiO₄/C cathode material at 30oC reached 167 mAhg^-1 when cycled at 10 mAg^-1 between 1.5 and 4.8 V.

Preparation And Electrochemical Properties Of Flake-Like Liv3O8 By Soft Template Assisted Sol-Gel Method As Anode Material For Aqueous Li-Ion Battery, Shuai Tan, Dan Sun, Hai-Yan Wang, Tian-Li Hou, Zhong-Xing Xiao, You-Gen Tang

Journal of Electrochemistry

Anode material has become the key issue for restricting the development of aqueous lithium ion battery (ALIB). Flake-like LiV3O8 materials were synthesized by sol-gel method using sodium dodecyl benzene sulfonate (SDBS) as a template. The XRD and SEM results showed that as-prepared flake-like LiV₃O₈ was of high purity with monoclinic system and P21/m space group. LiMn₂O₄//Li₂SO₄//LiV₃O₈ ALIB was assembled and tested. As observed, the flake-like LiV3O8 here exhibited good high-rate performance and cycling stability. A high discharge capacity of 154 mAh.g^-1 (based on the mass …

Synthesis And Electrochemical Performance Of Nano Licopo4 By Polyol Method, Fei Wang, Yang Jun

Journal of Electrochemistry

High potential LiCoPO₄ cathode material was synthesized by polyol method. Carbon layer of ca. 3 nm thick was coated on the LiCoPO4 surfaces by chemical vapor deposition from methylbenzene. Crystalline structure, morphology and electrochemical performance of the sample were studied by XRD, SEM, TEM, CV and galvanostatic charge/discharge curve. The synthesized material via polyol method showed a pure phase of LiCoPO₄. The LiCoPO₄/C electrode delivered a high discharge capacity of 132 mAh·g^-1 and maintained 78% of the initial capacity after 50 cycles at 0.1C rate. The two-step extraction/insertion behavior of Li⁺ in LiCoPO4/C …

Preparation Of The Particle Size Controllable Lifepo4/C And Its Electrochemical Profile Characterization, Ming-E Wang, Jing-Yuan Liu, Meng-Yan Hou, Yong-Yao Xia

Journal of Electrochemistry

We adopted an effective route to prepare the particle size controllable core-shell structure carbon-coated LiFePO4 from different sized FePO4 precursors, varying from 80 nm, 200 nm and 1 μm by an in situ polymerization method integrated with a surface modification technology. The discharge capacities of the three sized LiFePO₄/C are, respectively, 162 mAh·g^-1, 142 mAh·g^-1 and 92 mAh·g^-1 at 0.1C rate. The nano-sized LiFePO₄-a/C (80 nm) delivers a discharge capacity as large as 100 mAh·g^-1 even at 30C, while the macroscopic LiFePO₄-c/C (1 μm) exhibits a much poorer discharge …

Predicting Voltage Abnormality Using Power System Dynamics, Nagendrakumar Beeravolu

University of New Orleans Theses and Dissertations

The purpose of this dissertation is to analyze dynamic behavior of a stressed power system and to correlate the dynamic responses to a near future system voltage abnormality. It is postulated that the dynamic response of a stressed power system in a short period of time-in seconds-contains sufficient information that will allow prediction of voltage abnormality in future time-in minutes. The PSSE dynamics simulator is used to study the dynamics of the IEEE 39 Bus equivalent test system. To correlate dynamic behavior to system voltage abnormality, this research utilizes two different pattern recognition methods one being algorithmic method known as …

Battery Energy Storage Systems To Mitigate The Variability Of Photovoltaic Power Generation, Heath Alan Gurganus

Dissertations and Theses

Methods of generating renewable energy such as through solar photovoltaic (PV) cells and wind turbines offer great promise in terms of a reduced carbon footprint and overall impact on the environment. However, these methods also share the attribute of being highly stochastic, meaning they are variable in such a way that is difficult to forecast with sufficient accuracy. While solar power currently constitutes a small amount of generating potential in most regions, the cost of photovoltaics continues to decline and a trend has emerged to build larger PV plants than was once feasible. This has brought the matter of increased …

New Three-Phase Multilevel Inverter With Reduced Number Of Power Electronic Components, Saad Mekhilef

Saad Mekhilef

In this paper, a new configuration of a three-phase five-level multilevel voltage-source inverter is introduced. The proposed topology constitutes the conventional three-phase two-level bridge with three bidirectional switches. A multilevel dc link using fixed dc voltage supply and cascaded half-bridge is connected in such a way that the proposed inverter outputs the required output voltage levels. The fundamental frequency staircase modulation technique is easily used to generate the appropriate switching gate signals. For the purpose of increasing the number of voltage levels with fewer number of power electronic components, the structure of the proposed inverter is extended and different methods …

Development Of Si Device Based Power Converters For High Temperature Operation In Hev Applications, Zhuxian Xu

Doctoral Dissertations

In this dissertation, the feasibility of operating Si devices at 200 ˚C [degree Celsius] is investigated and the guidelines on the development of a high temperature Si converter for operating with 105 ˚C high temperature liquid coolant in hybrid electrical vehicle (HEV) applications are provided.

