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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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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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Gel polymer electrolytes modified by ionic liquids with aprotic solvents
Pospíšilová, Michaela ; Sedlaříková, Marie (referee) ; Jahn, Michal (advisor)
This graduate thesis is focused on measuring the electrical conductivity of the gel polymeric electrolytes, their preparation and deals with the changes of the performance ratio of the individual substances in gel electrolyte The theoretical part deals with electrochemistry, gel electrolytes, the conductivity of electrolytes, gel electrolytes preparation, methods used to evaluate the measured results and on the properties of the ionic liquids. In the practical part is summarized the process of preparing gel electrolytes, the chemicals to prepare the gels with ionic liquids. The results are evaluated by using impedance technique and linear voltammetry, there are calculated the values of the electrical conductivity of the electrolyte and potential windows.
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Study of Electric and Dielectric Properties of Ionic Liquids
Altšmíd, Jakub ; Boušek, Jaroslav (referee) ; Mikula, Milan (referee) ; Nešpůrek, Stanislav (advisor)
Dizertační práce je zaměřena na studium elektrických a dielektrických vlastností iontových kapalin. Iontové kapaliny mohou nacházet uplatnění v široké škále aplikací, především pak v elektrotechnice. Teoretická část se věnuje popisu základních vlastností iontových kapalin a možností jejich uplatnění v kondenzátorech a elektrochemických senzorech plynů. Experimentální část se věnuje použitým metodám charakterizace vlastností iontových kapalin, jsou zde popsány teoretické poznatky o dielektrické spektroskopii včetně metod stanovení fyzikálních vlastností a vyhodnocení experimentálních dat. Experimentální část je rozdělena na dvě základní části. První se věnuje studiu iontových kapalin pro použití jako elektrolytu v kondenzátorech, druhá část se věnuje studiu vlastností připravených experimentálních senzorů na NO2, zejména vlivem vlastností iontových kapalin na sledované parametry senzoru.
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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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Liquid Electrolytes for Lithium-Ion Batteries with Enhance Fire Safety
Máca, Josef ; Paidar,, Martin (referee) ; Studničková, Marie (referee) ; Sedlaříková, Marie (advisor)
Dissertation thesis is focused on study of liquid electrolytes for lithium ion batteries. The electrical and physical properties of aprotic electrolytes are observed. The main goal is to increase the fire safety of the batteries. An anhydrous solvents and there blends was investigated. The common used solvents mixtures and new low flammable solvents were used. The common used solvents were used propylene carbonate, ethylene carbonate and others. The new solvents were sulfolane and dimethyl sulfone. In the second part of the work the phosphor base flame retardants as additive in electrolytes was investigated. The last part deals with ionic liquids and there possible use as electrolyte in lithium ion batteries.
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Study of electrical and dielectric properties of ionic liquids
Mitáčková, Martina ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This bachelor thesis is focused on the study of electrical and dielectric properties of ionic liquids. Two types of OECT substrates with different semiconductor channel lengths made of PEDOT:PSS were used to measure these properties. The dielectric properties were measured by impedance spectroscopy, where the dependence of the impedance value and its phase angle on the voltage frequency was measured. It was found from V-A characteristics, that the best closing of semiconductor layer occurs at a positive UGD voltage. The switching speeds of different ionic liquids were compared for this voltage.
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Study of transistor properties with ionic liquids
Mitáčková, Martina ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This diploma thesis is focused on the study of electric and dielectric properties of transistors based on ionic liquids. The measurements were performed on organic electrochemical transistors with a semiconducting channel made of PEDOT:PSS, which were firstly prepared on ITO substrates, later they were printed using 3D print. Ionic liquid NO4 (1-butyl-3-methylimidazolium hydrogensulfate) was used for measuring of the properties. Electrical properties were determined by measuring volt-ampere characteristics, dielectric properties were measured by impedance spectroscopy.
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Study of ion liquids transistor properties
Maráčková, Lucie ; Nešpůrek, Stanislav (referee) ; Sládek, Petr (referee) ; Zmeškal, Oldřich (advisor)
The doctoral thesis is focused on ionic liquids, electrochemical transistors and the study of their electrical and dielectric properties. Current-voltage characteristics were used for determination of the electrical properties of measured ionic liquids. Impedance spectroscopy was used to determine the dielectric properties of measured ionic liquids. Transient measurement was used to determine the electrical properties of measured organic electrochemical transistors based on ionic liquids. Models of every measured ionic liquid was assembled from current-voltage characteristic and from impedance spectroscopy. Models of every measured organic electrochemical based on ionic liquids was assembled from transient measurement.
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Gel Polymer Electrolytes for Electrochemical Power Sources
Jahn, Michal ; Bartušek, Karel (referee) ; Paidar,, Martin (referee) ; Sedlaříková, Marie (advisor)
Dissertation thesis is focused on study of gel polymer electrolytes for electrochemical power sources, but also for other application. The electrical, electrochemical, mechanical and optical properties of gel electrolyte samples were measured in this work. The main goal was to prepare samples with high specific conductivity and with largest possible potential windows. Thermal stability of some samples was also monitored using thermogravimetric analyzes. The optimization of the chemical composition, quantities and ratios of individual chemicals has been made. Comparison of thermal polymerization and UV polymerization was performed. In the first part of the work, aprotic solvents and their mixtures in combination with lithium and sodium salts and one ammonium salt were investigated. Another subject of research was various crosslinking agents with methacrylate-based monomers. The second part of the work investigated the effect of ionic liquids, phosphor base flame retardants and nanoparticles as additives to gel electrolytes. In the last part of the work, the influence of the magnetic and electric field on the polymerization of gel electrolytes containing nanoparticles and selected copolymers was studied. Finally, a Li-ion cell with a graphite anode, LiFePO4 cathode and selected gel electrolyte was assembled.
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