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Effect of compaction pressure to the electrochemical properties of the electrodes for Li-S accumulators
Jaššo, Kamil ; Tichý, Jiří (referee) ; Kazda, Tomáš (advisor)
The purpose of this diploma thesis is to describe the impact of compaction pressure on the electrochemical parameters of lithium-sulfur batteries. Theoretical part of this thesis contains briefly described terminology and general issues of batteries and their division. Every kind of battery is provided with a closer description of a specific battery type. A separate chapter is dedicated to lithium cells, mainly lithium-ion batteries. Considering various composition of lithium-ion batteries, this chapter deeply analyzes mostly used active materials of electrodes, used electrolytes and separators. Considering that the electrochemical principle of Li-S and Li-O batteries is different to Li-ion batteries, these accumulators of new generation are included in individual subhead. In the experimental part of this thesis are described methods used to measure electrochemical parameters of Li-S batteries. Next chapter contains description of preparing individual electrodes and their composition. Rest of the experimental part of my thesis is dedicated to the description of individual experiments and achieved results.
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Inverse vulcanised sulphur as an electroactive material for lithium-sulphur and sodium-sulphur batteries
Trochta, David ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
This thesis deals with the study of lithium-sulfur and sodium-sulfur batteries, which are designed for use at room temperatures. Both of these systems are interesting mainly due to their high theoretical capacity and low environmental impact, thus greatly outperforming lithium-ion batteries. The weakness of these new technologies is their low lifespan and the associated rapid loss of battery capacity. To increase the lifespan, elemental sulfur in this work was replaced by sulfur with an amorphous structure, synthesized by an inverse vulcanization process that has been optimized in various ways. In addition to the optimization of the inverse vulcanization technology window, the effect of the addition of carbonaceous additives during the synthesis was also investigated. In this work, a series of samples of inverse vulcanized sulfur with different ratios of input precursors were prepared and also with different additives. X-ray diffraction was used to confirm the amorphous structure of the material, which also excludes the presence of crystalline sulphur. The results of Raman spectroscopy were also presented, demonstrating the possibility of using this method to determine semi-quantitative ratios of the input precursors. Electrodes for electrochemical cells were fabricated from selected samples. The homogeneity of the distribution of the electroactive material on the electrode was investigated using a scanning electron microscope and elemental mapping by energy dispersive spectroscopy technique. The electrochemical characterization of the inversely vulcanized sulfur electrodes was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic potential limited cycling.
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Effect of Compaction Pressure to the Electrochemical Properties of the Electrodes for Li-S Accumulators
Jaššo, Kamil
Over the last decade, demand for batteries increased a lot thanks to the wearable devices and electric cars. The current trend in all industries is reducing the size and weight of batteries and increasing their capacity. The demand for even more powerful batteries is often faced with theoretical and practical limits of the technology. Battery industry compared to other industries is just slightly behind and batteries became a limiting factor for technologies.The purpose of this experiment is to describe the impact of compaction pressure on the electrochemical properties of the positive electrode for lithium-sulfur batteries.
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Effect of compaction pressure to the electrochemical properties of the electrodes for Li-S accumulators
Jaššo, Kamil ; Tichý, Jiří (referee) ; Kazda, Tomáš (advisor)
The purpose of this diploma thesis is to describe the impact of compaction pressure on the electrochemical parameters of lithium-sulfur batteries. Theoretical part of this thesis contains briefly described terminology and general issues of batteries and their division. Every kind of battery is provided with a closer description of a specific battery type. A separate chapter is dedicated to lithium cells, mainly lithium-ion batteries. Considering various composition of lithium-ion batteries, this chapter deeply analyzes mostly used active materials of electrodes, used electrolytes and separators. Considering that the electrochemical principle of Li-S and Li-O batteries is different to Li-ion batteries, these accumulators of new generation are included in individual subhead. In the experimental part of this thesis are described methods used to measure electrochemical parameters of Li-S batteries. Next chapter contains description of preparing individual electrodes and their composition. Rest of the experimental part of my thesis is dedicated to the description of individual experiments and achieved results.
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