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Flame retarders of polymeric materials
Winkler, David ; Poláček, Petr (referee) ; Kučera, František (advisor)
Bachelor thesis focuses on the study of expanded graphite as flame retardant added to low density polyethylene and it´s potential synergistic effect with ammonium polyphosphate. Additive and non-additive dog-bone samples were prepared by compounding and injection. Crystalization, melting point and thermal decomposition of the samples were monitored by TGA and DSC thermal analysis methods. The effect of expanded graphite on the mechanical proporties of the materiál was monitored by a tenssile test. The effect of expanded graphite as a flame retardant and its synergistic effect with ammonium polyphosphate was confirmed by a flame test in the horizontal position of the sample.
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Expanded and Flake Natural Graphite as Negative Electrode Material in Lithium-ion Cell
Paulovics, Petr ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
This diploma thesis deals with an issue of lithium-ion batteries, primarily with negative (anode) electrode materials. Natural graphite in two forms, namely flake and expanded graphite, is used in the thesis as active electrode material. It is concerned with study of their capacity and output characteristics depending on the pressing pressure and discharging current. The first part of thesis consists of theory and describes basic principles and the composition of lithium-ion batteries. Materials, their characteristics used in production and theoretical description of measurement techniques are presented then. The second part of the thesis is focused on production, assembling and measurement of the characteristics of the produced electrodes. The aim of the thesis is finding the effects of changes of pressing pressure on the capacity, stability during cycling and stability at higher loads.
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Zinc based negative electrode for alkaline accumulators
Prchal, Jiří ; Svoboda, Vít (referee) ; Špičák, Petr (advisor)
The object of this project is research and preparation of the permanent zinc electrode in a strong alkaline surrounding for the usage in Ni-Zn accumulators. This system is characterized by a low overall ecological impact on environment, higher specific energy and higher electromotive force than nowadays commonly used systems (lead, nickel-cadmium). The goal of this project is to originate a new procedure, which will make possible to steady a zinc electrode. Every research faces a problem shaping changes of zinc electrode during cycling and related low cycle life. This work consists of the theoretical part, in which is explained a basic accumulators mechanism and practical part, in which is described performed research.
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Porosity increasing agents for supercapacitors
Hovorka, Martin ; Dvořák, Petr (referee) ; Sedlaříková, Marie (advisor)
This work deals with questions connected with ultracapactors and lightening agents of activated carbon used for production of supercapacitors’s electrodes. Our goal was examination of ideal ratio of carbon and lightening agent in surveyed electrode. Materials which were used: expanded graphite, soda saleratus, ammonium bicarbonate and ammonium formate. Specimens were measured by cyclic voltammetry. The best results was reached by using of soda saleratus with ideal ratio 1:0,5. During measurement was found that weight of electrode has basic effect on eventual capacity.
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Development of negative electrodes for lithium-ions batteries
Drahokoupil, Petr ; Libich, Jiří (referee) ; Sedlaříková, Marie (advisor)
This thesis deals with lithiation of negative electrode li-ion batteries. In this thesis is used several electrode materials: carbon, FeCl3, lithiated carbon electrodes and silicon carbide. Reduction of irreversible capacity lithium-ion batteries leads to increased capacity and also we can use new materials as a positive electrode. Thesis deals with the differences in the properties of materials using lithiation and their use in practice
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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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