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Multiscale Modelling of Li-Ion Battery Volume Expansion
Mačák, M. ; Vyroubal, P.
Mechanical characteristics of Li-ion batteries play an important part in the design of electric devices or energy storage systems. Proper mechanical design can increase the safety and the longevity of devices. Apart from external forces, Li-ion batteries also experience internal volume changes due to inherent physical processes, especially volume changes caused by intercalation and deintercalation of lithium ions into electrode materials. Currently, these changes are mainly studied experimentally using complex methods, while numerical simulations of these processes are surprisingly rare. This works presents different numerical approaches for studying internal volume changes in Li-ion batteries. The results show that it is possible to study volume changes at different length scales, but it is necessary to apply a suitable simplification of the model to obtain macroscopic deformation.
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2D structures based on metal phosphonates; relationships between arrangement and properties studied by molecular simulations methods
Škoda, Jakub ; Pospíšil, Miroslav (advisor) ; Čapková, Pavla (referee) ; Praus, Petr (referee)
This work deals with the structural analysis of layered zirconium sulfophenylphosphonates and their intercalates with the use of the classical molecular simulation methods. The inner composition of both fully and partially sulfonated layers was determined in agreement with available experimental data, especially chemical analysis, thermogravimetric measurements and X-ray diffraction. The calculations revealed the positions of the water molecules in the planes of sulfo groups which strongly affect the resultant diffraction pattern. Within the zirconium sulfophenylphosphonate layered structure, the arrangements of intercalated species based on optically active dipyridylamine molecules and cations of sodium, copper and iron were solved with the respect to the agreement with experimental results and values of potential energy. In case of the dipyridylamine molecules and its derivatives, the resultant disordered partially row arrangements of the organic molecules in the interlayer were showed to influence the dipole moment of the intercalate. From this point of view, nitro-derivative has been picked out as the most suitable for potential applications. Regarding the intercalated cations, sodium cations take up the space of water molecules next to the sulfo groups while copper and iron cations are distributed in a...
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DNA/RNA intercalating agents as antivirotics: possible mechanisms of action
Kropáček, Václav ; Španielová, Hana (advisor) ; Šmahelová, Jana (referee)
DNA/RNA intercalating agents are compounds with capability to insert themself between nucleic acids base pairs. This phenomenon is accompanied by structural or functional disruption of said nucleic acid. Some of these compounds are used as therapeutics for cancer, bacterial or parasital infection or are used as antivirotics. This work summarizes different mechanisms which are responsible for antiviral effects of three significant classes of intercalating agents, acridine derivates, quinolines and quinolones. Except for intercalation into nucleic acids, these compounds are also capable of alkalization of cellular organels, inhibition of some viral enzymes (helicase, integrase) and immunomodulation. These abilities enables them to disrupt viral life cycle.
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Ex-Situ Xrd Characterization Of Electrodes For Electrochemical Power Sources
Klvač, Ondřej
The article describes a theoretical method of a research of graphite electrodes in an electrochemical cell where the problem is with the preferred orientation and a thin layer. As a result, only a reflection (002) is visible. However, there is a possibility to determine crystallographic parame-ters from these peaks because of the effect of a destructive and constructive interference caused by intercalated lithium atoms. At the same time, the work shows that Kapton is not a suitable material for ex-situ cell production, as samples have been destroyed by air humidity. Finally, a circular ex-situ cell was made and tested with the pure sodium. This modification reduces a rate of degradation of the samples.
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Design and testing of XRD holder for post-mortem analysis of li-ion battery electrodes performed in an inert atmosphere
Klvač, Ondřej ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The work describes the design and manufacturing of a test device for post-mortem measurements of electrodes of electrochemical cells using X-ray diffraction spectroscopy. The theoretical part describes the diffractometer Rigaku Miniflex 600, for which the product is intended. At the same time, an overview of solutions in various applications is processed here in the form of a recherche. The practical part documents the current development of a new cell, on which tests were performed. Here is an overview of the influence of gases and insulating materials on the resulting data, especially distortion and attenuation. Subsequently, a new design with improved hermetic insulation and sample displacement error correction is described. The principle of operation of the manufactured cell, including the control unit and software, is elaborated in the form of technical documentation. Finally, the functionality is verified by comparing the diffractograms of the powder standards and the graphite electrodes.
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2D structures based on metal phosphonates; relationships between arrangement and properties studied by molecular simulations methods
Škoda, Jakub ; Pospíšil, Miroslav (advisor) ; Čapková, Pavla (referee) ; Praus, Petr (referee)
This work deals with the structural analysis of layered zirconium sulfophenylphosphonates and their intercalates with the use of the classical molecular simulation methods. The inner composition of both fully and partially sulfonated layers was determined in agreement with available experimental data, especially chemical analysis, thermogravimetric measurements and X-ray diffraction. The calculations revealed the positions of the water molecules in the planes of sulfo groups which strongly affect the resultant diffraction pattern. Within the zirconium sulfophenylphosphonate layered structure, the arrangements of intercalated species based on optically active dipyridylamine molecules and cations of sodium, copper and iron were solved with the respect to the agreement with experimental results and values of potential energy. In case of the dipyridylamine molecules and its derivatives, the resultant disordered partially row arrangements of the organic molecules in the interlayer were showed to influence the dipole moment of the intercalate. From this point of view, nitro-derivative has been picked out as the most suitable for potential applications. Regarding the intercalated cations, sodium cations take up the space of water molecules next to the sulfo groups while copper and iron cations are distributed in a...
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Thermal behaviour of organically modified smectites
Plevová, Eva ; Vaculíková, Lenka ; Valovičová, Věra ; Simha Martynková, G.
The smectites were modified with different types of alkylammonium cations. The X-ray powder diffraction was used to calculate the values of the basal space of the modified smectites to confirm the intercalation of cations into the structure. The montmorillonites were also characterized by means of FTIR spectroscopy, which proved sorption or intercalation of the alkylammonium cations too. Thermal behaviour of the smectites was investigated by simultaneous thermogravimetry and differential thermal analysis. The temperatures of dehydratation and dehydroxylation and the temperatures related to total melting and recrystallization generally changed. Study of temperatures changes together with determination of kinetic parameters helped to obtained a comprehensive assessment of smectite thermal stability.
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Negative electrodes for sodium ion batteries
Šátek, Dominik ; Libich, Jiří (referee) ; Máca, Josef (advisor)
This bachelor thesis deals with sodium-ion accumulators with focus on negative electrode, introduces basic terms in the field of secondary cells and describes production of accumulators. The result of this work are tested electrodes based on natural carbon and sodium metatitanate. These electrodes are then compared with each other and evaluated.
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