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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 electrode materials for post-lithium ion systems
Kekelák, Miroslav ; Jaššo, Kamil (referee) ; Kazda, Tomáš (advisor)
This bachelor thesis deals with studying electrode materials for post-lithium ion systems. The theoretical part describes the principle, history and construction of lithium-ion battery cells. A separate chapter is dedicated to the materials of positive and negative electrodes for lithium-ion batteries. The third chapter is dedicated to the principles of new generation lithium-air and sodium-ion batteries. The last chapter of theoretical part is dedicated to lithium-sulfur batteries, which describes their principle, history, used electrode materials and the influence of binders. The experimental part is dedicated to the preparation of the electrode material of lithium-sulfur accumulator in combination with water-soluble binders and their measurement using electrochemical methods.
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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 electrode materials for post-lithium ion systems
Kekelák, Miroslav ; Jaššo, Kamil (referee) ; Kazda, Tomáš (advisor)
This bachelor thesis deals with studying electrode materials for post-lithium ion systems. The theoretical part describes the principle, history and construction of lithium-ion battery cells. A separate chapter is dedicated to the materials of positive and negative electrodes for lithium-ion batteries. The third chapter is dedicated to the principles of new generation lithium-air and sodium-ion batteries. The last chapter of theoretical part is dedicated to lithium-sulfur batteries, which describes their principle, history, used electrode materials and the influence of binders. The experimental part is dedicated to the preparation of the electrode material of lithium-sulfur accumulator in combination with water-soluble binders and their measurement using electrochemical methods.
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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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