Download or read book In Situ Modeling of Chemical Membrane Degradation in Polymer Electrolyte Fuel Cells written by Ka Hung Wong and published by . This book was released on 2015 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical membrane degradation is a major limiting factor for polymer electrolyte fuel cell (PEFC) durability and lifetime. While the effects of chemical membrane degradation are characterized in the literature, the underlying mechanism is not fully understood. This motivates the development of a comprehensive in situ chemical membrane degradation model addressed in this work to determine the linkages between the membrane electrolyte assembly (MEA) macroscopic phenomena, in situ operating conditions, and the temporal membrane degradation process. Chemical membrane degradation through OH radical attack on the membrane, where the radical is produced by decomposition of hydrogen peroxide in the presence of contaminants such as Fe2+, is comprehensively investigated. A redox cycle of iron ions is discovered within the MEA which sustains the Fe2+ concentration in the membrane and results in the most severe chemical degradation at open circuit voltage (OCV). The cycle is suppressed at lower cell voltages leading an exponential decrease in Fe2+ concentration in the membrane and associated membrane degradation rate, which suggests that intermediate cell voltage operation would efficiently mitigate chemical membrane degradation and extend the fuel cell lifetime. Effectiveness of membrane additives (e.g., ceria) in mitigating the membrane degradation is explored. At high cell voltages, abundant Ce3+ ions are available in the membrane to quench hydroxyl radicals which is the primary mitigation mechanism observed at OCV conditions. However, the mitigation is suppressed at low cell voltages, where electromigration drives Ce3+ ions into the cathode catalyst layer (CL). Without an adequate amount of Ce3+ in the membrane, the hydroxyl radical scavenging is significantly reduced. Moreover, the modeling results reveal that proton starvation may occur in the cathode CL due to local Ce3+ accumulation and associated reductions in proton conductivity and oxygen reduction kinetics. Significant performance tradeoffs in the form of combined ohmic and kinetic voltage losses are therefore evident. A lower initial Ce3+ concentration is demonstrated to mitigate voltage losses without compromising membrane durability at high cell voltages. However, the harmful Fe2+ concentration in the membrane increases with the Ce3+ concentration, which suggests that ceria-supported MEAs can experience higher rates of degradation than baseline MEAs at low cell voltages. Strategic MEA design is recommended in order to ensure membrane durability at low cell voltages.
Download or read book Polymer Electrolyte Fuel Cell Degradation written by Matthew M. Mench and published by Academic Press. This book was released on 2012 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: For full market implementation of PEM fuel cells to become a reality, two main limiting technical issues must be overcome- cost and durability. This cutting-edge volume directly addresses the state-of-the-art advances in durability within every fuel cell stack component. [...] chapters on durability in the individual fuel cell components -- membranes, electrodes, diffusion media, and bipolar plates -- highlight specific degradation modes and mitigation strategies. The book also includes chapters which synthesize the component-related failure modes to examine experimental diagnostics, computational modeling, and laboratory protocol"--Back cover.
Download or read book Modeling and Diagnostics of Polymer Electrolyte Fuel Cells written by Ugur Pasaogullari and published by Springer Science & Business Media. This book was released on 2010-07-23 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, presented by leading experts in the field, covers the latest advances in diagnostics and modeling of polymer electrolyte fuel cells, from understanding catalyst layer durability to start-up under freezing conditions.
Download or read book Polymer Electrolyte Fuel Cell Durability written by Felix N. Büchi and published by Springer Science & Business Media. This book was released on 2009-02-08 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a significant number of R&D projects, performed mostly after 2000, devoted to the understanding and prevention of performance degradation processes in polymer electrolyte fuel cells (PEFCs). The extent and severity of performance degradation processes in PEFCs were recognized rather gradually. Indeed, the recognition overlapped with a significant number of industrial dem- strations of fuel cell powered vehicles, which would suggest a degree of technology maturity beyond the resaolution of fundamental failure mechanisms. An intriguing question, therefore, is why has there been this apparent delay in addressing fun- mental performance stability requirements. The apparent answer is that testing of the power system under fully realistic operation conditions was one prerequisite for revealing the nature and extent of some key modes of PEFC stack failure. Such modes of failure were not exposed to a similar degree, or not at all, in earlier tests of PEFC stacks which were not performed under fully relevant conditions, parti- larly such tests which did not include multiple on–off and/or high power–low power cycles typical for transportation and mobile power applications of PEFCs. Long-term testing of PEFCs reported in the early 1990s by both Los Alamos National Laboratory and Ballard Power was performed under conditions of c- stant cell voltage, typically near the maximum power point of the PEFC.
