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Dynamic in-situ experiments utilizing probe microscopy
Patočka, Marek ; Frank, Otakar (referee) ; Kolíbal, Miroslav (advisor)
V této práci je uvedeno několik případových studií dynamických in-situ experimentů s využitím skenovací sondové mikroskopie. Nejprve je zkoumána elektrodepozice lithia v baterii s pevným elektrolytem bez kladné elektrody. Na tento experiment navazuje obdobné měření, při kterém jsou jako materiál kladné elektrody použity částice MXene. Druhá část práce se zabývá grafenem plovoucím na kapalném kovu. Je zde prezentováno zkoumání přítomnosti menisku okolo grafenových vloček.
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Design of a measurement circuit for electrochemical cells cycling in SEM chamber
Tran, Quoc Bao ; Trochta, David (referee) ; Klvač, Ondřej (advisor)
This diploma thesis deals with the design of a measurement circuit consisting of two separate modules for measuring electric current in the order of nanoamperes (nA) for the in-situ analysis of lithium-ion cells in microscopic dimensions. The aim of this thesis is to build a prototype measurement circuit to solve the electromagnetic interference (EMI) problems associated with in-situ analysis and to perform subsequent testing of this circuit or modules. The diploma thesis is divided into two parts, namely a theoretical and an experimental part. In the theoretical part, research on electrochemical cells is described, where the focus is directed towards lithium-ion cells. The principle of the function of these cells is described and research on their degradation mechanisms has also been carried out. Furthermore, the testing methods of lithium-ion cells such as GCPL, OCV and CV have been described. In the theoretical part, the in-situ experiments already performed at Thermo Fisher Scientific Brno are described. One experiment consisted of assembling an electrochemical cell on a MEMS chip and the other experiment was performed using a micromanipulator as a current collector. Measured data were affected by electromagnetic interference. The practical part discusses the design of a measurement circuit that would theoretically solve the problems of measuring very small currents from an EMI perspective. It also describes how the measurement circuit was tested.
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Using of X-ray for distribution analysis of electrodes for secondary cell application
Macháč, Milan ; Bača, Petr (referee) ; Chladil, Ladislav (advisor)
This diploma thesis is focused on in-situ analysis of the composition of the negative electrodes of second secondary cells with using X-ray radiation. The first part is dedicated to the theory of lead accumulators, including charging, discharging, battery components and individual degradation mechanisms. The main part of the thesis includes the preparation of electrochemical in situ XRD cells and following measurement of the growth of lead sulphate crystals on the OCV potential. Furthermore, the lead cell was subjected to the measurement of the cyclic voltammetry around the working point of the negative electrodes. From these measurements was evident gradual increase of the lead sulfate crystals. The analysis was supplemented with electron microscopy images. In addition, were evaluated the in-situ particle analysis of the LTO Sigma sample.
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The Study of ZnO Crystal Growth in Supersaturated Alkaline Solution
Bannert, Tomáš ; Máca, Josef (referee) ; Chladil, Ladislav (advisor)
This thesis deals with the study of growth of zinc oxide crystals from supersaturated solutions using a scanning electron microscope and XRD methods. The work is divided into a theoretical and an experimental part. The theoretical part analyses issues related to the principle of operation of electrochemical cells with an emphasis on Ni-Zn batteries and phenomena limiting the life and efficiency of Ni-Zn batteries with a focus on phenomena that affect precipitation processes of zinc oxide crystals. It also analyses and compares the appropriateness of the methods that have been used to study the growth of the prepared zinc oxide crystals. The experimental part describes the preparation of a supersaturated solution, the process of each analysis and its evaluation. The results of each method are compared with the theoretical assumptions and among themselves. The experimental part also contains a chapter dealing with the design of in situ X-ray diffraction analysis methods of the obtained zinc oxide crystals.
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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 adaptation of electron microscope accessories for in-situ experiments
Drozd, Michal ; Mikulík, Petr (referee) ; Kolíbal, Miroslav (advisor)
Účinnost katalyzátoru v kombinaci s optimalizovanou reakcí a minimalizováním jeho množsví jsou klíčovými faktory při snižování investičních a provozních nákladů v rámci chemických procesů. Díky pokročilým experimentálním technikám mohou být katalyzátory dále zlepšovány. Jednou z těchto technik je in-situ elektronová mikroskopie. Tato práce se zabývá vývojem zařízení pro automatický ohřev vzorku, automatickým vpouštěním reaktantů a měřením parciálních tlaků v komoře mikroskopu. Dále je pomocí provedených experimentů srovnán přístup pomocí environmentálního rastrovacího mikroskopu, kde se využívá laserový ohřev vzorku s přístupem, který využívá skenovací elektronový mikroskop připojený k ultra vakuové komoře, kde se vzorek zahřívá pomocí průchodu elektrického proudu.
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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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Preparation and properties of silver nanoparticles on collagen matrix
Konečná, Zuzana ; Chamradová, Ivana (referee) ; Vojtová, Lucy (advisor)
Cílem předložené diplomové práce byla in-situ příprava stříbrných nanočástic na kolagenové matrici jako antibakteriálního povlaku a studie vlivu podmínek přípravy na vlastnosti nanočástic, zejména jejich velikost, tvar, homogenita jejich distribuce a antibakteriální aktivita. V rámci práce byla rovněž sledována kinetika redukce stříbrných nanočástic z dusičnanu stříbrného a vliv teploty na její průběh. Připravený materiál a jeho vlastnosti byly analyzovány pomocí různých technik. UV-VIS absorpčních vlastností stříbra bylo využito pro kinetické studie redukce a uvolňování nanočástic. Pomocí rastrovací elektronové mikroskopie byla vyhodnocena homogenita stříbrného povlaku a přibližná velikost částic a jejich aglomerátů. Velikostní distribuce nanočástic byla pak přesně stanovena pomocí dynamického rozptylu světla. Pomocí infračervené spektrometrie s Fourierovou transformací s technikou úplného zeslabeného odrazu byla sledována interakce stříbra s funkčními, zejména karboxylovými skupinami. Termogravimetricky byla stanovena tepelná stabilita a procentuální obsah stříbra v materiálu. Vliv AgNPs povlaku na 3D strukturu kolagenního scaffoldu a fázový kontrast pro 3D zobrazovací techniky byl zkoumán pomocí rentgenové výpočetní nanotomografie. V neposlední řadě byla také stanovena antibakteriální aktivita připraveného materiálu a její závislost na koncentraci stříbra.
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Recrystallization study of free-cutting steel by in-situ SEM/EBSD technique
Babinský, Tomáš ; Němec, Karel (referee) ; Petrenec, Martin (advisor)
Placing recrystallization annealing in a manufacturing proces is often necessary in order to restore plasticity of worked blanks right before working products to its final shape. For better understanding of processes which are taking place in a material during annealing the use of in-situ techniques is favorable. Such observations enable us to watch changes in the materiál in real time at the original spot. Observations at grain-level are ideally made with scanning electron microscope – SEM by electron back-scattered diffraction – EBSD. The technique makes watching nucleation, growth and potential coarsening of recrystallized grains possible. Special construction of a tensile stage allows us to watch changes of a sample during tensile tests which can be used in observing influence of MnS inclusions on plasticity of free-cutting steels. Materials studied in this work are commonly used free-cutting steel 11SMnPb30 and its lead-free alternative 11SMnBi30.
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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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