National Repository of Grey Literature 20 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Review of In-situ and Ex-situ Techniques for Characterization of Li-ion Batteries
Klvač, Ondřej ; Kazda, Tomáš
This paper describes the analytical techniques andsample preparation methods used in in-situ and ex-situ investigationsof Li-ion batteries (LIBs). The introduction briefly describesthe current state of Li-ion batteries and their aging mechanisms.The article is further divided into a description of ex-situ and insitutechniques. Ex-situ techniques include a detailed descriptionof sample preparation for repeatable results using Broad IonBeam (BIB) polisher. In-situ techniques are described in theform of a report of selected published experiments. The paper isfurther extended with our experiments involving ex-situ analysesof cylindrical and flat cell types using BIB in planar modeand cross-section mode. In the case of in-situ experiments, thedesign of the cell inside the SEM chamber is described. Twoexperiments have been performed - on the surface of a MEMSchip, and also using a micromanipulator as a current collectorof the investigated electrode.
Analysis of electrical properties of ionic-liquid-based polymer electrolytes with respect to their crystallinity
Chválová, Zuzana Lujza ; Holcman, Vladimír (referee) ; Sedlák, Petr (advisor)
Solid polymer electrolytes based on ionic liquids are promising materials to replace conventional liquid electrolytes for electrochemical technologies. This bachelor’s thesis deals with their electrical characterization using dielectric relaxation spectroscopy. Mainly their electrical conductivity is analyzed and the results are described with respect to the different level of the crystalline structure of the electrolytes, caused by different preparation conditions. Subsequently, the work focused on the description of the charge transport mechanism, ion conductivity models, and their verification. The results showed that the crystallinity of the electrolytes decreases with the increase of evaporated solvent, which also leads to an increase in their conductivity. Jonscher type power law, which generally describes charge transport mechanisms in the studied electrolytes, and Dyre’s model, which is suitable for describing conductivity at higher frequencies, were verified.
Ion Transfer Voltammetry across the Polarized Ionic Liquid/Water Interface: Base for Electrochemical Sensors
Langmaier, Jan ; Samec, Zdeněk
Some electrochemical techniques such as voltammetry at the polarized interfaces between two\nimmiscible electrolyte solutions (ITIES) represent interesting alternatives to classical\nelectrochemistry. The benefit of the ion transfer voltammetry lies in the possibility of detection\nof ionic species which are not otherwise redox active. The methodology enables apart of direct\ndetermination of ionic samples (including pharmaceutical and clinical ones) also to monitor\nreaction processes (acido-basic, enzymatic, etc.), determination of reaction substrates and\nproducts in one experimental step, evaluation of reaction and transport kinetics, and estimation\nof lipophilicity of involved species.
Cellulose dissolution: Comparison of two non-derivatizing solvent systems and the effect of additives
Kotov, Nikolay ; Dybal, Jiří (advisor) ; Pop-Georgievski, Ognen (referee) ; Šloufová, Ivana (referee)
Title: Cellulose dissolution: Comparison of two non-derivatizing solvent systems and the effect of additives Author: Nikolay Kotov Institute: Institute of Macromolecular Chemistry, Czech Academy of Sciences Supervisor of the doctoral thesis: RNDr. Jiří Dybal, CSc. Consultant: Mgr. Adriana Šturcová, Ph.D. Institute of Macromolecular Chemistry, Czech Academy of Sciences, Department of Vibrational Spectroscopy Abstract: Cellulose is an abundant renewable material, which processing and applicability is limited owing to cellulose inability to dissolve in commonly used solvents. Only specific solvents or their combinations are able to dissolve cellulose and its dissolution processes remain unclear till nowadays. Aim of this thesis was to acquire new experimental information on the changes which cellulose exhibits upon dissolution in two exemplary solvents: an ionic liquid 1-butyl-3-methylimidazolium chloride (bmimCl) and in an organic solvent N,N-dimethylacetamide (DMAc) with lithium chloride (LiCl). The main tool for that investigation is vibrational spectroscopy which provides valuable information about the polymer structure. Similarities and differences found in the spectra of cellulose in those two solvents and influence of cellulose on the solvents are analyzed. Furthermore, influence of additives on the...
