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The influence of ionic liquids on functional elements in lithium-ion batteries
Meščánková, Veronika ; Sedlaříková, Marie (referee) ; Máca, Josef (advisor)
This thesis deals with ionic liquids, their conductivity and the action of the electrode materials, separators and current collectors. The theoretical part is focused on the properties of ionic liquids, Li-ion batteries, corrosion, conductivity and analysis elements. The practical part is focused on the production of graphite electrodes, measuring the conductivity of ionic liquids with different parts of lithium – ion battery and measuring the potential window. Also, there is the effect of ionic liquids described in these parts.
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Minimizing errors in measuring ultra low currents
Maule, Radek ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
This work describes the methodology of measuring ultra low currents of the order of 10-8-10-14 [A] and the errors that arise during the measurement. This work is focused on electrical conductivity of insulation materials and interfaces electrode - dielectric during charging and discharging of the sample which is located in the ideal workplace.
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Local electrical conductivity measurements in AFM tapping mode
Dao, Radek ; Konečný, Martin (referee) ; Pavera, Michal (advisor)
This bachelor thesis is concerned about the development of a probe for local electrical conductivity measurements in tapping mode Atomic Force Microscopy. The teoretical part gives a short overview of Scanning Probe Microscopy techniques, with the focus being on Conductivity Atomic Force Microscopy. Furthermore, the measuring regime in which the probe operates is described here, as well as the basic component of the probe, the quartz tuning fork. The experimental part follows the iterative development process, and contains a chapter dedicated to making of very sharp tips. The final chapters describe the preparation of test samples, which were used to prove the functionality of the probe and the measurement of local electrical conductivity itself.
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Synthesis and characterization of sulfurized polymers for electrochemical power sources
Svoboda, Lukáš ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
Batteries based on lithium-sulfur technology have the potential to increase the amount of stored energy in comparison with current lithium-ion systems while maintaining the same weight. Achieving this goal is possible due to the high theoretical energy density of sulfur, which exceeds the values of other materials used in batteries. However, these batteries suffer from several failing, which still hinder the practical use. The use of amorphous sulfur instead of its crystalline form might lead to increasing of durability and charge efficiency. Inverse vulcanization of sulfur seems to be the perspective method for the preparation of polymer sulfur because it prevents its recrystallization and stabilizes amorphous sulfur. The aim of this thesis is the preparation and study of properties of materials made of inverse vulcanized sulfur.
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Insulation and dielectric properties of water
Grill, Jiří ; Frk, Martin (referee) ; Špinka, Jiří (advisor)
This master´s thesis deals about insulation and dielectric properties of water. It describes the structure of water, covalent and hydrogen bonds. It outlines primary chemical and physical properties of water and then it describes parameters of water - dynamic viscosity, conductivity, surface tension, pH and also describes dielectric properties - dielectric loss, loss factor, permittivity, polarization. Part of the work is practical section, which includes measurements of deionized water, destilled water, tap water and shows primary dependence such as dependence loss factor on frequency or relative permittivity on frequency.
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Study of sensoric properties of organic semiconductors
Saska, Pavel ; Šedina, Martin (referee) ; Salyk, Ota (advisor)
Compounds based on diketopyrrolopyrrole are organic pigments that behave as semi-conductors. Their analogues with pyridyl side group are due to their sensitivity to hydrogen potentially useful as hydrogen sensors. The aim of this work was to examine properties of sensors with an active layer of diketopyrollopyrolle derivatives. The sensors were tested on an apparatus built for this purpose at FCH VUT in Brno. More specifically, changes to conductivity of these sensors in the presence of hydrogen under various conditions were studied.
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Preparation and characterization of plasma activated water
Lemonová, Hana ; Klímová, Edita (referee) ; Krčma, František (advisor)
This bachelor thesis deals with suitable methods for plasma activated water preparation. The plasma activated water is a new way of the indirect plasma application for the treatment of biological materials like food or even for the direct application for therapeutic purposes. The theoretical part is focused on getting acquainted with plasma activated water and methods for its preparation, using various plasma systems. The detailed description of the plasma-liquid systems used during this thesis is given later. The selected physical chemical properties, namely conductivity, pH value and stability of hydrogen peroxide are presented in the results part. An important aspect of this work was to find suitable storage conditions for plasma activated water.
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New gel electrolytes
Sumka, Martin ; Jahn, Michal (referee) ; Sedlaříková, Marie (advisor)
This master´s thesis deals with the properties of gel polymer electrolytes, brief characteristics of other types of electrolytes and materials that are used for preparing polymer electrolytes. The thesis explains the use of the gel electrolytes in practice, the current conduction in the electrolytes and the properties of ionic liquids, and flame retardants. This thesis also focuses on methods of measurement of mechanical properties of gel polymer electrolytes. The practical part is focused on preparation of methacrylate gel electrolytes and their modifications with the use of flame retardant - triethyl phosphate (TEP) and ionic liquid - 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (Emim TFSI). In this part there are evaluations of their potential funcionality (potential window) and specific conductance conductivity using the method LSV (linear sweep voltammetry) and impedance spectroscopy. The practical part also includes a thermal analysis of selected samples by TGA, DTA and EGA methods.
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