• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 58
  • 8
  • 4
  • 1
  • Tagged with
  • 85
  • 85
  • 13
  • 7
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Analysis of Optimization Processses for Solid State Fabrication of Olivine Cathode Materials

Unknown Date (has links)
Lithium ion battery discovered since the 1980s has become pivotal to our energy needs. With the need for a shift to renewable energy and increased use of portable devices, energy storage has become a very important aspect of modern day life and technology. In the thesis, optimization techniques for solid state calcination of lithium olivine batteries are characterized and analyzed. A brief introduction into lithium ion battery is discussed, the chemistry and physics of the materials is studied in details. Emphasis is placed on the olivine structure, industrially utilized synthesis method and the performance of olivine lithium ion batteries are also discussed in details. Olivine structure LiFePO₄ (LFP) was synthesized via solid state processes, using Li₂CO₃, NH₄H₂PO₄ and FeC₂O₄·H₂O and C₁₂H₂₂O₁₁ as precursor materials. The effects of calendaring in terms of charge/discharge capacity, cycle life performance, surface morphology, and ac impedance was analyzed. The resulting LFP electrode was divided in part, Part A was left as is and Part B was calendared. The calendared electrode exhibited lower impedance under electrochemical impedance test. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at 0.1C compared to the as-is electrode with discharge capacity of about 120mAh/g. Olivine structure LiMnPO₄ (LMP) was also synthesized via solid state processes, using Li₂CO₃, NH₄H₂PO₄, MnCO₃ and C₁₂H₂₂O₁₁ as precursor materials. Comparison of the carbon addition process was done by adding sucrose to the initial precursor mix and carbon black at the later stages of fabrication. The 3 step carbon addition exhibited the highest specific capacity of about 72mAh/g, 1 step carbon addition possessed the least capacity of about 45mAh/g, while the 2 step process had a capacity of about 65mA/g. / A Thesis submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the Master of Science. / Summer Semester 2015. / June 29, 2015. / Includes bibliographical references. / Pedro L. Moss, Professor Directing Thesis; Mark H. Weatherspoon, Committee Member; Petru Andrei, Committee Member.
2

Development of New Generation Hybrid Lithium-Ion Battery Capacitor Energy Storage Devices

Unknown Date (has links)
As the energy demand grows so to do the need for devices that can be tailored to a design need. Often, this can lead to a device that falls between the two traditional groups of lithium-ion battery (LIB) and lithium-ion capacitors (LIC). An emerging way to bring these devices together is using composite cathodes. Composite cathodes combine a battery material with capacitor material and have shown to be able to enhance life cycle energy and power performance compared to their non-composite counterparts. The initial focus of the investigation is into the performance impact of LiNi0.5Co0.2Mn0.3O2 (NMC) as an additive to Activated Carbon (AC) electrodes within a high-performance Li-ion capacitor fabricated with activated carbon positive electrodes (PEs) and hard carbon negative electrodes (NEs) having lithium thin film as Li sources loaded on the surface of the negative electrodes. We report here on a hybrid LIC consisting of a Lithium nickel cobalt manganese oxide /activated carbon composite cathode in combination with an ultra-thin lithium film (u-Li) pre-loaded hard carbon anode. Additionally, we show that by utilizing three design approaches: dry composite electrode fabrication method, cathode to anode capacity ratio design, and pre-lithiation method using u-Li, we can demonstrate an energy storage device with excellent cycle life, and that can be tailored by composite ratios within the cathode to fit different applications. Shown here is an in-depth look at various composite material ratios, pre-lithiation calculations, and hybrid lithium-ion battery-capacitor energy storage device creation based on targeting essential energy-power performance characteristics. / A Dissertation submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2019. / April 17, 2019. / cycle life, dry method composite hybrid cathode, Hybrid Li-ion battery-capacitor, lithium nickel cobalt manganese oxide, pre-lithiation, Ragone plots / Includes bibliographical references. / Jim P. Zheng, Professor Directing Dissertation; Chiang Shih, University Representative; Petru Andrei, Committee Member; Simon Y. Foo, Committee Member; Hui Li, Committee Member.
3

Mechanische Arbeit der Kräfte und Leistungen der Maschinen

Hallbauer, Anton. January 1842 (has links)
Programm--k. Gewerbschule und Baugewerkenschule zu Zittau.
4

Mechanische Arbeit der Kräfte und Leistungen der Maschinen

Hallbauer, Anton. January 1842 (has links)
Programm--k. Gewerbschule und Baugewerkenschule zu Zittau.
5

Das Princip der Erhaltung der Energie als Grundlage der elementaren Dynamik

Januschke, Hans, January 1884 (has links)
Program--Staats-ober-realschule in Troppau.
6

Certain aspects of energy transformations in the Northern Hemisphere

Carasso, Alfred S. January 1964 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. [32]-33.
7

Das Princip der Erhaltung der Energie als Grundlage der elementaren Dynamik

Januschke, Hans, January 1884 (has links)
Program--Staats-ober-realschule in Troppau.
8

Die philosophiegeschichtlichen voraussetzungen der energetik ...

Tscheuschner, K. January 1901 (has links)
Inaug.-diss.--Bern. / "Quellenangabe": 1 p. following p. 48.
9

A framework for energy in South Africa with special reference to a long term forecast for energy demand

09 February 2015 (has links)
M.Phil. / The construction of mathematical models for making projections of future energy demand is an important step in the formulation of an energy policy for a country or region. In this dissertation the different approaches to energy modelling are investigated. The history of the modelling effort in the world and South Africa is briefly discussed. The development of a comprehensive database is of vital importance for the success of any modelling effort. An energy database for South Africa was developed. An existing energy forecasting model was updated and extended to cover eleven final consuming sectors. Projections of energy demand were made to illustrate the mechanism of the model.
10

Analysis of High Switching Frequency Quasi-Z-Source Photovoltaic Inverter Using Wide Bandgap Devices

Unknown Date (has links)
N/A / A Dissertation submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2017. / June 12, 2017. / Includes bibliographical references. / Hui Li, Professor Directing Dissertation; Juan Ordonez, University Representative; Chris Edrington, Committee Member; Sastry Pamidi, Committee Member; Thomas A. Lipo, Committee Member.

Page generated in 0.0572 seconds