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Comparison of different types of commercial lithium-ion batteries and their properties under low temperature
Bičák, Tomáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of lithium-ion batteries. Describes development, technologies and materials used. The diploma thesis describes the operating principle, characteristics, advantages and disadvantages. The work is focused on the characteristic properties of commercial lithium-ion batteries under standard conditions and at reduced temperatures. At reduced temperatures, changes in properties due to low temperatures are observed. Furthermore, in this work they compare the measured values with the values given by the manufacturers.
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New gel electrolytes based on copolymers for electrochemical power sources
Peterová, Soňa ; Sedlaříková, Marie (referee) ; Veselkova, Iuliia (advisor)
This thesis deals with description of preparation and use of monomers and copolymers for gel polymer electrolytes usable in electrochemical power sources. This thesis is divided in theoretical and experimental part. The theoretical part describes electrolytes focused on gel polymer electrolytes, measuring methods and materials used for experiments. The experimental part deals with calculation of composition of polymer electrolytes, method of preparation and evaluation of measured results. The method of applying GPE to a negative LTO electrode and a positive NMC electrode is described too. Linear Sweep Voltammetry (LSV) and Potentiostatic Electrochemical Impedance Spectroscopy (PEIS), Cyclic Voltammetry (CV) and Galvanostatic Cycling with Potential Limitation (GCPL) were chosen for measurement of properties.
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Low NOx emission combustion chamber of turbine engines
Šafránek, Martin ; Mašek, Jakub (referee) ; Šplíchal, Miroslav (advisor)
Bachelor thesis examines Low NOx emission combustion chamber of turbine engines. It describes in particular the events taking place in the combustion chambers and the mechanisms of generating all monitored emissions. It also focuses on the description of the most important design parameters, their estimated development, assessment and use in civil aviation. Further, this thesis deals with the legislation of various organizations that create certification standards for regulating the amount of emissions emitted.
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Compatibility of negative electrode materials at system of lithium-ion battery
Šikuda, Milan ; Sedlaříková, Marie (referee) ; Libich, Jiří (advisor)
This thesis deals with a study of lithium-ion batteries. It is focused into negative electrode materials and electrolytes. In this thesis is presented synthesis, electrochemical properties, possibilities to improving negative electrode materials as LTO (Lithium Titanate Oxid) and graphite. These electrode materials were investigated with respect to their compatibility at electrolytes with carbonate solvents, Sulfolane and DMF (DiMethylFormamide) in detail. The main aim of this thesis is to characterize electrode materials and electrolyte properties depending on wide range of temperatures and their comparison for the purpose of achievement of the best solution. The thesis is divided into two main parts. The theoretical part of thesis describes composition, process of synthesis and analysis of lithium-ion cell. Practical part contains measuring and evaluating of charge-discharge and irreversible capacity characteristics related to variety of environmental temperatures.
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Methods for Analysis of Switched Circuits
Kovář, Jan ; Ondráček, Oldřich (referee) ; Kalous, Jaroslav (referee) ; Kolka, Zdeněk (advisor)
The dissertation deals with simulations of the DC-DC converters in their basic configurations (Buck, Boost, Buck-boost, Cuk, SEPIC). In the first part of the thesis derivation of transfer functions Line-to-Output (LTO) and Control-To-Output (CTO) can be found. These symbolic responses are derived for three types of basic converters (Buck, Boost, Buck-boost) using well-known average model [1]. Derived expressions are very complicated. For reduction of these expressions symbolic approximation method was used, however the generality is lost. The average model was used to for decreasing the computational effort of analysis of DC-DC converters in the time domain. For these simulations VHDL-AMS language was used. The main topic of the thesis is harmonic balance method, which was adapted to DC-DC converters. Because conditions and assumptions for LTO and CTO functions are very different, harmonic balance method was derived into two variants. For obtaining of LTO response, duty cycle of switching signal can be considered as constant in time. Spectrum of this signal is simple as follows from well-known sinc function. For obtaining of CTO response PWM modulation must be used. Compared to sinc function spectrum of PWM modulation is richer (contains more combination frequencies). Many types of PWM modulation is described in [31]. For simulation PWM modulation with uniform sampling in two variants (single and double edge) was used. Non-ideal switching of PWM switch was modeled by PWM pulse with defined slew rate. Last section deals with comparison of all derived functions (LTO, CTO, modulation type, defined slew rate) with well-known averaged model.
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Expanded Grpahite as Negative Electrode Material for Aporotic Intercalation Systems
Kaňa, Michal ; Čech, Ondřej (referee) ; Libich, Jiří (advisor)
This thesis deals with lithium-ion batteries. It focuses primarily on the materials which are the basis of negative electrode materials, especially on natural expanded graphite. The aim of this thesis is delineate problems of lithium-ion batteries and the possibilities how to improve their basic parameters such a capacity and current carrying capacity. The first part focuses on the description of the functionality of a lithium-ion battery. The second part focuses on the production of negative electrodes, measuring their properties and characteristics. In the last part, there are evaluated and compared individual negative electrode in the role of host of lithium and sodium ions according to the obtained data and then there are the conclusions draw
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SEM Micromanipulator as Current Collector for Battery In-situ Characterization
Klvač, O. ; Kazda, T. ; Fam, Y. ; Novák, L.
The aim of the work is to develop an in-situ method for electrode microstructure investigation by scanning electron microscopy (SEM). In the first part, the preparation of a model battery using FIB-SEM system is described, which consists of lithium metal, ionic liquid, and lithium titanate oxide (LTO) attached on a micromanipulation needle by platinum deposition. The needle is used for handling and at the same time as a current collector, which facilitates subsequent analysis. Open-circuit voltage (OCV), cyclic voltammetry (CV), and galvanostatic cycling measurements (GCPL) was done on the cell assembled (and imaged) in SEM. After seven complete cycles, a cross-section of LTO electrode using FIB was prepared and the surface solid electrolyte interface (SEI) layer was observed. Challenges connected with battery preparation are described and possible solutions for future testing are proposed. The work is evolved in cooperation with Thermo Fisher Scientific Brno.
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Comparison of different types of commercial lithium-ion batteries and their properties under low temperature
Bičák, Tomáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of lithium-ion batteries. Describes development, technologies and materials used. The diploma thesis describes the operating principle, characteristics, advantages and disadvantages. The work is focused on the characteristic properties of commercial lithium-ion batteries under standard conditions and at reduced temperatures. At reduced temperatures, changes in properties due to low temperatures are observed. Furthermore, in this work they compare the measured values with the values given by the manufacturers.
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In-Situ Sem Characterization Of Lithium-Ion Battery Created On Mems Chip
Klvač, Ondřej
The aim of the work is to develop an in-situ method for electrode nanostructure investigationby scanning electron microscopy. In the first part, the preparation of a model battery using FIBSEMsystem is described, which consists of lithium titanate oxide (LTO) and metallic lithium materialcutting by the focused ion beam, transport to the MEMS chip, and contacting by carbon deposition.After that the electrodes were soaked by the electrolyte, the voltage changes were measured ontwo created battery systems. Finally, a current was applied to the cell. However, cycling failed dueto technological problems. Challenges connected with battery preparation are described and possiblesolutions for future testing are proposed. The work is evolved in cooperation with Thermo FisherScientific Brno.
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