Study of Electric Properties of Electrochemical Transistors with Ionic Liquids
Blahut, Jan ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This bachelor’s thesis is focused on preparation of organic electrochemical transistors and following characterization of electric properties of these systems. Two types of electrode systems were used for preparation – glass substrates with steamed oxide of indium and tin and polylactic acid substrates with admixture of carbon soot. Three methods were tested for creation of PEDOT channel. Materiál printing, spin-coating and manual application. The measurement shows, that voltage applied to gate electrode has no effect switching of transistor. Size and polarity of current between source and drain electrodes has a major influence here.
Ionanofluids Prepared from a Series of Ionic Liquids: Preparation, Heat Capacity Measurement and Advanced Data Analysis by\nMathematical Gnostics.
Parmar, Nirmal
In the present work, isobaric heat capacity was measured as a function of temperature for the prepared ionanofluids samples.\nMoreover the influence of the size of the ion of ionic liquid on the isobaric heat capacity of ionanofluids was studied.
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Tribological characteristics of smart fluids
Michalec, Michal ; Čermák, Jan (referee) ; Svoboda, Petr (advisor)
The master's thesis deals with experimental study of tribological characteristics of smart fluids. Smart fluids are substances in liquid state reacting to the presence of magnetic or electric field by change in rheological properties. For possible application in devices using conventional lubricants is necessary to choose suitable smart fluid and study the influence of excitation on formation of lubricating layer, friction and wear. Comprehensive description of excitation influence is executed using three experimental devices and theoretical model for measurements parameters specification. Assessed are lubricant film thickness, friction coefficient and wear under smart fluid activation in non-conformal contact. Results show significant observable influence of smart fluids excitation on all assessed aspects. Understanding the mechanisms of smart fluids excitation can be a key step in development of intelligent devices with active external control of lubricant behaviour and character, that could lead to maintenance cost reduction and effectivity improvement.
Electrode Materials And Electrolytes For Aluminum-Ion Accumulators
Benešová, Petra
This article presents the topic of aluminum-ion batteries, which may become an available alternative to commercially used lithium-ion batteries. Theoretical part of the paper focuses on the basic principles of aluminum-ion accumulators, their advantages in comparison with lithium-ion batteries, and the current state of research on electrode materials and electrolytes for Al-ion batteries. The experimental part deals with preparation of carbon based cathode material, ionic liquid electrolyte and subsequent assembly of the electrode cell. Basic measurements were made to verify the electrochemical activity of the assembled cell. Eventually, the obtained results and following procedures or process modifications are discussed.
Cellulose dissolution: Comparison of two non-derivatizing solvent systems and the effect of additives
Kotov, Nikolay ; Dybal, Jiří (advisor) ; Pop-Georgievski, Ognen (referee) ; Šloufová, Ivana (referee)
Title: Cellulose dissolution: Comparison of two non-derivatizing solvent systems and the effect of additives Author: Nikolay Kotov Institute: Institute of Macromolecular Chemistry, Czech Academy of Sciences Supervisor of the doctoral thesis: RNDr. Jiří Dybal, CSc. Consultant: Mgr. Adriana Šturcová, Ph.D. Institute of Macromolecular Chemistry, Czech Academy of Sciences, Department of Vibrational Spectroscopy Abstract: Cellulose is an abundant renewable material, which processing and applicability is limited owing to cellulose inability to dissolve in commonly used solvents. Only specific solvents or their combinations are able to dissolve cellulose and its dissolution processes remain unclear till nowadays. Aim of this thesis was to acquire new experimental information on the changes which cellulose exhibits upon dissolution in two exemplary solvents: an ionic liquid 1-butyl-3-methylimidazolium chloride (bmimCl) and in an organic solvent N,N-dimethylacetamide (DMAc) with lithium chloride (LiCl). The main tool for that investigation is vibrational spectroscopy which provides valuable information about the polymer structure. Similarities and differences found in the spectra of cellulose in those two solvents and influence of cellulose on the solvents are analyzed. Furthermore, influence of additives on the...
Electrode materials and electrolytes for aluminium-ion accumulators
Benešová, Petra ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
This bachelor thesis presents a topic of aluminum-ion batteries, which have recently attracted great attention owing to their good electrochemical performance and possible use in commercially produced electronics. The paper introduces the basic principles of the function of aluminum-ion accumulators and their advantages, which are a main motivation for further research. The main feature of the theoretical part is an overview of the current state of research on suitable electrode materials and electrolytes for this type of accumulators. The experimental part is focused on the preparation of several carbon-based cathode materials, preparation of the IL-type electrolyte and subsequent cell assembly. The obtained results are evaluated and briefly discussed, taking into account the effects of the cell components and other factors.

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