Vojtech Svoboda - Academia.edu (original) (raw)
Papers by Vojtech Svoboda
An in-situ, non-destructive analytical technique consisting of imaging ellipsometry, quartz cryst... more An in-situ, non-destructive analytical technique consisting of imaging ellipsometry, quartz crystal microbalance (QCM) and electrochemical characterization methods such as cyclic voltammetry (a schematic of the experimental setup is shown in ) to characterize the mechanistic development of a nano-scale polymerization process of thin methylene green formation is described herein. The successful illustration of this technique marks a unique contribution of much needed characterization methodologies for material syntheses at the nano-scale, particularly in situ. Such an approach can also provide much needed knowledge and more direct evidence about mechanistic steps involved in the process.
... CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805 Yongming Tian, EvaChi and... more ... CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805 Yongming Tian, EvaChi and Plamen Atanassov Chemical & Nuclear Engineering Department, Center for Emerging Energy Technologies, University of New Mexico, Albuquerque, NM 87131 ...
Clinical Nutrition Supplements, 2003
Renewable energy systems (RES) have to be designed specifically for both site and application. A ... more Renewable energy systems (RES) have to be designed specifically for both site and application. A comparison between different RES with the aim of evaluating the performance and the relative merits of the systems as a whole and/or their components is therefore difficult. As part of the BENCHMARKING project which is an international project carried out by 10 European research organisations,
2003 IEEE Bologna Power Tech Conference Proceedings,, 2003
This paper describes a general method on how to monitor renewable energy systems (RES) and evalua... more This paper describes a general method on how to monitor renewable energy systems (RES) and evaluate the data in such a way that the operating conditions and performance of individual components and the system as a whole can be analysed and compared. The enormous variation between RES, which is the result of user requirements and local climatic conditions, makes it
Solar Energy, 2007
Operating conditions in off-grid renewable energy systems (RES) vary significantly in different a... more Operating conditions in off-grid renewable energy systems (RES) vary significantly in different applications and locations. To describe RES and the operating conditions of their components it is useful to define categories of similar operating conditions. Categories can also be used for lifetime considerations of RES components, for making recommendations and for analysing the properties and performance of a RES and its components. Categories support system designers and an economic analysis. This paper describes the process and the results of creating RES categories of similar operating conditions for batteries. Categories are defined in such a way that batteries belonging to the same category are subjected to similar operating conditions and a similar combination of stress factors. The results provide a comprehensive overview of battery operating conditions in existing off-grid renewable energy systems. This work is part of the EU research project Benchmarking. 1
Pure and Applied Chemistry, 2000
Using three synchronized, in situ, nonintrusive, real-time characterization techniques to conduct... more Using three synchronized, in situ, nonintrusive, real-time characterization techniques to conduct transient observations, we revealed mechanistic details of a polymer film growth. A thin methylene green (MG) polymer coating (of the order of 35 nm) was used as a model system in this electrochemical microgravimetric imaging ellipsometry (EmIE) investigation. The direct correlation of changes in mass (via quartz crystal microbalance, QCM), ellipsometric angles (via imaging ellipsometry) with electrochemical conditions (in cyclic voltammetry, CV) provides discrete temporal and spatial information to help us decipher the underlying steps, from which we were able to separate adsorption, reduction, oxidation, desorption, and polymerization regimes involved in the deposition process. The evidence revealed in this study could have broad impact on the general understanding regarding how a film is deposited onto a metal surface.
Journal of Power Sources, 2005
It is necessary to be able to predict the lifetime of a battery in target applications in order t... more It is necessary to be able to predict the lifetime of a battery in target applications in order to make sound technical and commercial decisions at the system design stage. In general, accurate lifetime prediction requires more than knowledge of ageing processes and the availability of battery models. A concise procedure linking user requirements, operating regimes and operating conditions of
Journal of Power Sources, 2007
An 18650 lithium ion cell was evaluated using dynamic stress test (DST) protocol for cycle life s... more An 18650 lithium ion cell was evaluated using dynamic stress test (DST) protocol for cycle life study. Reference performance tests were applied every 60 DST cycles to quantify capacity fade and peak power capability (PPC) degradation with cycles to the end of life. A quantitative incremental capacity analysis (ICA) was applied to identify extrinsic and intrinsic contributions to capacity fading, whereas the open circuit voltage (OCV) measurements were utilized to determine the correct state of charge (SOC) in order to accurately correlate the capacity fade with SOC. The analysis also helps us identify that cell polarization resistance change in the cycles is the primary culprit that bifurcates to both extrinsic and intrinsic origins in capacity fade and PPC degradation. This analysis allows us to develop better understanding in predicting battery performance and life in the rechargeable lithium batteries.