Download or read book Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology written by Christoph Hartnig and published by Elsevier. This book was released on 2012-02-20 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) technology are promising forms of low-temperature electrochemical power conversion technologies that operate on hydrogen and methanol respectively. Featuring high electrical efficiency and low operational emissions, they have attracted intense worldwide commercialization research and development efforts. These R&D efforts include a major drive towards improving materials performance, fuel cell operation and durability. In situ characterization is essential to improving performance and extending operational lifetime through providing information necessary to understand how fuel cell materials perform under operational loads. Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology, Volume 2 details in situ characterization, including experimental and innovative techniques, used to understand fuel cell operational issues and materials performance. Part I reviews enhanced techniques for characterization of catalyst activities and processes, such as X-ray absorption and scattering, advanced microscopy and electrochemical mass spectrometry. Part II reviews characterization techniques for water and fuel management, including neutron radiography and tomography, magnetic resonance imaging and Raman spectroscopy. Finally, Part III focuses on locally resolved characterization methods, from transient techniques and electrochemical microscopy, to laser-optical methods and synchrotron radiography. With its international team of expert contributors, Polymer electrolyte membrane and direct methanol fuel cell technology will be an invaluable reference for low temperature fuel cell designers and manufacturers, as well as materials science and electrochemistry researchers and academics. Polymer electrolyte membrane and direct methanol fuel cell technology is an invaluable reference for low temperature fuel cell designers and manufacturers, as well as materials science and electrochemistry researchers and academics. Details in situ characterisation of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), including the experimental and innovative techniques used to understand fuel cell operational issues and materials performance Examines enhanced techniques for characterisation of catalyst activities and processes, such as X-ray absorption and scattering, advanced microscopy and electrochemical mass spectrometry Reviews characterisation techniques for water and fuel management, including neutron radiography and tomography, and comprehensively covers locally resolved characterisation methods, from transient techniques to laser-optical methods
Download or read book High Temperature Polymer Electrolyte Membrane Fuel Cells written by Qingfeng Li and published by Springer. This book was released on 2015-10-15 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive review of high-temperature polymer electrolyte membrane fuel cells (PEMFCs). PEMFCs are the preferred fuel cells for a variety of applications such as automobiles, cogeneration of heat and power units, emergency power and portable electronics. The first 5 chapters of the book describe rationalization and illustration of approaches to high temperature PEM systems. Chapters 6 - 13 are devoted to fabrication, optimization and characterization of phosphoric acid-doped polybenzimidazole membranes, the very first electrolyte system that has demonstrated the concept of and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications.
