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Preparation and characterisation of electrode materials based on elementar sulphur for Li-ion cells
Jankulár, Tomáš ; Vondrák, Jiří (referee) ; Čech, Ondřej (advisor)
This thesis deals with the preparation and characterization of electrode materials for Li-ion batteries based on elemental sulfur. The theoretical part is focused on the characteristics of Li-ion batteries, electrochemical reactions, the process of electrochemical lithiation of sulfur and solubility properties of intermediate polysulfides. The practical part of the thesis deals with the preparation of cathode materials for Li-ion cells with an active substance in the form of elemental sulfur. The prepared electrodes were investigated using cyclic voltammetry and galvanostatic cycling. Physical characterization by SEM and XRD was provided.
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Causes of Premature Capacity Loss of Lead-Acid Accumulators Operating in PSoC Mode in Hybrid Electric Vehicles
Bilko, Radek ; Jareš, Petr (referee) ; Dostál, Zdeněk (referee) ; Bača, Petr (advisor)
This thesis is completion of whole stage of researches and it is a result of existing need of increase efficiency, utilization rate and service life of lead acid batteries VRLA planned for utilization in hybrid electric vehicles in mode of partial state-of-charge PSoC. During the application of mode PSoC at lead acid battery occurs irreversible sulfation of negative electrodes and thus to loss their charging capability. This phenomenon, according to the latest trend called PCL3, isn´t connected with subsequently referred effects PCL1, PCL2, show up on positive electrodes. Result of this thesis is finding a new types of additives, determine their optimum amount and size in such a way that innovated composition of negative active materials be able to resist sulfation of negative electrode during operation in mode PSoC. Part of the effort to clarify actions ongoing on negative active material and causes non-returnable sulfation electrodes is also monitoring of structural changes electrode active material by using environmental scanning electron microscope, which helped to clarify processes related with loss of capacity in mode PSoC. Special attention during reserches was focused on study of the properties contact layers between collector and electrodes active material and itself active materials lead-acid battery druring exploitation. There were gain new information about influence repeated cycling of (charging, discharging) the critical area of the electrodes. Measurements was carried out on specially prepared experimental electrodes DC Difference Method, this enabled obtain data in situ.
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Positive electrode for lůithium-ion batteries based on LiCoO2
Krištof, Petr ; Kazda, Tomáš (referee) ; Sedlaříková, Marie (advisor)
This diploma thesis deals with materials used by production ofcathodes of Lithium-ion batteries. Primary this thesis deals with LiCoO2material and its subsidizing of alkali metals. The first part deals with the charakteristic of Lithium-ion batteries, used materials, possibilities of doping and charging. The practical part concentrates on production of active substance of cathode and doping this substance by sodium and potassium. The methods of evaluation were used galvanostaticcycling and x-ray analysis (XRD).
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Study of manganeese oxides properties by the EQCM method
Pléha, David ; Špičák, Petr (referee) ; Novák, Vítězslav (advisor)
The present work deals with the use of manganese oxide as a catalyst for positive electrode of fuel cells. The theoretical part is to analyze the problem of fuel cells, focusing on lowtemperature fuel cells. Are discussed and the methods of measurement and evaluation of properties of manganese oxide layer. The practical part deals with doping electrolytic manganese dioxide salts of divalent metals and monitoring their behavior in the cyclic voltammetry by the EQCM method.
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Study of influence of admixtures on electrochemical characteristics electrode materials for lithium-ion batteries
Nejedlý, Libor ; Jirák, Tibor (referee) ; Sedlaříková, Marie (advisor)
The bachelor project deals with new intercalation materials with admixtures for positive electrode of lithium-ion accumulators. Concretely, the project works with new preparation methods of electrode materials and compares them with long-established industrial process. For this purpose were used electrochemical measurements and structure analysis obtaining materials. The theoretical part of the project is devoted summary of electrochemical power sources, electrochemical reactions, recycling and future of Li-ion batteries. The practical part describes electrochemical methods, measurements and discusses achieved results.
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Study of materials for the Li-ion batteries by electron microscopy
Hujňák, Jan ; Čudek, Pavel (referee) ; Kazda, Tomáš (advisor)
This work deals with problems of lithium-ion batteries. In the theoretical part are described electrochemical sources in general and their division. The main representatives of individual types of electrochemical sources are described in more detail. In the next part the thesis focuses specifically on lithium-ion accumulators, their history, electrochemical reactions taking place inside and materials of individual parts of which the accumulator consists. Next part focuses on electron microscopy and its division into scanning and transmission. Basic parts and the principle of operation are described. The practical part is focused on creating a small cell for examination under an electron microscope.
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Composite electrode materials for lithium-ion batteries based on LiFePO4 prepared using GAC method
Vilhelm, Ondřej ; Neoral, Jiří (referee) ; Čech, Ondřej (advisor)
Presented work investigates the problem of secondary lithium-ion cells and the different available cathode materials. We have prepared samples of LiFePO4 with the addition of different kinds of carbon materials such as Super P, Vulcan and expanded graphite. We have always created the sample with and without surfactant. Developed samples were compared by measuring electrochemical methods (cyclic voltammetry, charge and discharge cycles and impedance spectroscopy). We also modeled the three-point cell for measuring electrochemical electrode materials.
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Electrodes for lithium-ions batteries based on LiCoO2
Nejedlý, Libor ; Čech, Ondřej (referee) ; Sedlaříková, Marie (advisor)
This master´s thesis deals with electrodes for lithium-ions batteries based on LiCoO2. The first part of the project is devoted to the characteristics of Li-ion batteries, electrochemical reactions and characteristics of electrode materials. The next part describes an experiment that deals with the effects of NA doping on performance of layered materials for lithium secondary batteries. The materials were measured by cyclic voltammetry, impedance spectroscopy and galvanostatic cycling.
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