|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
Hydrogen production
Kunický, Ondřej ; Šnajdárek, Ladislav (referee) ; Poláčik, Ján (advisor)
Bachelor thesis deals with the production of hydrogen by electrolysis. The introductory part describes the basic properties of hydrogen, the possibilities of its storage and transport, hydrogen safety, the hydrogen economics, and the impact on the environment. Greater attention is then paid to the current possibilities of using hydrogen and its production from fossil and renewable sources. The next part of this thesis deals with possibilities of increasing the efficiency of electrolysis and the control of its performance. At the end, there is a practical measurement of electrolyser and a calculation of the efficiency of hydrogen production by electrolysis.
|
|
|
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.
|
|
|
Electrolytes for sodium - ion batteries using ionic liquids
Suský, Stanislav ; Zatloukal, Miroslav (referee) ; Máca, Josef (advisor)
The content of this work deals with a theoretical search of sodium-based batteries. The first part of the work contains an introduction to the issue of batteries, contains basic concepts, principles of secondary batteries. In the second part, the basic three divisions of sodium batteries according to the design principles are discussed in more detail. He also deals with the theory of ionic liquids. Their mechanical, thermal and electrical properties and the method used to measure electrolytes are described here. The practical part describes the measurement procedure, displays the recorded measured values and their evaluation.
|
|
|
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.
|
|
|
Temperature changes in lead-acid batteries
Grepl, Jan ; Chladil, Ladislav (referee) ; Bača, Petr (advisor)
The aim of this thesis is familiarization with the basic lead-acid batteries construction with specialization on their differences. This work is divided in theoretical part and practical part. At first, the theoretical part deals with basics of functions of electrochemical cells and their fundamental division. In the case of lead-acid batteries the work focuses on the fundamental chemical reactions and fundamental principle of their construction. Aftwerwars are also in this part included negative phenomena, which can occur during the operation of the lead-acid batteries and possibly decrease their capacity or shorten their lifetime period. In practical part takes part description of measuring station. Subsequently is realised the correction of masurement sensors. Finally there takes place an analysis of measured parameters in experimental cell in CC and CC/CV charging mode.
|
|
|
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.
|
|
|
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.
|
guest ::