Download or read book PEM Fuel Cells written by Frano Barbir and published by Academic Press. This book was released on 2012-09-25 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: Demand for fuel cell technology is growing rapidly. Fuel cells are being commercialized to provide power to buildings like hospitals and schools, to replace batteries in portable electronic devices, and as replacements for internal combustion engines in vehicles. PEM (Proton Exchange Membrane) fuel cells are lighter, smaller, and more efficient than other types of fuel cell. As a result, over 80% of fuel cells being produced today are PEM cells. This new edition of Dr. Barbir's groundbreaking book still lays the groundwork for engineers, technicians and students better than any other resource, covering fundamentals of design, electrochemistry, heat and mass transport, as well as providing the context of system design and applications. Yet it now also provides invaluable information on the latest advances in modeling, diagnostics, materials, and components, along with an updated chapter on the evolving applications areas wherein PEM cells are being deployed. Comprehensive guide covers all aspects of PEM fuel cells, from theory and fundamentals to practical applications Provides solutions to heat and water management problems engineers must face when designing and implementing PEM fuel cells in systems Hundreds of original illustrations, real-life engineering examples, and end-of-chapter problems help clarify, contextualize, and aid understanding
Download or read book Membrane Degradation Mechanisms in Polymer Electrolyte Membrane Fuel Cells written by Vishal Onkarmal Mittal and published by . This book was released on 2006 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Membranes for Low Temperature Fuel Cells written by Surbhi Sharma and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-06-04 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Membranes for Low Temperature Fuel Cells provides a comprehensive review of novel and state-of-the-art polymer electrolyte membrane fuel cells (PEMFC) membranes. The author highlights requirements and considerations for a membrane as an integral part of PEMFC and its interactions with other components. It is an indispensible resource for anyone interested in new PEMFC membrane materials and concerned with the development, optimisation and testing of such membranes. Various composite membranes (polymer and non-polymer) are discussed along with analyses of the latest fi ller materials like graphene, ionic liquids, polymeric ionic liquids, nanostructured metal oxides and membrane concepts unfolding in the field of PEMFC. This book provides the latest academic and technical developments in PEMFC membranes with thorough insights into various preparation, characterisation, and testing methods utilised. Factors affecting proton conduction, water adsorption, and transportation behaviour of membranes are also deliberated upon. Provides the latest academic and technical developments in PEMFC membranes. Reviews recent literature on ex situ studies and in situ single-cell and stack tests investigating the durability (chemical, thermomechanical) and degradation of membranes. Surbhi Sharma, MSc, PhD Working on graphene oxide and fuel cells since 2007, she has published about 50 research articles/book chapters and holds a patent. She has also been awarded various research grants.
Download or read book High temperature polymer electrolyte membrane fuel cells written by Christian Siegel and published by Logos Verlag Berlin GmbH. This book was released on 2015-03-20 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-dimensional computational fluid dynamics model of a high temperature polymer electrolyte membrane fuel cell, employing a high temperature stable polybenzimidazole membrane electrode assembly doped with phosphoric acid, was developed and implemented using a commercially available finite element software. Three types of flow-fields were modeled and simulated. Selected simulation results at reference operating conditions were compared to the performance curves and to segmented solid-phase temperature and current density measurements. For the segmented measurements, an inhouse developed prototype cell was designed and manufactured. The segmented cell was successfully operated and the solid-phase temperature and the current density distribution were recorded, evaluated, and discussed. Sequentially scanned segmented electrochemical impedance spectroscopy measurements were performed to qualitatively support the observed trends. These measurements were used to identify and determine the causes of the inhomogeneous current density distributions. An equivalent circuit model was developed, the obtained spectra were analyzed, and the model parameters discussed. This work helps to provide a better understanding of the internal behaviour of a running high temperature polymer electrolyte membrane fuel cell and presents valuable data for modeling and simulation. For large fuel cells and complete fuel cell stacks in particular, well designed anode and cathode inlet and outlet sections are expected to aid in achieving flatter quantities distributions and in preventing hot spots over the membrane electrode assembly area, and to develop proper start-up, shut-down, and tempering concepts.
Download or read book Development and Application of a Chemical Degradation Model for Reinforced Electrolyte Membranes in Polymer Electrolyte Membrane Fuel Cells written by Sumit Kundu and published by . This book was released on 2008 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cells are electrochemical devices being developed for a variety of consumer applications including homes and vehicles. Before customers will accept this technology fuel cells must demonstrate suitable durability and reliability. One of the most important parts of a fuel cell stack is the polymer electrolyte membrane (PEM). This layer is responsible for conducting protons from anode to cathode and acting as a gas barrier, while operating in a harsh electrochemical environment. In order to develop better and more durable membranes researchers must understand the linkage between the causes of degradation, such as specific material properties and operational conditions. One significant mode of degradation of