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Monitoring of Electrode Changes of Negative Electrode for Lead-Acid Batteries by Operando Confocal Microscopy
Hálová, Hana ; Vanýsek, Petr (referee) ; Chladil, Ladislav (advisor)
The thesis is focused on the laser microscopy observation of the negative electrode for lead-acid batteries during their cycling. The surface changes are evaluated during both deep cycling and PSoC (Partial State of Charge) cycling. The mode leads to gradual degradation of the negative electrode – mostly because of irreversible sulfation. The speed of the sulfation can be influnced by additives of the negative active mass added already during production process. The active mass was firstly examined by electron microscope and X-ray diffractometer. The crystal growth during cycling was observed using confocal microscope Olympus Lext OLS4100.
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Electrical characteristics of graphene layers and their use as gas sensors
Kučera, Štěpán ; Kaspar, Pavel (referee) ; Macků, Robert (advisor)
This bachelor thesis focuses on the general characterization and description of graphene and related nanostructures. It involves production by the most used methods, including their advantages and disadvantages. Due to the impossibility of connection in the usual way, the graphene sample had to be contacted under visual inspection with a microscope with the tip contacts in the shielded area. Subsequently, it was subjected to current-voltage characterization with normal conditions on a Keithley 4200-CSC instrument. The next step was to measure the same sample under a different gas atmosphere. The result is a comparison of the specific responses to the change in gas atmosphere in which the graphene monolayer was exposed.
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Proposition of grounding enhancing cement composite mixture
Sochor, David ; Bydžovský, Jiří (referee) ; Drochytka, Rostislav (advisor)
The bachelor thesis deals with the design of a conductive cement composite grounding mixture for protection of building structures in areas with low conductivity. The theoretical part is mainly focused on summarizing the knowledge of the current protection of buildings against lightning and overvoltage. The study includes knowledge in the field of conductive building materials and aims to present the design of a cement composite mixture to improve grounding. Choosing the right raw materials to achieve electrical conductivity. A maintenance-free material has been developed, no humidity needed material while maintaining conductivity. The work it examines the possibilities of using industrial wastes as secondary raw materials. The conclusion focuses on laboratory testing of newly developed materials, summary and discussion of the results. With the developed samples, the resistivity was greatly reduced. The positive effect of ferric dust and carbon particles has been demonstrated.
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Diffusion of carbon in welding joints of low alloys and high alloy steels.
Zdvořáček, Marek ; Rek, Antonín (referee) ; Stránský, Karel (advisor)
Content of a document result measurements and analysis carbon´s diffusion at welding joint created from hight alloyed austenitic steel CSN 417242 and not alloyed steel CSN 412 050. Samples have been put throught isothermal anneal in a temperature range 500 °C up to 1100°C. Aim one´s effort to metalographyic quantification carburized and uncarburized zone. The next part of the document content measuring x-ray energy through microanalysis, where has been record course of a carbon disintegration and selected replacements elements at whole length of the welding joint . At the end of experimental part has been gauged course microhardness HV 0,05 at whole lenght of welding joint, from an acquired data has been chose the most optimal temperature of isothermal anneal, to produce the smallest structural notch.
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Factors influencing the Character of Phase Transformations in the Fe - C System
Gubán, Ivan ; Němec, Karel (referee) ; Molliková, Eva (advisor)
The goal of this thesis is the study of the factors influencing the character of the phase transformation in the Fe-C system. Focusing on the speed of the cooling of alloys under the consideration and concentration of carbon in the alloy, which influences the form of carbon gelling in the alloys of iron and the resulting structure of the material. Because of the limited range, the thesis does not take into account the influences caused by the presence of the impure and alloying elements. The illustrations of the microstructure of the particular alloys or their schematic illustration. In conclusion, there is included transformation diagrams of the particular steel.
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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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Carbon materials for power sources
Tichý, Jiří ; Novák, Vítězslav (referee) ; Barath, Peter (advisor)
This work deals with carbon materials and using them in alternative energy sources. Object of this work was prepared electrodes with carbon materials and investigate their electrical properties. The practical part objects of the carbon materials, their properties and application in fuel cells and Ni-Cd batteries. Analysis describes the electrochemical processes in electrode materials with carbon as conductive element.
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Binders for supercapacitors electrodes
Gottwald, Tomáš ; Dvořák, Petr (referee) ; Sedlaříková, Marie (advisor)
This work deals with the issues of useing binders for supercapacitor electrodes and optimizing the technological process for their production. The work focuses on optimizing the amount of binder used in order to acheive the most capacity. The methodology consists of creating an appropriate experimental electrode and subsequent measuring its associated capacity with AutoLab. This aproach leads to creating grafs which show the dependencies of capacity on the amount of binder used.
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Optimalisation of coposite materials for civil engineering
Kazda, Tomáš ; Chladil, Ladislav (referee) ; Novák, Vítězslav (advisor)
This work is focused on optimalisation of coposite materials for civil engineering. In the theoretical part of the project is introduction of the composite materials and materials which are used for their production. There are also concerned their properties and possible application areas. In conclusion of theoretical part this project is a summary of the possible use of composite materials. The practical part compares the characteristics of the different types of composites made in terms of conductivity and the rate of corrosion.
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Application of graphite in thermal management of microelectronics
Havlíček, Václav ; Mačák, Martin (referee) ; Vyroubal, Petr (advisor)
Tato práce je zaměřena na zlepšení tepelného managementu mikroelektroniky implementací materiálů na bázi uhlíku, přesněji grafitových fólií, do tepelné architektury mikroelektroniky. Práce začíná vysvětlením současných metod chlazení a výzev v oblasti mikroelektroniky. Poté přechází k běžně používaným materiálům - hliníku a mědi a přidává do výběru i uhlíkové alotropie. Ve druhé části tato práce obsahuje několik příkladů použití pyrolytické grafitové fólie v tepelném managementu mikroelektroniky, prokazuje jeho použitelnost a analyzuje přínosy pro šíření tepla, tepelnou vodivost při dodržení elektrické izolace a možné využití ve flexibilní elektronice.
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