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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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Materials and Components for Lithium-Ion Power Sources
Jirák, Tibor ; Kadlec, Jaromír (referee) ; Paidar,, Martin (referee) ; Vondrák, Jiří (advisor)
The dissertation thesis deals with electrode materials and components for lithium-ion power sources. The thesis works with two different kinds of materials, concretely nanostructured Li4Ti5O12 with spinel basis and LiCoO2 with layered structure. The electrochemical properties, structure and element analysis and utilization possibilities in electrochemical industry of new technological electrode material Li4Ti5O12 were investigated. The influences of admixtures and electrolytes on characteristics of electrode materials with aforesaid active masses were also examined. Low cost price, environmental safety and obtained results of electrochemical measurements and structure analysis refer to wide possibilities of usage electrode material Li4Ti5O12 in the field of electrochemistry.
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Modification of Cathode Materials for Lithium-Ion Accumulators
Kazda, Tomáš ; Studničková, Marie (referee) ; Vanýsek, Petr (referee) ; Vondrák, Jiří (advisor)
This doctoral thesis deals with properties of cathode materials for Lithium-Ion accumulators. The theoretical part consists of an overview of the cathode materials and a brief introduction into the very wide area of Lithium-Ion accumulators. The goal of this work was to study the LiCoO2 cathode material and to prepare some modifications of it by doping with other elements. This work was then extended with the study of the new generation of high-voltage cathode materials. The aim of this part was to study their synthesis, their physical and electrochemical properties and the influence of used electrolytes on their electrochemical stability. The work then focuses on the influence of doping these materials and the influence of another part of the battery – the separator – on the overall properties of these types of cathode materials. The results show that doping the LiCoO2 cathode material with sodium and potassium lead to an enhancement of some electrochemical properties as stability during cycling or stability at higher loads and also the long-term stability during aging is better. The LiNi0,5Mn1,5O4 high voltage material was synthetized in both its forms in comparable or even better quality compared with the results from foreign laboratories. The synthesis process was watched in-situ by SEM, thanks to which a unique study of the ongoing changes during synthesis was done. Also the best suitable electrolytes for this material were identified from the viewpoint of stability at high voltages, which is important for the future practical use. Doping of the material with chromium resulted in better stability and capacity both during cycling at standard conditions and at higher temperature and load. A significant impact of the separators on the overall electrochemical properties of the cathode materials was proved, which could be a big benefit for their future usage.
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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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Modification of cathode material based on nickel and manganese for Li-ion cell
Bukáčková, Ivana ; Vondrák, Jiří (referee) ; Kazda, Tomáš (advisor)
This bachelor´s thesis deals with cathode materials for lithium batteries with cell voltage approaching 5V. The first part of the thesis is devoted to the characteristics of Li-ion batteries, electrochemical reactions and properties of electrode materials. She also pays attention to the preparation and measurement of materials LiNi0,5Mn1,5O4, LiNi0,45Mn1,55O4 and LiNi0,55Mn1,45O4. Observed material was measured by electron microscopy, elemental analysis and galvanostatic method,
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Electrode materials based on lithium titanate oxide for lithium-ions accumulators
Kaválek, Ondřej ; Vondrák, Jiří (referee) ; Jirák, Tibor (advisor)
The bachelors thesis deals with researching electrode materials based on Li4Ti5O12 for lithium-ions accumulators. The work is divided into two areas – teoretical and practical part. Teoretical part is aimed at electrochemical power sources with focusing on lithium-ions accumulators. Consenquetial part is concentrated on electrochemical processes and analysis of researching samples Li4Ti5O12. Observed material was measured by galvanostatic method, cyclic voltammetry, impedance spectroskopy and electron microscopy. Aim of the work was obtaining characteristics of electrode material and finding out usability of the material in lithium-ions accumulators.
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Study of stability of electrolytes and electrodes by electrochemical methods
Bukáčková, Ivana ; Čech, Ondřej (referee) ; Kazda, Tomáš (advisor)
This master´s thesis deals with stability of electrolytes and electrodes using electrochemical methods of Li-ion batteries. The first part of the project is devoted to the characteristics of Li-ion batteries, electrochemical reactions and characteristics of electrode materials. Consenquetial part is concentrated on preparation and measurement of elektrolyte EC : DMC with 1M LiPF6. The elektrolyte was investigated using galvanostatic method, cyclic voltammetry and impedance spectroscopy.
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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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Synthesis of Perspective materials for cathodes of Li-ion batteries with low cobalt content
Hálová, Hana ; Kazda, Tomáš (referee) ; Chladil, Ladislav (advisor)
The thesis is focused on cathode materials with low cobalt content. In the work, there is a comparison of cathodes with cobalt, low cobalt content, and without it. The materials are compared in terms of theoretical specific capacity, commonly achieved specific capacity within first cycles, energy density, and cycle life. Taking into account these criteria there have been selected perspective high voltage cathode materials. For selected cathode materials, various synthesis options were compared, with spray-drying synthesis chosen for the research conducted within the experimental part of the thesis. The thesis also describes the preparation of a laboratory apparatus for spray-drying synthesis, including a particle capture system. Furthermore, systematic experiments were carried out to optimize the high-temperature calcination process.
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Study of stability of electrolytes and electrodes by electrochemical methods
Bukáčková, Ivana ; Čech, Ondřej (referee) ; Kazda, Tomáš (advisor)
This master´s thesis deals with stability of electrolytes and electrodes using electrochemical methods of Li-ion batteries. The first part of the project is devoted to the characteristics of Li-ion batteries, electrochemical reactions and characteristics of electrode materials. Consenquetial part is concentrated on preparation and measurement of elektrolyte EC : DMC with 1M LiPF6. The elektrolyte was investigated using galvanostatic method, cyclic voltammetry and impedance spectroscopy.
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