the electrolyte membrane is through chemical degradation caused by the crossover of reactant gases leading to the formation of peroxide and ultimately radical species. These radicals are able to attack vulnerable groups in the polymer structure of the membrane. The result is membrane thinning, increased gas crossover, fluoride ion release, and voltage degradation. Considerable experimental work has been done to understand these mechanisms, although there has been no attempt to model the connection between the causes of degradation and the physical effects of degradation on the electrolyte membrane. Such a model can be used as a valuable tool when evaluating different degradation mechanisms, developing stronger materials, and enable estimation of the influence of fuel cell operation and system design on degradation. This work presents the development and application of a dynamic semi-mechanistic chemical degradation model for a reinforced membrane in a polymer electrolyte membrane fuel cell. The model was developed using single cell testing with GoreTM PRIMEA® series 5510 catalyst coated membranes under open circuit voltage (OCV) conditions. Such conditions are useful for accelerated testing since they are believed to enhance chemical degradation in membranes since reactant gas partial pressures are at their maximum. It was found that the electrolyte layer closer to the cathode catalyst preferentially degraded. Furthermore, cumulative fluoride release curves for the anode and cathode began to reach plateaus at similar times. The developed model proposes that as the cathode electrolyte layer is degraded, fluoride release slows due to a lack of reactants since the inert reinforcement layer creates a barrier between the cathode and anode electrolyte layers. It is also believed that all fluoride release originates at the degradation site at the cathode. By fitting key parameters, the fluoride release trends were simulated. The proposed model links material properties such as the membrane gas permeability, membrane thickness, and membrane reactivity, as well as operating parameters such as hydrogen partial pressure and relative humidity to fluoride release, thickness change, and crossover. Further investigation into degradation at OCV operation and different relative humidity conditions showed that initial hydrogen crossover measurements were a good indicator of degradation rate over long testing times. The proposed semi-mechanistic model was able to best model the results when using a second order dependence on the hydrogen crossover term. In all cases there was some discrepancy between the model and experimental data after long times. This was attributed to the onset and contribution of anode side degradation. The effect of drawing current on fluoride release was also investigated. Experimental results showed that with increasing current density the fluoride release rate decreased. Using the developed semi-mechanistic model it was proposed that a decrease in hydrogen crossover was primarily responsible for the reduction in chemical degradation of the membrane. A macro-homogeneous model of the anode catalyst layer was used to show that a reduction in hydrogen concentration through the catalyst layer when a current is drawn is a possible reason for the reduction in degradation. Finally the model was applied to three different dynamic drive cycles. The model was able to show that over different drive cycles, the fuel cell will experience different degradation rates. Thus the developed model can be used as a potential tool to evaluate degradation in systems.
Download or read book Fuel Cell Engines written by Matthew M. Mench and published by John Wiley & Sons. This book was released on 2008-03-07 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel Cell Engines is an introduction to the fundamental principles of electrochemistry, thermodynamics, kinetics, material science and transport applied specifically to fuel cells. It covers scientific fundamentals and provides a basic understanding that enables proper technical decision-making.
Download or read book The Chemistry of Membranes Used in Fuel Cells written by Shulamith Schlick and published by John Wiley & Sons. This book was released on 2018-01-02 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Examines the important topic of fuel cell science by way of combining membrane design, chemical degradation mechanisms, and stabilization strategies This book describes the mechanism of membrane degradation and stabilization, as well as the search for stable membranes that can be used in alkaline fuel cells. Arranged in ten chapters, the book presents detailed studies that can help readers understand the attack and degradation mechanisms of polymer membranes and mitigation strategies. Coverage starts from fundamentals and moves to different fuel cell membrane types and methods to profile and analyze them. The Chemistry of Membranes Used in Fuel Cells: Degradation and Stabilization features chapters on: Fuel Cell Fundamentals: The Evolution of Fuel Cells and their Components; Degradation Mechanism of Perfluorinated Membranes; Ranking the Stability of Perfluorinated Membranes Used in Fuel Cells to Attack by Hydroxyl Radicals; Stabilization Mechanism of Perfluorinated Membranes by Ce(III) and Mn(II); Hydrocarbon Proton Exchange Membranes; Stabilization of Perfluorinated Membranes Using Nanoparticle Additives; Degradation Mechanism in Aquivion Perfluorinated Membranes and Stabilization Strategies; Anion Exchange Membrane Fuel Cells: Synthesis and Stability; In-depth Profiling of Degradation Processes in Nafion Due to Pt Dissolution and Migration into the Membrane; and Quantum Mechanical Calculations of the Degradation Mechanism in Perfluorinated Membranes. Brings together aspects of membrane design, chemical degradation mechanisms and stabilization strategies Emphasizes chemistry of fuel cells, which is underemphasized in other books Includes discussion of fuel cell performance and behavior, analytical profiling methods, and quantum mechanical calculations The Chemistry of Membranes Used in Fuel Cells is an ideal book for polymer scientists, chemists, chemical engineers, electrochemists, material scientists, energy and electrical engineers, and physicists. It is also important for grad students studying advanced polymers and applications.
