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Investigation of intercalation of alkaline metals in electrochromic devices
Kortyš, Petr ; Špičák, Petr (referee) ; Svoboda, Vít (advisor)
This work deals with investigation of intercalation of alkaline metals in electrochromic devices by the help of the quartz crystal microbalance method. The general aim is to investigate the influence of molar mass and resistance on properties of vanadium pentoxide and tungsten trioxide electrochromic films. The main measuring method used for investigating of interacalation of sodium and lithium ions into these films is the cyclic voltammetry. Drawn graphs reveals that sodium and lithium ions shows different qualities during intercalation, particularly in participation of solvent, therefore, in the influence of molar mass and in structural changes in the films.
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Study of manganeese oxides properties by the EQCM method
Pléha, David ; Špičák, Petr (referee) ; Novák, Vítězslav (advisor)
The present work deals with the use of manganese oxide as a catalyst for positive electrode of fuel cells. The theoretical part is to analyze the problem of fuel cells, focusing on lowtemperature fuel cells. Are discussed and the methods of measurement and evaluation of properties of manganese oxide layer. The practical part deals with doping electrolytic manganese dioxide salts of divalent metals and monitoring their behavior in the cyclic voltammetry by the EQCM method.
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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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Study of Metal Oxides and Hydroxides in Aqueous Solutions
Špičák, Petr ; Trnková, Libuše (referee) ; Kadlec, Jaromír (referee) ; Kazelle, Jiří (advisor)
This dissertation work deals with analysis of nickel hydroxide phases, their oxidation compounds, their stability and degradation mechanisms of electrochemically more active alpha phase on standard beta phase. The active material was prepared by both methods, electrodeposition and chemical precipitation. Main analysis method was Electrochemical Quartz Crystal Microbalance in combination with common analytical methods (cyclic voltammetry, potenciometry) can resolute between alpha and beta phases and quantitatively describe differences in main reaction by monitoring mass changes in the active material. Poor stability of the ?-Ni(OH)2 were improved by adding cations with valence two three and four into the structure instead of Ni atoms. The most important role plays cobalt and its hydroxide. Totally new way is to use titanium in combination with other cations. In electrolyte the most significant addition is LiOH, which has beneficial influent on cycle ability, stability in strong alkaline medium and cycle life.
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Investigation of mass changes by piezoelectric resonator
Kužílek, Jakub ; Svoboda, Vít (referee) ; Špičák, Petr (advisor)
An operation deals with a concept of the new cell for measuring weight changes with high precision through the use of quartz crystal micro-scales called QCM. The new cell is destined for crystal resonators which diameter is 14mm. The resonators are produced in the Czech Republic. A price is the greatest advantage of crystal resonators in comparison with original crystals. The next positive is higher mechanical tolerance which is outgoing of a guest-size. The cell designed by this way is tested in electrochemical system where a deposition of metallic copper in crystal is happening. A homologation of accuracy is judged by Faraday’s law and using Sauerbrey equation for quartz crystal microbalance in cyclic voltammetry measurement method.
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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.
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Ionexchange membranes for fuel cells
Chladil, Ladislav ; Špičák, Petr (referee) ; Barath, Peter (advisor)
Bachelor’s thesis engages in the analysis of ionexchange polymer electrolytes for low-temperature fuel cell’s H2-O2 application. Object of this work was made a several version of function ionexchange membranes with electrode material by MEA technique. The theoretical part is deal of problems of the fuel cell and their application. Experimental part describes the process of preparation of electrode materials, which were doped by platinum catalyst in variable subsidy. Electrode substances were deposited on various ionexchange membranes. This function elements were measured in experimental fuel cell Quintech and measured results was evaluated.
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Study of Metal Oxides and Hydroxides in Aqueous Solutions
Špičák, Petr ; Trnková, Libuše (referee) ; Kadlec, Jaromír (referee) ; Kazelle, Jiří (advisor)
This dissertation work deals with analysis of nickel hydroxide phases, their oxidation compounds, their stability and degradation mechanisms of electrochemically more active alpha phase on standard beta phase. The active material was prepared by both methods, electrodeposition and chemical precipitation. Main analysis method was Electrochemical Quartz Crystal Microbalance in combination with common analytical methods (cyclic voltammetry, potenciometry) can resolute between alpha and beta phases and quantitatively describe differences in main reaction by monitoring mass changes in the active material. Poor stability of the ?-Ni(OH)2 were improved by adding cations with valence two three and four into the structure instead of Ni atoms. The most important role plays cobalt and its hydroxide. Totally new way is to use titanium in combination with other cations. In electrolyte the most significant addition is LiOH, which has beneficial influent on cycle ability, stability in strong alkaline medium and cycle life.
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