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Electrolytes based on sulfolan and similar solvents
Máca, Josef ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
Submitted thesis deal with study of aprotic electrolytes in order to increase the safety for use in lithno – ionts accumulators. Increase of safety is specified by measuring the flash point of each electrolytes, at the same time are evaluated also other parameters important for use in accumulators. For determine the window of temperatures where the electrolytes can work is measured by melting point. The melting point is measured by cryoscopy. From electrical properties is measured specific conductivity of the electrolyte.
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Magnetic field measurement
Dušek, Jiří ; Máca, Josef (referee) ; Vyroubal, Petr (advisor)
Bachelor thesis describes ways and technology for measuring of the magnetic field. Furthermore it deals with comparing sensors for magnetic fields measuring and creating a basic conception of the meter. For design of conception was selected sensor HMC2003 from Honeywell company. Design of conception describes two units, which meter contains. Conception include power, compensation and reset circuits. After that is detailed describe layout of both printed circuit boards, setting up and soldering components. Output of this meter is signal of the three axis of sensor. Meter was subjected to trial run, which verified functionality of the whole device.
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Study of intercalation properties of electrode materials based on naturla graphite
Bílek, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This diploma thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulators made of natural graphite. The first part of this thesis points to the issue of electrochemical cells. In the theoretical part the thesis deals with the SEI layer, advantages, disadvantages, characteristics, operating principle and the use of lithium-ion accumulators. The practical part focuses on the electrochemical properties of negative electrode, especially the determination of the diffusion coefficient. Thesis also deals with electrochemical impedance spectroscopy (EIS) and its use in determining the equivalent replacement circuit and calculating the diffusion coefficient.
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Diagnostic of semiconductor materials by EBIC method
Davidová, Lenka ; Máca, Josef (referee) ; Čudek, Pavel (advisor)
Master´s thesis is focused on diagnostics of semiconductor materials by EBIC method (measuring of currents induced beam), determination of the lifetime of minority carriers, or their diffusion length. The theoretical part is aimed at the principle of scanning electron microscopy, the characteristic properties of the microscope and the signals generated by the interaction of the primary electron beam with the sample. The thesis describes a structure of semiconducting silicon, band models, types of lattice defects and doped of semiconductor structures. After that it is described the theory of calculation of the diffusion length of minority carriers in semiconductors of type N and P. The aim of the experiment part of the thesis is to measure the properties of the semiconductor structure by EBIC and determination of diffusion length and lifetime of minority charge carriers based on the measured data The aim of the experiment part of the thesis is to measure the properties of the semiconductor structure by EBIC and determination of diffusion length and lifetime of minority charge carriers on the basis of the measured data.
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Comparison of different types of commercial lithium-ion batteries and their properties under low temperature
Bičák, Tomáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of lithium-ion batteries. Describes development, technologies and materials used. The diploma thesis describes the operating principle, characteristics, advantages and disadvantages. The work is focused on the characteristic properties of commercial lithium-ion batteries under standard conditions and at reduced temperatures. At reduced temperatures, changes in properties due to low temperatures are observed. Furthermore, in this work they compare the measured values with the values given by the manufacturers.
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The Study of ZnO Crystal Growth in Supersaturated Alkaline Solution
Bannert, Tomáš ; Máca, Josef (referee) ; Chladil, Ladislav (advisor)
This thesis deals with the study of growth of zinc oxide crystals from supersaturated solutions using a scanning electron microscope and XRD methods. The work is divided into a theoretical and an experimental part. The theoretical part analyses issues related to the principle of operation of electrochemical cells with an emphasis on Ni-Zn batteries and phenomena limiting the life and efficiency of Ni-Zn batteries with a focus on phenomena that affect precipitation processes of zinc oxide crystals. It also analyses and compares the appropriateness of the methods that have been used to study the growth of the prepared zinc oxide crystals. The experimental part describes the preparation of a supersaturated solution, the process of each analysis and its evaluation. The results of each method are compared with the theoretical assumptions and among themselves. The experimental part also contains a chapter dealing with the design of in situ X-ray diffraction analysis methods of the obtained zinc oxide crystals.
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The effect of temperature on the charging and discharging characteristics of lithium-ion batteries
Doleželová, Eva ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This thesis deals with operation principles of lithium-ion batteries, its degradation principles, capacity fade, materials used, formats, main characteristics, development, uses and mid to high temperature behaviour. The thesis aims to study aging characteristics of commercially available lithium-ion batteries. In the practical part of the thesis, the key parameters of selected types of commercially available lithium-ion batteries were measured under normal temperature conditions. The measurement was repeated at an elevated temperature. Results were analysed and effects of different temperatures on the selected characteristics were concluded both verbally and graphically. A conclusion evaluates short-term and long-term impacts of ambient temperature on rate capability, ageing, capacity fade and longevity.
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Observation of lead electrode surface by atomic force microscope AFM
Bouška, Marek ; Máca, Josef (referee) ; Bača, Petr (advisor)
This master's thesis is focused on in situ observation of the negative electrode of the lead acid accumulator using atomic force microscopy AFM. Discussed topics are lead acid accumulator, atomic force microscopy, cyclic voltammetry and current knowledge of the in situ observation of the lead acid accumulator using AFM. The main task of this project is assembling the experimental cells, make in situ observation of the negative electrode surface of the lead acid accumulator. In the end evaluate if this method is suitable for the lead acid battery observation.
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