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Inverse vulcanised sulphur as an electroactive material for lithium-sulphur and sodium-sulphur batteries
Trochta, David ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
This thesis deals with the study of lithium-sulfur and sodium-sulfur batteries, which are designed for use at room temperatures. Both of these systems are interesting mainly due to their high theoretical capacity and low environmental impact, thus greatly outperforming lithium-ion batteries. The weakness of these new technologies is their low lifespan and the associated rapid loss of battery capacity. To increase the lifespan, elemental sulfur in this work was replaced by sulfur with an amorphous structure, synthesized by an inverse vulcanization process that has been optimized in various ways. In addition to the optimization of the inverse vulcanization technology window, the effect of the addition of carbonaceous additives during the synthesis was also investigated. In this work, a series of samples of inverse vulcanized sulfur with different ratios of input precursors were prepared and also with different additives. X-ray diffraction was used to confirm the amorphous structure of the material, which also excludes the presence of crystalline sulphur. The results of Raman spectroscopy were also presented, demonstrating the possibility of using this method to determine semi-quantitative ratios of the input precursors. Electrodes for electrochemical cells were fabricated from selected samples. The homogeneity of the distribution of the electroactive material on the electrode was investigated using a scanning electron microscope and elemental mapping by energy dispersive spectroscopy technique. The electrochemical characterization of the inversely vulcanized sulfur electrodes was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic potential limited cycling.
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Tesla's turbine as a source of energy
Šedina, Martin ; Libich, Jiří (referee) ; Kazda, Tomáš (advisor)
The bachelor thesis deals with the currently used types of water turbines and next part of the thesis deals with the theory of Tesla turbine. The theoretical part discusses water wheels, water turbines with their types and models which are described in the work. The thesis also discusses the construction of the Tesla turbine, its possibilities of using, inside principles and information about Tesla´s patent. The practical part contains the design of the Tesla turbine with modifications for increasing efficiency. The thesis describes the technology that the turbine was produced.
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Proposal for the Creation of an Investment Portfolio of a Fund of Qualified Investors
Kazda, Tomáš ; Brauner, Roman (referee) ; Rejnuš, Oldřich (advisor)
The subject of the bachelor's thesis is the elaboration of a proposal for an investment portfolio of a fund of qualified investors focused on gold mining companies. For this purpose, a model fund is created and it is made a selection of companies according to its statute. After that the companies are analyzed, verified and finally compared to determine the final ratio of individual companies in the fund. At the end of the work, a proposal for the management of the fund with the recommended composition of its portfolio is compiled.
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Design of sheet bender
Kazda, Tomáš ; Tůma, Jiří (referee) ; Pavlík, Jan (advisor)
This bachelor’s thesis deals with the design of a sheet metal bending machine, which is intended for home workshops, or common craft operations. The first part of the thesis contains a overview of similar machines, that are currently available in the shops. In the second part of the thesis was selected the most optimal design, which arose from the three conceptual designs. Each design was rated and on the basis of a multi-criteria analysis were selected the best one. Final design were processed to the 3D model, which have a technical calculations and technical drawings too. After this were made a economic calculations of a final design, including a comparison with a selected models from the research part of this thesis.
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Low temperature Fuel Cells
Kazda, Tomáš ; Novák, Vítězslav (referee) ; Barath, Peter (advisor)
The Bachelor’s thesis is aimed at the low-temperature fuel cells and their usage in cars and mobile applications. In the theory part of this project is described the evolution of the fuel cells in last years and historically as well. Further there are described their functions and particular kinds of the fuel cells with aim at low-temperature cells. In the practical part of this thesis we were making different kinds of carbon mixtures. We have been doing measurements of mixtures on rotate disk electrode and in the experimental fuel cell. At the end of the work are experimentally evaluated different types of carbon materials with different contents of platinum depositing. The results are evaluated using electro analytical methods, using this evaluation to optimize the composition of the material used as electrode material in fuel cells.
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Comparison of different types of commercial lithium-ion batteries
Šindelářová, Anna ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
The master's thesis is devoted to the comparison of different types of lithium-ion batteries. Primarily, an introduction to electrochemical power sources and their division is described. Furthermore, the thesis deals only with lithium-ion batteries. In the theoretical part, the chapters discuss the history, the principle of operation and a detailed description of the main battery parts, including used materials. A comparison of commercially available lithium-ion cells with each other as well as with other types of batteries is also included in the theoretical part. The practical part deals with the cyclinf of lithium-ion cells and subsequent evaluation of the effect of temperature on the capacitance and current characteristics of these lithium-ion batteries.
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