Download or read book Polymer Electrolyte Fuel Cells written by Alejandro A. Franco and published by CRC Press. This book was released on 2016-04-19 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the recent research progress on the fundamental understanding of the materials degradation phenomena in PEFC, for automotive applications. On a multidisciplinary basis, through contributions of internationally recognized researchers in the field, this book provides a complete critical review on crucial scientific topics related
Download or read book PEM Fuel Cell Electrocatalysts and Catalyst Layers written by Jiujun Zhang and published by Springer Science & Business Media. This book was released on 2008-08-26 with total page 1147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton exchange membrane (PEM) fuel cells are promising clean energy converting devices with high efficiency and low to zero emissions. Such power sources can be used in transportation, stationary, portable and micro power applications. The key components of these fuel cells are catalysts and catalyst layers. “PEM Fuel Cell Electrocatalysts and Catalyst Layers” provides a comprehensive, in-depth survey of the field, presented by internationally renowned fuel cell scientists. The opening chapters introduce the fundamentals of electrochemical theory and fuel cell catalysis. Later chapters investigate the synthesis, characterization, and activity validation of PEM fuel cell catalysts. Further chapters describe in detail the integration of the electrocatalyst/catalyst layers into the fuel cell, and their performance validation. Researchers and engineers in the fuel cell industry will find this book a valuable resource, as will students of electrochemical engineering and catalyst synthesis.
Download or read book Boosting Polymer Electrolyte Membrane Fuel Cells from Computational Modeling written by Alejandro A. Franco and published by Academic Press. This book was released on 2018-01-15 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen Energy and Fuel Cell Primers is a series of concise books that present those coming into this broad and multidisciplinary field the most recent advances in each of its particular topics. Its volumes bring together information that has thus far been scattered in many different sources under one single title, which makes them a useful reference for industry professionals, researchers and graduate students, especially those starting in a new topic of research. This volume, Boosting Polymer Electrolyte Membrane Fuel Cells from Computational Modeling, explores the use of multiscale computational modeling tools for the design and optimization of PEM fuel cells. Multiscale modeling is a rapidly emerging simulation approach which can potentially boost the R&D on PEMFCs through the development of an understanding of mechanisms and processes occurring at multiple spatio-temporal scales at multiple levels of materials, such as catalyst, catalyst support and ionomer. The book discusses concrete success stories on the application of this approach and their specific outcomes. It reviews the latest progresses in the field, including some contributions from the author himself. Special focus is given to multiscale modeling of degradation mechanisms and the durability prediction of the cells, as well as water transport and membrane degradation. Prior knowledge of electrochemistry and mathematics is assumed. Explores the available tools for multiscale computational modelling applied to the design optimization of PEM fuel cells through Discusses real world applications and the latest progresses in the field Includes modelling of degradation mechanisms and durability prediction
Download or read book PEM Fuel Cell Testing and Diagnosis written by Jiujun Zhang and published by Newnes. This book was released on 2013-01-22 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: PEM Fuel Cell Testing and Diagnosis covers the recent advances in PEM (proton exchange membrane) fuel cell systems, focusing on instruments and techniques for testing and diagnosis, and the application of diagnostic techniques in practical tests and operation. This book is a unique source of electrochemical techniques for researchers, scientists and engineers working in the area of fuel cells. Proton exchange membrane fuel cells are currently considered the most promising clean energy-converting devices for stationary, transportation, and micro-power applications due to their high energy density, high efficiency, and environmental friendliness. To advance research and development of this emerging technology, testing and diagnosis are an essential combined step. This book aids those efforts, addressing effects of humidity, temperature and pressure on fuel cells, degradation and failure analysis, and design and assembly of MEAs, single cells and stacks. Provides fundamental and theoretical principles for PEM fuel cell testing and diagnosis. Comprehensive source for selecting techniques, experimental designs and data analysis Analyzes PEM fuel cell degradation and failure mechanisms, and suggests failure mitigation strategies Provides principles for selecting PEM fuel cell key materials to improve durability
