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Distribution of sulfur isotopes in peat bogs
Haluzová, Eva ; Mihaljevič, Martin (advisor) ; Zachariáš, Jiří (referee)
The goal of this barchelor thesis is to describe the influence of human activity to sulphur cycle and monitoring processes and changes in this cycle with the assistance of specific sulphur isotopes. The first part describes sulphur and its compounds, then appearence in environment and its total cycle. The next part is focused on specific sulphur isotopes and thein application in studies of soils and peats. The final part summarizes total results and informations of human activity and it's influence on the sulphur cycle.
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Trends in composition of atmospheric precipitation and deposition in Europe
Šimková, Petra ; Hůnová, Iva (advisor) ; Maznová, Jana (referee)
This bachelor thesis describes the historical development of emissions and their associated composition of atmospheric precipitation and atmospheric deposition in Europe. It is the work with review character, which summarizes and evaluates current knowledge of the majority components of atmospheric deposition. It relies particularly on articles and a summary reports of monitoring networks devoted to the large time horizon. At the beginning part of this work are defined the major components of atmospheric deposition. In another part is described composition of atmospheric precipitation, sampling dry and wet deposition and subsequent chemical analysis. The main part is devoted to evaluate the development of emission and sputtering of the main trends of acidifying compounds, and basic cations in Europe. Emission and deposition trends are divided into time periods, which were defined in relation to the development of historical, political or economic situation. Another criterion in the evaluation of trends in the composition of atmospheric precipitation and atmospheric deposition was the State's geographical position within Europe. There are summarized the results of studies on the deposition trends across Europe, but the main attention is devoted to the differences between Western and Eastern Europe...
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Determination Of The Most Suitable Ratio Of Cathode Materials For The Lithium-Sulfur Battery System
Benešová, Petra
This paper presents the topic of lithium-sulfur batteries with a main focus on the influenceof different ratio of the cathode materials on the final electrochemical performance of the cell.The theoretical part of the article provides a comprehensive overview of the Li-S technology, mainadvantages and challenges related to the practical use of Li-S systems, and briefly mentions thetypical cathode materials. The objective of the experimental part is to provide a comparison of differentratios of cathode materials in terms of their electrochemical performance, taking into considerationthe physicochemical properties of prepared materials.
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Determination of the most suitable ratio of cathode materials for the lithium-sulfur battery system
Benešová, Petra ; Kazda, Tomáš (referee) ; Jaššo, Kamil (advisor)
This master's thesis deals with a topic of determination of the most suitable ratio of cathode materials for the lithium-sulfur systems. The first two chapters provide a general introduction to the topic of electrochemical energy sources and present the commonly used primary and secondary battery systems with emphasis on their characteristics and applications. The core of the theoretical part is dedicated to lithium-ion and lithium-sulfur batteries, their working principles along with the benefits or drawbacks related to the particular systems, and widely used materials. The experimental part briefly comments on determining the suitable electrode paste preparation method, the subsequent main part is focused on evaluation of electrochemical performance of cells using different ratios of cathode materials. Five samples of cathode materials were prepared, where the sulfur ratio is in range from 64 to 88 wt. %. Finally, the comparison of all prepared ratios in terms of their electrochemical properties is provided.
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Modification Of The Production Of Positive Electrodes For Lithium-Sulfur Batteries
Jaššo, Kamil
The rapid development of electrical wearable devices and electric cars is forcing battery industry into developing more efficient and economic energy storage systems. One of the attractive candidates among these systems are Li-S batteries. These next-generation high-energy rechargeable batteries are promising mainly thanks to their high theoretical energy density and low cost. However, the safety concerns of lithium anode, insulating properties of sulfur and rapid drop of capacity during cycling due to dissolution of polysulfides are key limitations of practical use. A cell composed of metal lithium anode and carbon doped sulfur cathode in environment of *LiTFSI:LiNO3 DME:DOL electrolyte can be considered a basic lithium-sulfur cell. This type of lithium-sulfur cell is used in many scientific publications. This paper discusses the production of positive electrodes for lithiumsulfur cells and modifications of their production.
