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The cycle modes of lead-acid batteries
Mičák, Tomáš ; Tošer, Pavel (referee) ; Vaculík, Sebastian (advisor)
Main goal of the diploma thesis is to examine lead-acid accumulator and to study cycling modes in different setups. Theoretical part describes history, types of maintenance-free batteries, degradation mechanisms and possibilities to remove them. Practical part involves the production of electrodes and experimental cell, composition of active mass and measurement of internal resistance. Different configurations for deep cycling are researched as well. The results of the work are summarized and commented at the conclusion of the thesis.
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The influence of zinc ion on possitive elektrode of Ni-Zn accumulators
Karásek, Stanislav ; Novák, Vítězslav (referee) ; Chladil, Ladislav (advisor)
This thesis deals with the establishment of zinc ions at the positive electrode of nickel-zinc batteries. The aim of the study was to measure the impedance characteristics of the positive electrode in various states of charge and observing the effect of ZnO on the changes of impedance spectra. The theoretical part is focused on nickel hydroxide as a construction material for positive electrode and its behavior during cycling in the electrolyte. The experimental part describes in detail the manufacture of the electrode system and the preparation of electrolytes with different degrees of saturation with zinc oxide. The cells were cycled and measured using impedance spectroscopy. The measured impedance curves were simulated with equivalent circuits for a better understanding of the ongoing processes.
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Dynamic model of the batteries
Milichovský, Miloš ; Vaculík, Sebastian (referee) ; Tošer, Pavel (advisor)
The thesis includes the basic principles of lead-acid, NiCd, NiMH and Li-Ion batteries. There is a description of their features and phenomena that processes in the batteries during charging and discharging. The most important part is devoted to dynamic models of these types of batteries, the parameters that are necessary for their modeling, and testing of absolute error models. Further, the model in Matlab was created which allows the simulation of the GRID-OFF photovoltaic system using the battery model.
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Composite electrode materials for lithium-ion batteries based on LiFePO4 prepared using GAC method
Vilhelm, Ondřej ; Neoral, Jiří (referee) ; Čech, Ondřej (advisor)
Presented work investigates the problem of secondary lithium-ion cells and the different available cathode materials. We have prepared samples of LiFePO4 with the addition of different kinds of carbon materials such as Super P, Vulcan and expanded graphite. We have always created the sample with and without surfactant. Developed samples were compared by measuring electrochemical methods (cyclic voltammetry, charge and discharge cycles and impedance spectroscopy). We also modeled the three-point cell for measuring electrochemical electrode materials.
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The influence of cobalt additive on parameters of positive electrode for Ni-Cd accumulators
Svoboda, Michal ; Svoboda, Vít (referee) ; Špičák, Petr (advisor)
The Master´s thesis deals with description of the influence of cobalt additive on positive electrode parameters for Ni-Cd accumulators. Trough the use of Electrochemical Quartz Crystal Microbalance are analysed the effects which decline effective life of positive electrode during accelerated cycling. Theoretical part describes important characteristics of Ni-Cd accumulators, the working principle and effects which are in progress on positive electrode during cycling. The next part deals with description of system EQCM and the pricnciples of doping active mass with cobalt additive. Practical part consists of EQCM system calibration and electrochemical measurements. The principal aim is detection of the influence of cobalt additve on active mass during cycling in different electrolytes. From the results of measurements is set the optimal amount of cobalt additive.
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Study of electrolyte influence on diaphragm discharge stability and efficiency
Němcová, Lucie ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This thesis is focused on so-called diaphragm discharge, which is one kind of electric discharges in liquid, which belongs among so-called AOP´s techniques, still more used for water cleaning in the present. One of effectiveness and stability indicators of diaphragm discharge is generation of hydrogen peroxide. In theoretical part, detail principle description of electric discharge in liquid is situated. Further, properties of electrolyte are introduced and general spectrophotometric method of obtained sample determination is described. In experimental part, a full procedure of experiment is introduced. Next part containing results and discussions introduces particular results of individual measurements and their reasons. Final chapter is the end, which forms total summary and evaluation of all results. By the application of all chosen electrolytes in solution at diaphragm discharge formation of hydrogen peroxide has appeared. Inorganic and organic electrolytes were used. As inorganic electrolytes following salts were selected – solutions of halogenides, next sodium nitrate as a representative of nitrates, potassium dihydrogenphosphate as a representative of phosphates, etc. Representative of organic electrolytes was citric acid. The value of initial conductivity of electrolytes had the main influence on hydrogen peroxide formation. Electrolytes potassium dihydrogenphosphate and sodium sulphate the great influence on effectiveness and stability of the diaphragm discharge. Their rate constants reached maximum value by the application of solution with initial conductivity of approximately 400 mikrosiemens, particularly 0.0492 mmol/l.min and 0.048 mmol/l.min. On the contrary, low values of rate constant were achieved in electrolyte ammonium chloride at around the same initial conductivity – 0.0269 mmol/l.min. During experiments stainless steel and platinum electrodes were used. It was found that kind of electrode material hadn’t influence on generation of hydrogen peroxide. Hydrogen peroxide was formed only in the cathode space.
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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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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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