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A Review of the Li-ion Battery in-situ Experiments in Scanning Electron Microscope
Trochta, David ; Klvač, Ondřej ; Kazda, Tomáš
This paper focuses on the description of in-situ experiments with lithium-ion batteries in a scanning electron microscope during cycling. With these experiments, we are able to better understand the working principles and internal processes of Li-ion batteries and improve their efficiency, reliability, and safety based on this knowledge. However, conducting these experiments poses several challenges, which are described in the paper, along with ways in which they can be partially mitigated.
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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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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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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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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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