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Negative Electrode for Sodium-ion batteries
Šimek, Antonín ; Bača, Petr (referee) ; Libich, Jiří (advisor)
This master’s thesis is focused on the research of negative electrode materials for sodium-ion batteries. It contains a general introduction to the issue of batteries, their brief historical development, basic operating principles, key parameters and classification. Attention is paid to lithium-ion batteries, which are the most used technology today. Sodium-ion batteries as their potential replacement, especially in the field of energy storage from renewable sources, are based on lithium-ion technology. Promising candidates for the material for the negative electrode of sodium-ion batteries are sodium titanates. Their synthesis and subsequent electrochemical characterization of electrodes using sodium titanate as the active material are included in the practical part of this work.
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Optimization of Electrode Preparation Technology for Lithium-Ion batteries
Zahálka, Patrik ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This bachelor thesis deals with technological parameters of electrode production proces optimization for lithium-ion batteries. The thesis focuses on the negative electrode based on natural graphite. The first part presents a brief introduction to lithium-ion batteries and current status research. In the theoretical part the thesis focuses on the study of the structural and electrochemical properties of natural graphite and the operating principle of lithium-ion accumulator. The practical part solves optimization of electrode parameters, pressing pressure and electrode layer thickness. The capacitive and current characteristics of electrodes based on natural graphite have been analyzed and compared to the process parameters mentioned above.
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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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Structure and mechanical properties of thin wall nodular iron castings
Chýlková, Adéla ; Mores, Antonín (referee) ; Roučka, Jaromír (advisor)
The purpose of this final thesis is experimental verification of the influence of graphitic inoculants containing different amounts of trace elements on the structure, mechanical properties and internal homogeneity of thin-walled ductile iron casting. This thesis describes the issue with casting of thin-walled ductile iron. Two melts of thin-walled test plates with thickenesses of 3-, 5- and 8 mm were done in experimental part. A total of six types of inoculations with different content of trace elements were tested. Subsequently, an X-ray irradiation analysis was performed on the samples and hardness, tensile strength and ductility were evaluated. Futhermore, the amount of graphite in structure, graphite shape, graphite size, nodularity, graphite nodule count and volume phases of ferrite and perlite in matrix were analysed in thin-walled ductile cast iron by computer-based image analyzer. Finally, the measurement data were processed into tables and charts and conclusions were formulated. An X-ray analysis proved, that all thin-walled test plates containned shrinkage porosity. Furthemore it was confirmed, that content of manganese in inoculant increases tensile strength and hardness. Also content of zirconium in inoculant increases graphite nodule count.
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Recovery Of Anode Material From Lithium Ion Batteries
Báňa, Jiří ; Kazda, Tomáš
As the production of lithium-ion batteries (LIB) is growingat a meteoric pace with the advent of electromobility. There willbe a need for efficient use of recycling processes, which nowfocus mainly on selected metals. Direct recycling is a methodwith great potential due to its simplicity, ecological friendliness,and high efficiency. However, this method needs to be improvedand put into practical use. In this paper, it is focused thesimulation of LIB aging, composition analysis and then recoveryof the anode material of Motoma LFP 18650 and PanasonicNCR18650B batteries.
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Electrochemical etching of graphite tips for potential use in nanoscience
Jonáš, Adam
The main goal is to find an easy, and more importantly, cheap process of producing sharp tips for the potential use in an atomic force microscope (AFM) or as a source of electrons utilizing cold field emission. This objective is being achieved by the method named electrochemical etching, and the used material is cheap and easily accessible. For this experiment, graphite leads of different hardnesses were used, etched with two types of etching solutions. The first solution contained potassium hydroxide (KOH) dissolved in water and the second contained sodium hydroxide (NaOH), also dissolved in water. Different ratios of chemicals were tried for the manufacturing process. Hardnesses of leads were 2B, B, and HB. After the process of etching, products were examined with a scanning electron microscope (SEM). The radius of tips was measured, and results were compared and evaluated. Stating on the output data of tips, it can be said, that goal was achieved, and tips can be used for their potential purpose. There would be needed another research about how well they fit to work.
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In-situ Raman spectroelectrochemistry of graphene and related materials in concentrated aqueous electrolytes
Abbas, Ghulam ; Frank, Otakar (advisor) ; Kunc, Jan (referee) ; Voiry, Damien (referee)
The complex interplay between the material's properties and the electrochemical process often taking place at its ubiquitous edges makes it difficult to discriminate the role of single defects in the charge transfer processes in the material. Therefore, we have performed in-situ μ-droplet Raman spectroelectrochemistry (SEC) to identify the localized charge transfer processes through the basal plane and defects in a selected localized area of 10-20 μm2 of defect-free and defective monolayer graphene. It is noticed that two distinctive electron transfer processes of slower and faster rates exist side-by-side in the same sample but they are confined in the defect-free and defect-rich regions, respectively. Furthermore, in order to explore the electrochemical ion intercalation mechanism for rechargeable batteries, in-situ Raman SEC in a macro SEC cell was performed. It was observed that structural properties such as the lateral domain size (La), degree of graphitization (g), inter-defect distance (LD) and defect density (nD) have substantial influence on the electrochemical (de)intercalation of anion into natural and kish graphite during charge/discharge process. It was also revealed that ultrasound treatment of natural graphite reduces the La which enhances the reversibility of the anion...
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Structure and mechanical properties of thin wall nodular iron castings
Chýlková, Adéla ; Mores, Antonín (referee) ; Roučka, Jaromír (advisor)
The purpose of this final thesis is experimental verification of the influence of graphitic inoculants containing different amounts of trace elements on the structure, mechanical properties and internal homogeneity of thin-walled ductile iron casting. This thesis describes the issue with casting of thin-walled ductile iron. Two melts of thin-walled test plates with thickenesses of 3-, 5- and 8 mm were done in experimental part. A total of six types of inoculations with different content of trace elements were tested. Subsequently, an X-ray irradiation analysis was performed on the samples and hardness, tensile strength and ductility were evaluated. Futhermore, the amount of graphite in structure, graphite shape, graphite size, nodularity, graphite nodule count and volume phases of ferrite and perlite in matrix were analysed in thin-walled ductile cast iron by computer-based image analyzer. Finally, the measurement data were processed into tables and charts and conclusions were formulated. An X-ray analysis proved, that all thin-walled test plates containned shrinkage porosity. Furthemore it was confirmed, that content of manganese in inoculant increases tensile strength and hardness. Also content of zirconium in inoculant increases graphite nodule count.
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Study of the influence of fillers and external conditions on the resistivity of cement composites
Kejda, Dalibor ; Melichar, Jindřich (referee) ; Černý, Vít (advisor)
The progress of new materials is important for the construction industry. Modern materials include cement composites with reduced resistivity. This is achieved by adding suitable electrically conductive fillers. If there is enough of these fillers, the so-called percolation threshold occurs. Suitable fillers (Condufit C4 and Supragraphite C300) have been proposed. Recipes have been designed to be before and after the percolation threshold. The tests were performed on beams measuring 40x40x160 mm with built-in electrodes for measuring their resistivity. The aim of the work was the research of influencing external conditions on cement composites. The effect of temperature was verified. The lowest values of resistivity were evaluated at temperatures of 50 ° C and the resistivity increased with decreasing temperature. The effect of humidity on the resistivity was then verified. Reference samples and samples with a smaller proportion of graphite powder showed larger differences in resistivities with increasing humidity. The samples above the percolation threshold were not much affected by increasing humidity. Finally, the effect of loading on the resistivity of the samples was verified. Almost all samples with increasing compressive stress showed an increasing value of resistivity.
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