Journal of Power Sources, 2007
This work attempts to bridge laboratory and real-life battery testing data with a comprehensive a... more This work attempts to bridge laboratory and real-life battery testing data with a comprehensive analysis to provide a coherent approach for a realistic model to simulate battery performance, including life prediction. From electric vehicle field-testing results, we explain how to handle real-life data through driving cycle analysis to establish a scheme of "building blocks" that can be validated by test results obtained in the laboratory. We also show that a simple battery model can be built upon laboratory test data and validated by real-life duty cycles, therefore deriving a more realistic understanding and prediction of battery performance.
This paper describes the results of the European Union (EU) Benchmarking Project, a 3-year, multi... more This paper describes the results of the European Union (EU) Benchmarking Project, a 3-year, multi-agency research project to improve the design of renewable-based hybrid power systems based on the analysis of existing systems and the benchmarking of specific system components, most critically batteries. Based on the analysis of hundreds of power systems, efforts were made to classify different categories of similar use and then determine component-specific recommendations that will allow more consistent and longer product life. Based on the classification of different use types, assessments of critical ware factors could be conducted and recommendations of appropriate component selection undertaken. The project results make it possible to match most systems to a use category, thus allowing recommendations to improve project life.
Journal of The Electrochemical Society, 2007
ABSTRACT
Electrochemical and Solid-State Letters, 2006
... The cycle-life test was conducted with an Arbin BT-2043 battery test station, while the subse... more ... The cycle-life test was conducted with an Arbin BT-2043 battery test station, while the subsequent capacity tests with progressively higher end-of-charge voltages were performed on a Solartron 1470 station. Results. ... XQYang, X.Sun, and J.McBreen, Electrochem. ...
Electroanalysis, 2008
This paper investigates the utility of cross -lab comparative analysis of electrocatalytic electr... more This paper investigates the utility of cross -lab comparative analysis of electrocatalytic electrode performance using standardized modular stack cells and test protocols. Using poly(methylene green)-modified glassy carbon electrodes as the model system, we characterized electrode fabrication and performance with respect to the catalytic oxidation of NADH at neutral pH and low overpotential. Three sets of experiments were duplicated across four independent laboratories and the experimental results from each set were analyzed and compared in terms of key electroanalytical parameters. Statistical analyses were performed at three distinct levels: 1) the standard deviation among repetitive cycles within an experiment; 2) the standard deviation among repetitive experiments in the same laboratory, and 3) the standard deviation among experiments performed across all four laboratories. Using predefined criteria of reproducibility for each level, most parameters were found to be statistically reproducible at most levels. When a particular parameter was found to be irreproducible in a given level, commentary is given on how that information can be used diagnose what chemical/physical aspects of the process were uncontrolled or poorly understood and therefore candidates for future research. This exercise, which is presented as a proof -of-principle step towards the concept of standardizing electrocatalytic evaluation, illustrates the importance of executing electrochemical characterization protocols across several labs and using fixed geometry and dimensions, system configuration, and applied electrochemical conditions. Future work is under way to extend these principles to systems with fluid flow.
Journal of Power Sources, 2007
Determining state-of-charge (SoC) in a battery has been an important subject for the industry for... more Determining state-of-charge (SoC) in a battery has been an important subject for the industry for decades. Despite significant efforts in the past focusing on methodologies to accurately estimate SoC in a battery, the fundamental understanding of the SoC issue has not been clear, at least in the industry where testing, control, and operation are concerned. Recently, we have been working on developing reliable techniques to identify capacity loss mechanism in rechargeable lithium batteries and to quantify contributions to capacity loss from different origins. That prompted us to re-visit the SoC issue. Strictly speaking, SoC is a static thermodynamic property of battery chemistry, which should be determined at equilibrium. On the other hand, cell capacity is a quantity of practical interest often determined by kinetics; thus, it is rate dependent. We conducted a few experiments to illustrate the accurate estimate of SoC through proper measurements. We also explained the proper correlation between SoC and rate capacity. A better understanding of the charge and discharge behavior in a battery under different rates in relation to the SoC is therefore derived.
