Download or read book Understanding the Formation structure functionality Relationship of the Catalyst Layer in a Proton Exchange Membrane Fuel Cell written by Donglei Yang and published by . This book was released on 2021 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton exchange membrane fuel cell (PEMFC) technology provides a sustainable power solution as it electrochemically converts the chemical energy stored in hydrogen molecules into electricity, heat, and water. The electrochemical reactions occurring in the catalyst layer (CL), however, requires the use of precious group metal (PGM) catalysts, such as platinum, which is a major factor contributing to the high cost of PEMFC technology. To reduce the cost, there have been extensive research efforts in developing low-PGM and PGM-free catalyst materials. Nevertheless, the CLs incorporating these novel materials are often found to suffer from severe mass transport resistance resulting in significant performance loss. Based on the literature, this undesired mass transport resistance is mainly attributed to the cathode oxygen transport due to the heterogeneous characteristics of the hierarchical microstructure of the CL. Although a standard CL only contains carbon supported catalyst and ionomer, understanding the formation of the structure and the origin of the structural characteristics have been very challenging due to its complicated preparation process. A CL is usually prepared by an ink casting method, which involves multiple steps. The catalyst ink consists of the CL constituent materials uniformly dispersed in a liquid medium forming a suspension, which has an opaque, heterogeneous, and highly time-sensitive nature making the experimental investigation on the particulate structure in the catalyst ink very challenging. Despite the long history of using the CLs, a principled framework for understanding the structure-property relationship of the CLs has not yet fully developed. To advance the design and development of low-cost and robust CLs, this research 1) conceptualized a physical process capturing the key aspects of the particulate structure formation with respect to the CL fabrication process, 2) based on the complex fluid nature of the catalyst ink, designed a holistic non-destructive hierarchical approach to investigate the particulate structure in the catalyst ink, and 3) qualitatively and experimentally established the formation-structure-process-functionality relationship for CLs. With the newly proposed framework, this research advances current understanding on the structure-property relationship of the CLs and provides novel and practical insights into the design of low-cost functionality-tailored CLs.

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 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 Proton Exchange Membrane Fuel Cells written by David P. Wilkinson and published by CRC Press. This book was released on 2009-11-24 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Detailed, Up-to-Date Treatment of Key Developments in PEMFC MaterialsThe potential to revolutionize the way we power our worldBecause of its lower temperature and special polymer electrolyte membrane, the proton exchange membrane fuel cell (PEMFC) is well-suited for transportation, portable, and micro fuel cell applications. But the performance o

Download or read book Catalyst Layers in Polymer Electrolyte Membrane Fuel Cells written by Jian Zhao and published by . This book was released on 2019 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of the catalyst layers (CLs) has a decisive impact on the performance, durability, and cost of polymer electrolyte membrane (PEM) fuel cells - these are the main technical challenges to the commercialization of PEM fuel cells. The porous CL conventionally consists of carbon-based platinum (Pt/C) and ionomer (Nafion polymer). An ideal CL should maintain the desired structure with sufficient gas diffusion and water removal channels (pores), proton transport media (ionomer), electron travel pathways (catalyst particles), and optimal three-phase boundaries (TPBs) where electrochemical reaction occurs (reaction sites). Practically, the CL is formed during the fabrication process which determines the physical structures, often represented by porosity, mean pore size, pore size distribution (PSD) and specific surface area. The physical structures, in turn, determine the effective transport properties such as effective mass diffusion coefficient and permeability for the reactant in the CLs. However, there is still no clear understanding of what is the optimal structure for the CLs. To investigate the structure of CLs, three aspects are studied in the present thesis work: (i) the effect of fabrication process on the resulting structure, (ii) the effect of the CL structure on its macro-properties, and (iii) the effect of the structure and macro-properties on the mass transport phenomena and the associated cell performance. Many factors including fabrication techniques and CL compositions have a significant impact on the structure formation of CLs. However, how these factors affect the structure is still unclear. Additionally, there lacks experimental characterization of the structure such as porosity, PSD, specific surface area, mean pore size, and surface fractal dimension, as well as mass transport properties such as effective diffusion coefficient and gas permeability for the CLs in literature. With the experimentally determined structural and mass transport parameters of the CLs and the associated electrodes, the mass transport phenomena in PEM fuel cells can be quantitatively analyzed. In the present thesis work, the CL pore structure is experimentally characterized by the method of standard porosimetry (MSP), which is established based on the phenomenon of capillary equilibrium in the wetted porous materials. By the means of MSP, a comprehensive characterization of the structure in terms of porosity, PSD, specific surface area, mean pore size, and surface fractal dimension is obtained. In addition, the effective diffusion coefficient of the CL is studied by the modified Loschmidt Cell, built based on the Fick's law of diffusion. The parameters including effective diffusion coefficient, diffusion resistivity, and its relation with the porosity and mean pore size is investigated. Further, the permeability is measured based on Darcy's law via a custom-engineered apparatus developed in my thesis work. The effect of Pt loading, temperature, flow rate, and gas species is explored in this thesis study. With the experimentally determined pore structure characterization and mass transport properties, a numerical study is performed for the better understanding of the mass transport mechanisms in the porous electrodes. The cell performance conducted in our lab is also reported in the present thesis for a better understanding of the ex-situ experiment and a comparison with the numerical modeling. The experimental and numerical studies presented in the present thesis work is of great significance to (i) understand the structure of the CLs, (ii) to understand the relation between the structure and the mass transport properties such as the effective diffusion coefficient and permeability, and (iii) to understand the effect of the structural parameters and mass transport properties on the mass transport phenomena and hence the cell performance in the PEM fuel cells.