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Influence Of Ambient Temperature On Electrochemical Parameters Of Lithium-Sulfur Batteries
Jaššo, Kamil
With the increasing popularity of electric vehicles, the demand for their range is increasing and thus demand for the batteries that power them. Range of current electric vehicles using Li-ion battery technology is around 250 miles (400 km). In the case of use of new prospective next-gen batteries such as Lithium-sulfur (Li-S) range of the electric vehicle may be doubled or even tripled. However, there are many challenges ahead of using these batteries in electric vehicles. Since the batteries in electric vehicles are largely affected by ambient temperature, this article deals with researching the effect of ambient temperature on lithium-sulfur batteries.
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Synthesis and reactivity of hypervalent sulfur fluorides
Ajenjo, Javier ; Beier, Petr (advisor) ; Jahn, Ullrich (referee) ; Cibulka, Radek (referee)
The pentafluorosulfanyl (SF5) group displays remarkable and unique properties, including large dipole moment, high electronegativity, high thermal and chemical stability, as well as high lipophilicity. However, only a few synthetic methods for the preparation of aromatic pentafluorosulfanyl building blocks have been developed to date. This work aims at improving availability and accessibility of aryl sulfurpentafluoride building blocks. In the first part of the work, the synthesis of aryl sulfurpentafluorides by the direct fluorination of diaryl disulfides with elemental fluorine is described. Nowadays, this synthetic strategy is used by industry on a multi-kilogram scale. However, the scope of the reaction is only limited to 3- and 4- nitro-1-(pentafluorosulfanyl)benzenes. In this work, the synthesis of various para-, meta- and ortho-substituted-(pentafluorosulfanyl)benzenes following the same approach was carried out. In the second part, the derivatization of aryl sulfurpentafluoride building blocks was investigated. Direct fluorination of 3-nitro-1-(pentafluorosulfanyl)benzene afforded 3-fluoro-5-nitro-1- (pentafluorosulfanyl)benzene. The titled compound was derivatized by two different processes: nucleophilic aromatic substitution (SNAr) of fluorine and vicarious nucleophilic substitution of...
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Effect of temperature on electrochemical parameters of Li-S battery
Bečan, Jan ; Skala, Kateřina (referee) ; Jaššo, Kamil (advisor)
This bachelor's thesis deals with the production of lithium-sulfur battery and the effect of changing temperatures on its electrochemical parameters. The theoretical part is focused on primary and secondary batteries and their historical evolution, anode and cathode materials for lithium-ion batteries and next-generation batteries. The practical part is focused on preparing the electrode material for lithium-sulfur battery, completion of electrochemical cell and measuring the values of cycling charge/discharge at different temperatures.
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Carboxymethyl Cellulose As The Binder For
The Lithium-Sulfur Batteries
Jaššo, Kamil
Demand for the high energy density batteries significantly increased along with the rapid development of new power source depending technologies. While these technologies are rapidly evolving, the battery industry is lagging behind unable to meet the demand. As a prospective successor to the existing li-ion battery technology, can be the high-capacity lithium-sulfur battery system (Li-S). The most commonly used composition of the positive electrode material of Li-S batteries is a mixture of sulfur, carbon and PVDF1 binder mixed in NMP2 solvent, which is (according to the WHO3) slightly toxic. The article deals with a replacing PVDF with organic non-toxic water-soluble binder.
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Advanced Technologies In Battery Sources
Pagáčová, Lenka
This article discusses the advanced technologies in battery sources. Introduction is focused on our modern society in conjunction with electrochemical energy sources. The core of article include two plots from this topic and explains the parameters of different sources. In the last part of this article is presented one type of energy source that is not currently used in practice, however it can be interesting for future aplications. Conclusion sumarizes the information from article.
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