First, the characterization of a Si IGBT operating at 200 ˚C junction temperatures is presented. It is shown that the commercial 175 ˚C Si IGBT under test can be successfully switched at an elevated junction temperature of 200 ˚C with increased but acceptable losses.

Second, a comprehensive evaluation of Si IGBT ruggedness at high temperature …

Wide-Area Measurement And Applications In Power System Dynamic Modeling And Control, Yong Liu

Doctoral Dissertations

Synchrophasor has been becoming the foundational element of power grid wide-area measurement system (WAMS) since first developed in 1980s. By utilizing global positioning system (GPS) time synchronization technique, synchrophasors offer highly accurate time-synchronized phasor measurements that can provide system operators with real-time information of operation status.

Frequency disturbance recorders (FDRs) are installed on the distribution level to measure power system dynamics and considered as a type of single-phase synchrophasors. In this dissertation, a detailed procedure for the FDRs’ calibration is summarized and a preliminary test of their dynamic performance is carried out. Moreover, this dissertation investigates the impact of GPS …

All-Sic Three-Phase Converters For High Efficiency Applications, Fan Xu

Doctoral Dissertations

The dissertation aims to improve the efficiency of three-phase converters using SiC power devices.The methodology to design a high efficiency all-SiC three-phase converter is presented. Four aspects are included: SiC power device evaluation, power loop parasitics analysis, high efficiency current source rectifier, and paralleled current source rectifier system.

The SiC JFET and MOSFET are tested based on voltage source and current source structures respectively. The dissertation proposes a device switching test circuit based on current source topology to simulate current commutation processes. The circuit can evaluate the switching performance and calculate switching loss of a power device used in a …

Portable Nano-Hydro Power Generator For The Dc House Project, Andrew Aw, James Biggs

Electrical Engineering

This senior project report explains the construction and design of a small, portable water generator that converts kinetic energy flowing in small creeks to electrical energy as a renewable source of energy for the DC House. The DC House, in short, is a project to build a self-sustainable house for Third World countries that utilizes only DC electricity. The system consists of two converters and a charge controller for a 12V lead-acid battery. The first converter converts the hydro generator voltage output to 15 Volts for safe and proper charging of the lead-acid battery by the charge controller. The second …

Motor Protection Lab Experiment Using Sel-710, Ozro Corulli

Electrical Engineering

Advancements in microprocessor based relay technology for power protection applications provide quicker response times and new methods of mitigation. This project develops a lab experiment for Cal Poly class EE444 - Power Systems Laboratory based on the Schweitzer SEL-710 motor protection relay. Learning objectives for this lab include relay setup, programming, and protection schemes for the following conditions: undervoltage, loss of phase, fault, locked rotor, and thermal overload. Today, utility companies across the globe use SEL relays for primary system protection, putting engineers familiar with their operation in high demand.

Arm Inductance And Sub-Module Capacitance Selection In Modular Multilevel Converter, Yalong Li

Masters Theses

Arm inductor and sub-module (SM) capacitor are two key components in the modular multilevel converter (MMC). Optimizing the selection of arm inductance and sub-module capacitance is thus critical for the converter design. This report aims at developing a selection principle for arm inductance and sub-module capacitance in MMC.

Arm inductors in MMC are used to limit the circulating current which flows within the converter. The switching frequency harmonic is found to be the dominant component in the circulating current when an active circulating current suppressing controller is implemented. The analytical relationship between the arm inductance and switching frequency circulating current …

An Occupant-Based Dynamic Simulation Tool For Predicting Residential Power Demand And Quantifying The Impact Of Residential Demand Response, Brandon Jeffrey Johnson

Masters Theses

With their large impact on the power system and widespread distribution, residential loads provide vast resources that if utilized correctly have the potential to help reduce both electricity cost and demand throughout the day. Previous research in this area has been primarily focused on building more energy efficient homes and improving the efficiencies of appliances and lighting technologies. Far less attention has been given to the ability of residential loads to provide various demand response services. Residential loads with demand response capabilities have the potential to be very useful in both peak shifting and regulation applications, and could be utilized …

Fea Estimation And Experimental Validation Of Solid Rotor And Magnet Eddy Current Loss In Single-Sided Axial Flux Permanent Magnet Machines, Xu Yang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The rotor and magnet loss in single-sided axial ux permanent magnet (AFPM) machines with non-overlapped windings is studied in this dissertation. Finite element analysis (FEA) estimations of the loss are carried out using both 2D and 3D modeling. The rotor and magnet losses are determined separately for stator slot passing and MMF space harmonics from currents in the stator. The segregation of loss between the solid rotor plate and the magnet is addressed. The eddy current loss reduction by magnet segmentation is discussed as well. Two prototype 24 slot/22 pole single-sided AFPMs, fabricated with both single layer (SL) and double …

Design, Fabrication And Characterization Of Plasmonic Fishnet Structures For The Enhancement Of Absorption In Thin Film Solar Cells, Sayan Seal

Graduate Theses and Dissertations

Incorporating plasmonic structures into the back spacer layer of thin film solar cells (TFSCs) is an efficient way to improve their performance. The fishnet structure; which is a tunable, plasmonic light scatterer is used to enhance light absorption. Unlike other plasmonic particles that have been previously suggested, the fishnet is an electrically connected wire mesh and does not result in electric field localization, hence it results in greater absorption in the intrinsic Si layer. Unlike other designs, the fishnet structure is placed in the back spacer layer of the TFSC, so it does not block any incident light. There is …

Modeling And Protection Of Phase Shifting Transformers, Umar Khan

Electronic Thesis and Dissertation Repository

This thesis is mainly focused on the development of (i) phase shifting transformers (PSTs) mathematical and simulation models that can be used for the short-circuit and protection studies, and (ii) new phase shifting transformers protection methods that provide more secure and sensitive solutions than the standard current differential protection.