Download or read book Proton Exchange Membrane Fuel Cells written by Inamuddin and published by John Wiley & Sons. This book was released on 2023-02-10 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: PROTON EXCHANGE MEMBRANE FUEL CELLS Edited by one of the most well-respected and prolific engineers in the world and his team, this book provides a comprehensive overview of hydrogen production, conversion, and storage, offering the scientific literature a comprehensive coverage of this important fuel. Proton exchange membrane fuel cells (PEMFCs) are among the most anticipated stationary clean energy devices in renewable and alternative energy. Despite the appreciable improvement in their cost and durability, which are the two major commercialization barriers, their availability has not matched demand. This is mainly due to the use of expensive metal-catalyst, less durable membranes, and poor insight into the ongoing phenomena inside proton exchange membrane fuel cells. Efforts are being made to optimize the use of precious metals as catalyst layers or find alternatives that can be durable for more than 5000 hours. Computational models are also being developed and studied to get an insight into the shortcomings and provide solutions. The announcement by various companies that they will be producing proton exchange membrane fuel cells-based cars by 2025 has accelerated the current research on proton exchange membrane fuel cells. The breakthrough is urgently needed. The membranes, catalysts, polymer electrolytes, and especially the understanding of diffusion layers, need thorough revision and improvement to achieve the target. This exciting breakthrough volume explores these challenges and offers solutions for the industry. Whether for the student, veteran engineer, new hire, or other industry professionals, this is a must-have for any library.

Download or read book Polymer Electrolyte Fuel Cells written by Michael Eikerling and published by CRC Press. This book was released on 2014-09-23 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a systematic and profound account of scientific challenges in fuel cell research. The introductory chapters bring readers up to date on the urgency and implications of the global energy challenge, the prospects of electrochemical energy conversion technologies, and the thermodynamic and electrochemical principles underlying the op

Download or read book Proton Exchange Membrane Fuel Cells written by Alhussein Albarbar and published by Springer. This book was released on 2017-11-17 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the characteristics of Proton Exchange Membrane (PEM) Fuel Cells with a focus on deriving realistic finite element models. The book also explains in detail how to set up measuring systems, data analysis, and PEM Fuel Cells’ static and dynamic characteristics. Covered in detail are design and operation principles such as polarization phenomenon, thermodynamic analysis, and overall voltage; failure modes and mechanisms such as permanent faults, membrane degradation, and water management; and modelling and numerical simulation including semi-empirical, one-dimensional, two-dimensional, and three-dimensional models. It is appropriate for graduate students, researchers, and engineers who work with the design and reliability of hydrogen fuel cells, in particular proton exchange membrane fuel cells.

