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The study of the electrical and dielectric properties of gas sensors based on ionic liquids
Maráčková, Lucie ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This diploma´s thesis is focused on a study of electrical and dielectric properties of gas sensors based on ionic liquids. Measurements were done on two different types of OECT substrates (0099 and 0160). Three ionic liquids and physiological solution PBS were chosen as electrolytes. Direct current current-voltage characteristic was measured. Switching rations of transistors with this electrolyte were determined by current-voltage characteristic. Alternating resistivity dependence on frequency were measured as well. Better properties showed OECT 0099 substrates.
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Applications of ionic liquids in electrolytes for amperometric gas sensors and Li-ion batteries.
Nádherná, Martina ; Opekar, František (advisor) ; Samec, Zdeněk (referee) ; Zima, Jiří (referee)
Mgr. Martina Nádherná PhD. Thesis Applications of ionic liquids in electrolytes for amperometric gas sensors and Li-ion batteries SUMMARY The dissertation presents the results of preparation and characterisation of new aprotic electrolytes based on ionic liquids for the solid-state electrochemical gas sensors and for the electrochemical energy storage devices - secondary lithium-ion batteries. In the part dealing with the solid-state amperometric sensor for NO2 research was aimed at development of new solid electrolyte. This electrolyte is developed as a system of ionic liquid embedded in the structure of a polymer, when the ionic liquid joints the properties of a solvent and a dissolved salt. The electrolyte therefore does not contain any volatile component and is long-term chemically and electrochemically stable. Several series of electrolytes were prepared with different polymers or macromonomers and imidazolium-based ionic liquids. The composition, especially the polymer-IL ratio was optimized. The electrolytes were successfully tested in a solid-state NO2 sensor with a gold minigrid serving as the indicating electrode. The research included the determination of basic electrochemical parameters and study of the sensor behaviour under different conditions. The influence of atmosphere humidity,...
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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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Ionic liquids for electrochemical power sourcees
Korec, Pavol ; Máca, Josef (referee) ; Sedlaříková, Marie (advisor)
Bachelor thesis Ionic liquids for electrochemical power sources deals with the measurement of electrical properties of ionic liquids, their conductivity and potential window, to broaden the knowledge of their optional use as lithium – ion battery electrolytes. The theoretical section of the work deals with the properties and usage of ionic liquids, structure and functionality of lithium – ion batteries and measurment of electrochemical impedance spectroscopy a cyclic voltammetry. The practical section of the work describes the process of measuring the conductivity and potential window of ionic liquids, observes the changes made to the electrical properties of the samples by adding LiBF4 salt and propylencarbonate solvent and summarizes results.
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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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Electrodeposition of thin tantalum layers from ionic liquids and measurement of their electrical properties
Svobodová, Ivana ; Boušek, Jaroslav (referee) ; Šimůnková, Helena (advisor)
The thesis is focused on the electrodeposition of tantalum from ionic solution 1-butyl-1- methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, ([BMP]Tf2N) at 200°C and description of related transfer and kinetic phenomena on the interface between the ionic solution and working electrode. Furthermore, the electrodeposition of tantalum layers in different ionic solutions containing tantalum salts and especially in ([BMP]Tf2N) is introduced. In the last part of the thesis, results of cyclic voltammetry, surface analysis SEM and elemental analysis EDX are discussed. MIS (metal-insulator-semiconductor) structure was determined comprising porous anodic alumina as the insulator and semiconductive TaxOy on the top of the insulator. The electric conductivity of the MIS structures was studied by using amper-volt IV and CV characteristics. The results of the cyclic voltametry, impedance spectroscopy and chronoamperometry are discussed.
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Study of optoelectrical properties of organic semiconductor thin film layers of phtalocyanines
Miklíková, Zdeňka ; Vala, Martin (referee) ; Zmeškal, Oldřich (advisor)
Diploma thesis is focused on the study of optoelectric properties of thin layers of organic materials based on phthalocyanines, which can be used as an active layer of photovoltaic cells. Especially are studied the properties of the thin active layers of PdPc and PdPc + IL on the glass or ceramic substrates with aluminium contact, which are prepared by material printing here. On the prepared samples were first measured current-voltage characteristics in the dark and in the light and then were measured impedance spectrums in the dark. The received results will be used to improve the properties and structures of photovoltaic cells.
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Study of electrical and dielectric properties of ionic liquids
Maráčková, Lucie ; Nešpůrek, Stanislav (referee) ; Zmeškal, Oldřich (advisor)
This bachelor´s thesis is focused on a study of electrical and dielectric properties of ionic liquids in the form of solution and thin layers. The values of breakdown voltage have been determined from current-voltage characteristics in solutions. Frequency dependencies have been also observed and used for calculation of values of parallel conductivity and capacity of ionic liquid. It was found that solutions is contained by model with one parallel combination of conductivity and capacity. Thin layers have been created by mixing up PEDOT:PSS with two ionic liquids: 1-butyl-3- methylimidazolium trifluoromethanesulfonate and 1-ethyl-3-methylimidazolium tetrafluoroborate. These layers have created electrochemical battery as is evident from current-voltage characteristics. Frequency dependencies are more complex, a model contained two or respectively three parallel conductivities and capacities which have been influenced by PEDOT:PSS and by ionic liquids characteristics.
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