The first part of this thesis describes and presents the modeling of the single-core standard-delta, and two-core symmetrical and asymmetrical PST for protection and short-circuit studies. The models already available for such types of PSTs have limitations and require detailed test report data from the manufacturers. However, winding test data at …

Impact Of Renewable Power Integration On Vq Stability Margin, H. W. K. M. Amarasekara, Lasantha Meegahapola, Sarath Perera, Ashish Agalgaonkar

Dr Lasantha G Meegahapola

With the increasing number of grid connected renewable energy sources in power systems, the requirements for in-depth studies to characterise the dynamics of power systems have also intensified. In this paper, the impact of renewable power generators on power system voltage stability is analysed. As the renewable power penetration increases, having adequate levels of reactive power generation in power systems for voltage support is a major challenge. Therefore, in this work, special attention was placed on VQ instability to investigate static voltage stability of a test network embedded with renewable power generation. The impact of different control strategies associated with …

Preparation Of Benzoquinone From Phenol By Electrooxidation, Dong-Fang Niu, Cheng-Kai Yu, Xin-Sheng Zhang

Journal of Electrochemistry

The benzoquinone was prepared from phenol by electrooxidation in an H-type cell with cation exchange membrane, in which lead plates were used both as an anode and a cathode, while H₂SO₄ was used as a supporting electrolyte. The effects of current density, concentration of sulphuric acid, concentrations of benzoquinone in electrolyte and extractant on the yields and efficiencies of electrolysis were investigated. Under the optimized conditions of current density being 4 A·dm^-2, concentration of sulphuric acid 1 mol·L^-1, passed charge 3.2 A·h, the yield and current efficiency of benzoquinone could reach 68% and …

Experimental Design Methodology Applied To The Oxidation Of Quinolines In Aqueous Medium By Electro-Fenton Process, Souissi Souhaila Trabelsi, Nihal Oturan, Nizar Bellakhal, Mehmet A. Oturan

Journal of Electrochemistry

The degradation behavior of 8-hydroxyquinoleine sulfate (8-HQS), a model molecule of quinolines, was studied in an aqueous medium by electro-Fenton process using a carbon felt cathode and a platinum anode. The great oxidation ability of this process is due to a large production of hydroxyl radical (OH) by electrochemically induced Fenton’s reagent (H2O2, Fe2+). Hydroxyl radicals are very powerful oxidizing agents which react on organics up to complete mineralization. A factorial experimental design was used for determining the operating parameters on the degradation of 8-HQS in an aqueous medium. The results showed that the current intensity and the initial concentration …

Synthesis Of Pani/Nihcf Nanocomposite Particles And Eqcm Measurement Of Ion Exchange Properties In Solutions Containing Cd2+, Yu-Jiao Yang, Xiao-Gang Hao, Xu-Li Ma, Zhong-De Wang, Zhong-Lin Zhang, Nian-Chen Han

Journal of Electrochemistry

The PANI/NiHCF nanocomposite particles were synthesized on the CNTs-modified Pt substrate by one-step co-polymerization using cyclic voltammetry. Electrochemical quartz crystal microbalance (EQCM) technique was adopted to investigate the polymerization process of the nanocomposite particles and the mechanism of ion exchange in aqueous solution containing Cd²⁺． The morphology and structure of the as-prepared composite particles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). Combined with cyclic voltammetry (CV) and energy dispersive spectroscopy (EDS), the electrochemical behavior and the mechanism of ion exchange were also investigated in electrolytes of Cd^{2+ …}

A Comparative Study In Pretreatments Of Acid Chemical Wastewater By Electrochemical Oxidation And Ozonation, Han-Shui Liu, Su Yu, Shao-Ping Tong, Chun-An Ma

Journal of Electrochemistry

Under the condition of keeping certain acidity, the pretreatment efficiency of an acid chemical wastewater (pH 0.85) by electrochemical oxidation was compared with that by ozonation. The results showed that the electrochemical oxidation pretreatment could obtain a better result than the ozonation at pH 0.85. After the addition of 2 g·L^-1 NaCl and with the electrochemical oxidation pretreatment at 30 mA·cm^-2, the removal rate of chemical oxygen demand (CODCr) reached 43.4%, and the value of biochemical oxygen demand/chemical oxygen demand (BOD₅/COD_Cr) also increased from 0.034 to 0.14 in 20 minutes, indicating significantly improvement …