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Hydrogen fuel cells
Kejval, Dan ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
The replacement of the current fuels and engines presents one of the most important tasks not only for vehicle manufacturers but also in the energy industry. Whole world is trying to limit the production of greenhouse gasses which pollute the environment and switch to sources that will not produce any harmful emissions as fast as possible. One of these are hydrogen fuel cells, which are the focus of the thesis and explains how hydrogen is produced and stored. It shows the principle on which they work, what designs currently exist and also evaluates their efficiency. According to temperature and material of the electrolyte they can be divided into various types which offer a wide range of performances and their use. Thanks to that, this device began to spread both in the Czech Republic, where the effort is to firstly expand public transportation to include busses using the hydrogen fuel cells and at foreign vehicle manufacturers where carmakers such Toyota and Hyundai already mass-produce passenger cars, trucks or buses with this source of electricity.
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Electrode Active Materials for Lithium-Ion Accumulators
Čech, Ondřej ; Oriňáková, Renáta (referee) ; Paidar,, Martin (referee) ; Sedlaříková, Marie (advisor)
This doctoral thesis deals with synthesis and characterisation of electroactive electrode materials for li-ion batteries and accumulators. The work is divided into two main parts. One deals with LiFePO4 based cathode composite electroactive material and in the second is described the synthesis and utilization of monoclinic TiO2(B) as an anode for li-ion cell. The main aim of the work is to relate the synthesis procedure and structural properties of both materials to its electrochemical preformance.
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Evaluation Of Temperature Influence on Lead-Acid Battery Properties
Langer, Martin ; Zimáková, Jana (referee) ; Bača, Petr (advisor)
This work deals with lead-acid batteries, their properties and individual types that are available on the market. The temperature dependences of the battery parameters at different ambient temperatures and at different discharging and charging modes are measured here. The theoretical part of the work deals with electrochemical cells in general, description of their main parts and principles of operation. The work analyzes the types of batteries used, their advantages and negatives. In the case of a lead-acid battery, its internal structure and the function of the electrodes and the electrolyte are taken into account. Furthermore, a description of individual possible negative phenomena that take place in lead-acid batteries and contribute to the end of their service life is included. In the practical part, 6 batteries are tested at different charging currents, which provides information about their behavior both during discharge and at the time of charging. During the experiments, testing is not only performed at room temperature, but the batteries are also exposed to high temperatures up to 75 ° C.
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Fuel cells and their use
Horák, Stanislav ; Klimeš, Lubomír (referee) ; Štětina, Josef (advisor)
This bachelor’s thesis deals with background research of fuel cells and their use. The first part of this thesis is familiar with the basic principle and fuel cell constructions, as well as the types of fuel cells, with which we meet today. Another part deals with the thermodynamic calculation of the fuel cell including the production of hydrogen. At the end of the thesis are taken into account the advantages and disadvantages of the fuel cells and examples of their use.
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Stability of cathode materials for Li-ion accumulators
Janíček, Zdeněk ; Libich, Jiří (referee) ; Sedlaříková, Marie (advisor)
This diploma thesis focuses on study of positive electrode materials for Li-Ion batteries. Our aim are intercalation materials whose are really perspective materials whose are widely used in this case. The theoretical part of my thesis focus on basic study of Li-ion batteries and their parameters. We studied charging and discharging processes. AFM and SEM were used as additional techniques for study LiCoO2 a Li0,975K0,025CoO2. We tested lifetime and stability of electrode as a perspective material for electrode for Li-ion batteries.
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The influence of iron on nickel accumulator charging
Mičák, Tomáš ; Čech, Ondřej (referee) ; Pléha, David (advisor)
This bachelor's thesis is dealing with a problematics of iron influence on charging of accumulator, more precisely on its cathode. The theory describes comparision of an accumulators at our market, important properties of Ni-Cd accumulators, their function principle, events happening during charge-discharge cycles of Ni-Cd cells and measuring method that will be used to verify of the iron influence. The practical part deals with the influence of iron on the development of oxygen during process of battery charging, on how iron affects the potential shift of oxygen gassing and how temperature affects this event.
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Low ESR meter controlled by the microcontroller
Giemza, Michal ; Adámek, Martin (referee) ; Šteffan, Pavel (advisor)
This thesis describes the design and realization of the equivalent series resistance meter of capacitors. The first part discussed the theoretical issue of the equivalent series resistance of capacitor and chooses an appropriate measuring method. The second part describes the design of functional blocks of the meter and describes the realization of the final meter by the circuit and software page. The last section describes the measurement on real capacitors and its results.
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Characterization of electrochemical properties of magnesium batteries in electrolyte modification
Honč, Jiří ; Doskočil, Leoš (referee) ; Wasserbauer, Jaromír (advisor)
This thesis deals with novel electrolytes for magnesium batteries. Prepared electrolytes were composed of affordable solvents and chemicals, which can be handled at normal laboratory conditions. Specifically, solutions of tetrahydrofurane and dimethylsulfoxide with magnesium chloride, aluminium chloride, nitrilotriacetic acid and disodium ethylenediaminetetraacetic acid, were prepared. To determine electrolyte ability of magnesium stripping and deposition, the cyclic voltammetry was used. The kinetics of electrochemical reactions in terms of polarization resistance was studied by electrochemical impedance spectroscopy. Based on scanning electron microscopy and EDS analysis, the effect of atmospheric oxygen and humidity on magnesium electrode corrosion during cycling was discussed.
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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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Fuell cells
Sedláček, Tomáš ; Elcner, Jakub (referee) ; Hejčík, Jiří (advisor)
This bachelor thesis describes the distribution of fuel cells, principle of their operation and composition of the individual cell types. It states the advantages or disadvantages of the individual cell types and summarizes their basic parameters. This thesis also refers to the current state of development of fuel cells and convenient areas of their application.
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