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XRD characterization of electrodes and electrode materials for electrochemical power sources
Klvač, Ondřej ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The thesis describes available choices of methods for research of electrochemical power source electrode strcture by x-ray diffraction spectroscopy. At first there is a theoretical computation of difractogram. Then there are discussed possibilities of in-situ and ex-situ techniques as background research. Practical part of thesis compares theoretical assumptions to measurements of lithium and sodium cells, including analyze of crystallographic phases and lattice constants. As a conclusion, there are discussed possibilities of subsequent research.
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Design and testing of XRD holder for post-mortem analysis of li-ion battery electrodes performed in an inert atmosphere
Klvač, Ondřej ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The work describes the design and manufacturing of a test device for post-mortem measurements of electrodes of electrochemical cells using X-ray diffraction spectroscopy. The theoretical part describes the diffractometer Rigaku Miniflex 600, for which the product is intended. At the same time, an overview of solutions in various applications is processed here in the form of a recherche. The practical part documents the current development of a new cell, on which tests were performed. Here is an overview of the influence of gases and insulating materials on the resulting data, especially distortion and attenuation. Subsequently, a new design with improved hermetic insulation and sample displacement error correction is described. The principle of operation of the manufactured cell, including the control unit and software, is elaborated in the form of technical documentation. Finally, the functionality is verified by comparing the diffractograms of the powder standards and the graphite electrodes.
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Measurement and recording of the initial magnetization curve and hysteresis curve of ferromagnetic materials
Tran, Quoc Bao ; Vaněk, Jiří (referee) ; Klvač, Ondřej (advisor)
This thesis deals with the measurement of primary magnetization curves and hysteresis loop. The thesis is divided into two parts, the theoretical part and the practical part. The theoretical part describes the creation of magnetic field in materials, excitation of magnetic field by electric current or excitation of electric current by changing magnetic field. The practical part is focused on designing, construction and testing of amplifier and the measurement and displaying of hysteresis loop. In the end of the thesis is summarized what results were achieved.
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Review of In-situ and Ex-situ Techniques for Characterization of Li-ion Batteries
Klvač, Ondřej ; Kazda, Tomáš
This paper describes the analytical techniques andsample preparation methods used in in-situ and ex-situ investigationsof Li-ion batteries (LIBs). The introduction briefly describesthe current state of Li-ion batteries and their aging mechanisms.The article is further divided into a description of ex-situ and insitutechniques. Ex-situ techniques include a detailed descriptionof sample preparation for repeatable results using Broad IonBeam (BIB) polisher. In-situ techniques are described in theform of a report of selected published experiments. The paper isfurther extended with our experiments involving ex-situ analysesof cylindrical and flat cell types using BIB in planar modeand cross-section mode. In the case of in-situ experiments, thedesign of the cell inside the SEM chamber is described. Twoexperiments have been performed - on the surface of a MEMSchip, and also using a micromanipulator as a current collectorof the investigated electrode.
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Analýza deformace dřeva s imperfekcí na základě srovnání jednoduchého numerického modelu s optickou metodou DIC
Klvač, Ondřej
This work is devoted to the analysis of wood with imperfection in tension, digital image correlation method and finite element method. It is investigated the comparability of the results of these two methods on the example of behaving of the wood in tension with imperfection. The imperfection could be for example any weakening of the wood structure. It could be natural (knots, cracks and so on). The example of artificial imperfection here is a drilled hole. In this work an experiment with plastic sample in the same manner was also conducted in order to validate the analytical procedure for calculating the stress and practically demonstrate the difference between isotropic and anisotropic material. The work also includes general information from the literature, theoretical assumptions, methodologies, measured results and the comparison of these results each other and with the literature. The result of this work is to evaluate the behavior of wood with a hole in the tension and the comparison of these two methods of measuring deformation. In the end there are the advantages and disadvantages of each method.
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Measurement and recording of the initial magnetization curve and hysteresis curve of ferromagnetic materials
Tran, Quoc Bao ; Vaněk, Jiří (referee) ; Klvač, Ondřej (advisor)
This thesis deals with the measurement of primary magnetization curves and hysteresis loop. The thesis is divided into two parts, the theoretical part and the practical part. The theoretical part describes the creation of magnetic field in materials, excitation of magnetic field by electric current or excitation of electric current by changing magnetic field. The practical part is focused on designing, construction and testing of amplifier and the measurement and displaying of hysteresis loop. In the end of the thesis is summarized what results were achieved.
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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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The Design Of Sample Holder For Xrd Measurements In Inert Atmosphere With Displacement Error Correction
Klvač, Ondřej
This article describes a designed of a holder for post-mortem XRD measurements of Li-ion, Na-ion and Li-S electrodes, which need to be performed in the inert atmosphere. The first part describes the measurement method and problems arising during the measurements of the samples. Subsequently, the design and construction of a new cell with hermetic insulation and sample displacement error correction possible during the operation of the diffractometer is described. Finally, the inert gas attenuation within the cell is theoretically calculated. The calculation is verified by practical measurements, and alternatives are proposed to improve the signal-to-noise ratio.
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Ex-Situ Xrd Characterization Of Electrodes For Electrochemical Power Sources
Klvač, Ondřej
The article describes a theoretical method of a research of graphite electrodes in an electrochemical cell where the problem is with the preferred orientation and a thin layer. As a result, only a reflection (002) is visible. However, there is a possibility to determine crystallographic parame-ters from these peaks because of the effect of a destructive and constructive interference caused by intercalated lithium atoms. At the same time, the work shows that Kapton is not a suitable material for ex-situ cell production, as samples have been destroyed by air humidity. Finally, a circular ex-situ cell was made and tested with the pure sodium. This modification reduces a rate of degradation of the samples.
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Design and testing of XRD holder for post-mortem analysis of li-ion battery electrodes performed in an inert atmosphere
Klvač, Ondřej ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The work describes the design and manufacturing of a test device for post-mortem measurements of electrodes of electrochemical cells using X-ray diffraction spectroscopy. The theoretical part describes the diffractometer Rigaku Miniflex 600, for which the product is intended. At the same time, an overview of solutions in various applications is processed here in the form of a recherche. The practical part documents the current development of a new cell, on which tests were performed. Here is an overview of the influence of gases and insulating materials on the resulting data, especially distortion and attenuation. Subsequently, a new design with improved hermetic insulation and sample displacement error correction is described. The principle of operation of the manufactured cell, including the control unit and software, is elaborated in the form of technical documentation. Finally, the functionality is verified by comparing the diffractograms of the powder standards and the graphite electrodes.
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