An in-situ, non-destructive analytical technique consisting of imaging ellipsometry, quartz cryst... more An in-situ, non-destructive analytical technique consisting of imaging ellipsometry, quartz crystal microbalance (QCM) and electrochemical characterization methods such as cyclic voltammetry (a schematic of the experimental setup is shown in ) to characterize the mechanistic development of a nano-scale polymerization process of thin methylene green formation is described herein. The successful illustration of this technique marks a unique contribution of much needed characterization methodologies for material syntheses at the nano-scale, particularly in situ. Such an approach can also provide much needed knowledge and more direct evidence about mechanistic steps involved in the process.
... CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805 Yongming Tian, EvaChi and... more ... CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805 Yongming Tian, EvaChi and Plamen Atanassov Chemical & Nuclear Engineering Department, Center for Emerging Energy Technologies, University of New Mexico, Albuquerque, NM 87131 ...
Clinical Nutrition Supplements, 2003
Renewable energy systems (RES) have to be designed specifically for both site and application. A ... more Renewable energy systems (RES) have to be designed specifically for both site and application. A comparison between different RES with the aim of evaluating the performance and the relative merits of the systems as a whole and/or their components is therefore difficult. As part of the BENCHMARKING project which is an international project carried out by 10 European research organisations,
2003 IEEE Bologna Power Tech Conference Proceedings,, 2003
This paper describes a general method on how to monitor renewable energy systems (RES) and evalua... more This paper describes a general method on how to monitor renewable energy systems (RES) and evaluate the data in such a way that the operating conditions and performance of individual components and the system as a whole can be analysed and compared. The enormous variation between RES, which is the result of user requirements and local climatic conditions, makes it
Solar Energy, 2007
Operating conditions in off-grid renewable energy systems (RES) vary significantly in different a... more Operating conditions in off-grid renewable energy systems (RES) vary significantly in different applications and locations. To describe RES and the operating conditions of their components it is useful to define categories of similar operating conditions. Categories can also be used for lifetime considerations of RES components, for making recommendations and for analysing the properties and performance of a RES and its components. Categories support system designers and an economic analysis. This paper describes the process and the results of creating RES categories of similar operating conditions for batteries. Categories are defined in such a way that batteries belonging to the same category are subjected to similar operating conditions and a similar combination of stress factors. The results provide a comprehensive overview of battery operating conditions in existing off-grid renewable energy systems. This work is part of the EU research project Benchmarking. 1
Pure and Applied Chemistry, 2000
Using three synchronized, in situ, nonintrusive, real-time characterization techniques to conduct... more Using three synchronized, in situ, nonintrusive, real-time characterization techniques to conduct transient observations, we revealed mechanistic details of a polymer film growth. A thin methylene green (MG) polymer coating (of the order of 35 nm) was used as a model system in this electrochemical microgravimetric imaging ellipsometry (EmIE) investigation. The direct correlation of changes in mass (via quartz crystal microbalance, QCM), ellipsometric angles (via imaging ellipsometry) with electrochemical conditions (in cyclic voltammetry, CV) provides discrete temporal and spatial information to help us decipher the underlying steps, from which we were able to separate adsorption, reduction, oxidation, desorption, and polymerization regimes involved in the deposition process. The evidence revealed in this study could have broad impact on the general understanding regarding how a film is deposited onto a metal surface.
Journal of Power Sources, 2005
It is necessary to be able to predict the lifetime of a battery in target applications in order t... more It is necessary to be able to predict the lifetime of a battery in target applications in order to make sound technical and commercial decisions at the system design stage. In general, accurate lifetime prediction requires more than knowledge of ageing processes and the availability of battery models. A concise procedure linking user requirements, operating regimes and operating conditions of
Journal of Power Sources, 2007
An 18650 lithium ion cell was evaluated using dynamic stress test (DST) protocol for cycle life s... more An 18650 lithium ion cell was evaluated using dynamic stress test (DST) protocol for cycle life study. Reference performance tests were applied every 60 DST cycles to quantify capacity fade and peak power capability (PPC) degradation with cycles to the end of life. A quantitative incremental capacity analysis (ICA) was applied to identify extrinsic and intrinsic contributions to capacity fading, whereas the open circuit voltage (OCV) measurements were utilized to determine the correct state of charge (SOC) in order to accurately correlate the capacity fade with SOC. The analysis also helps us identify that cell polarization resistance change in the cycles is the primary culprit that bifurcates to both extrinsic and intrinsic origins in capacity fade and PPC degradation. This analysis allows us to develop better understanding in predicting battery performance and life in the rechargeable lithium batteries.
Journal of Power Sources, 2007
This work attempts to bridge laboratory and real-life battery testing data with a comprehensive a... more This work attempts to bridge laboratory and real-life battery testing data with a comprehensive analysis to provide a coherent approach for a realistic model to simulate battery performance, including life prediction. From electric vehicle field-testing results, we explain how to handle real-life data through driving cycle analysis to establish a scheme of "building blocks" that can be validated by test results obtained in the laboratory. We also show that a simple battery model can be built upon laboratory test data and validated by real-life duty cycles, therefore deriving a more realistic understanding and prediction of battery performance.
This paper describes the results of the European Union (EU) Benchmarking Project, a 3-year, multi... more This paper describes the results of the European Union (EU) Benchmarking Project, a 3-year, multi-agency research project to improve the design of renewable-based hybrid power systems based on the analysis of existing systems and the benchmarking of specific system components, most critically batteries. Based on the analysis of hundreds of power systems, efforts were made to classify different categories of similar use and then determine component-specific recommendations that will allow more consistent and longer product life. Based on the classification of different use types, assessments of critical ware factors could be conducted and recommendations of appropriate component selection undertaken. The project results make it possible to match most systems to a use category, thus allowing recommendations to improve project life.
Journal of The Electrochemical Society, 2007
ABSTRACT
Electrochemical and Solid-State Letters, 2006
... The cycle-life test was conducted with an Arbin BT-2043 battery test station, while the subse... more ... The cycle-life test was conducted with an Arbin BT-2043 battery test station, while the subsequent capacity tests with progressively higher end-of-charge voltages were performed on a Solartron 1470 station. Results. ... XQYang, X.Sun, and J.McBreen, Electrochem. ...
Electroanalysis, 2008
This paper investigates the utility of cross -lab comparative analysis of electrocatalytic electr... more This paper investigates the utility of cross -lab comparative analysis of electrocatalytic electrode performance using standardized modular stack cells and test protocols. Using poly(methylene green)-modified glassy carbon electrodes as the model system, we characterized electrode fabrication and performance with respect to the catalytic oxidation of NADH at neutral pH and low overpotential. Three sets of experiments were duplicated across four independent laboratories and the experimental results from each set were analyzed and compared in terms of key electroanalytical parameters. Statistical analyses were performed at three distinct levels: 1) the standard deviation among repetitive cycles within an experiment; 2) the standard deviation among repetitive experiments in the same laboratory, and 3) the standard deviation among experiments performed across all four laboratories. Using predefined criteria of reproducibility for each level, most parameters were found to be statistically reproducible at most levels. When a particular parameter was found to be irreproducible in a given level, commentary is given on how that information can be used diagnose what chemical/physical aspects of the process were uncontrolled or poorly understood and therefore candidates for future research. This exercise, which is presented as a proof -of-principle step towards the concept of standardizing electrocatalytic evaluation, illustrates the importance of executing electrochemical characterization protocols across several labs and using fixed geometry and dimensions, system configuration, and applied electrochemical conditions. Future work is under way to extend these principles to systems with fluid flow.
Journal of Power Sources, 2007
Determining state-of-charge (SoC) in a battery has been an important subject for the industry for... more Determining state-of-charge (SoC) in a battery has been an important subject for the industry for decades. Despite significant efforts in the past focusing on methodologies to accurately estimate SoC in a battery, the fundamental understanding of the SoC issue has not been clear, at least in the industry where testing, control, and operation are concerned. Recently, we have been working on developing reliable techniques to identify capacity loss mechanism in rechargeable lithium batteries and to quantify contributions to capacity loss from different origins. That prompted us to re-visit the SoC issue. Strictly speaking, SoC is a static thermodynamic property of battery chemistry, which should be determined at equilibrium. On the other hand, cell capacity is a quantity of practical interest often determined by kinetics; thus, it is rate dependent. We conducted a few experiments to illustrate the accurate estimate of SoC through proper measurements. We also explained the proper correlation between SoC and rate capacity. A better understanding of the charge and discharge behavior in a battery under different rates in relation to the SoC is therefore derived.