Download or read book Fully Hydrocarbon Ionomer Catalyst Layers in Proton and Anion exchange Membrane Fuel Cells written by Benjamin Britton and published by . This book was released on 2018 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure and morphology of fuel cell catalyst layers and concomitant system properties, particularly mass transport, were investigated through electrochemical and physical characterization techniques. Catalyst layers designed for proton-exchange membrane fuel cells (PEMFCs) incorporated a hydrocarbon ionomer (sP4c) soluble in low-boiling solvents. These were used to probe the property alterations effected by increasing ionomer coverage within the catalyst layer, and also to measure the impact an extremely small quantities (0.38 wt%) of a commonly employed high-boiling solvent, DMF, in the catalyst ink. High-boiling solvents are difficult to eliminate during electrode formation, and resultant solvent-annealed catalyst layers lost electrocatalytic surface area, resulting in markedly greater kinetic losses compared to catalyst layers formed without high-boiling solvents. Catalyst layers designed for anion-exchange membrane fuel cells (AEMFCs) incorporating hydrocarbon ionomer in the catalyst layer (FAA-3) requiring high-boiling solvent (NMP, 2.3 wt% of total solvent) were formed over a broad array of conditions. Catalyst layers formed slowly at high temperatures to drive off high-boiling solvent displayed significantly enhanced mesoporosity, relating to enhanced transport characteristics, over solvent-annealed analogues with low mesoporosity, despite comparable total volumes. The impacts of solvent annealing on AEMFC electrode properties and resultant achievable power density and degradation were disproportionate compared to the similar PEMFC study. A new methodology for fuel cell membrane-electrode assembly construction, direct membrane deposition (DMD), enables lower interfacial resistances and enhanced water transport for a given thickness of membrane. These are desired properties for both PEMFCs and AEMFCs. Initially developed with inkjet printers designed for single-cell biological printing applications, this method was adapted to spray-coating systems in order to address issues with fuel and electrical crossover, suitability for hydrocarbon ionomers, and scalability / large-scale reproducibility. A perfluorinated sulfonic acid ionomer reference material (Nafion D520) was employed for direct comparison to initial methods. Highly reproducible DMDs with low fuel and electrical crossover resulted.

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 A Characterization Study on Catalyst Layers in Proton Exchange Membrane Fuel Cells written by Luyue Li and published by . This book was released on 2016 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the work for the catalyst layer (CL) characterization study of proton exchange membranes (PEM) for fuel cells. In particular, both the structure and performance of catalyst layers with alternative ionomers were studied. Structure wise, the morphology, surface area and pore size distribution studies were accomplished with scanning electron microscopy (SEM), transmission electron microscope (TEM) and nitrogen adsorption processed through Brunauer--Emmett--Teller (BET) and Barrett- Joyner-Halenda (BJH) theory. Water uptake isotherms of the CLs have been developed under well controlled relative humidity (RH) levels. The performance characterization focuses on polarization study, catalyst layer proton conductivity measurement and estimation of the proton conduction tortuosity. Also, a thermal investigation between various components of the catalyst layer was performed. Two different sets of CLs were examined, the in-house fabricated 3M ionomer CLs and free-standing 3M CLs directly provided from the 3M Company. A characteristic comparison of the structure and electrochemical performance have been carried out, along with further discussion on the formation of CLs containing 3M polytetrafluoroethylene (PTFE) ionomer. Our data revealed that higher ionomer to carbon (I/C) ratio reduced the amount of micro- , meso- and macropores. This allowed the construction of a more completely developed ionic transport network, however, could potentially hinder the mass transfer. Also, our study showed that higher Pt:C ratio lead to a more intense Pt agglomeration. The CL's porosity was strongly affected by such Pt clustering. Furthermore, energy dispersive X-ray analysis (EDS) revealed that the 3M ionomer preferred attaching to the carbon surface over the Pt particles. According to our polarization study, in contrast of tradition Nafion fuel cells, the 3M fuel cells reached its optimal performance at 60%-70% RH and suffered dramatic mass transfer losses at saturated humidity level. Therefore, the 3M fuel cells are able to function fully under drier conditions than the Nafion units. However, the high sensitivity on the cells' water content requires efficient water management during operation, especially at higher current density. Polarization study also showed an optimal 3M ionomer loading of 36 wt.% at 30:70 Pt:C ratio, which is similar to traditional Nafion fuel cells.

Download or read book PEM Fuel Cells written by Yun Wang and published by Momentum Press. This book was released on 2013-04-06 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer Electrolyte Membrane (PEM) fuel cells convert chemical energy in hydrogen into electrical energy with water as the only by-product. Thus, PEM fuel cells hold great promise to reduce both pollutant emissions and dependency on fossil fuels, especially for transportation—passenger cars, utility vehicles, and buses—and small-scale stationary and portable power generators. But one of the greatest challenges to realizing the high efficiency and zero emissions potential of PEM fuel cells technology is heat and water management. This book provides an introduction to the essential concepts for effective thermal and water management in PEM fuel cells and an assessment on the current status of fundamental research in this field. The book offers you: • An overview of current energy and environmental challenges and their imperatives for the development of renewable energy resources, including discussion of the role of PEM fuel cells in addressing these issues; • Reviews of basic principles pertaining to PEM fuel cells, including thermodynamics, electrochemical reaction kinetics, flow, heat and mass transfer; and • Descriptions and discussions of water transport and management within a PEM fuel cell, including vapor- and liquid-phase water removal from the electrodes, the effects of two-phase flow, and solid water or ice dynamics and removal, particularly the specialized case of starting a PEM fuel cell at sub-freezing temperatures (cold start) and the various processes related to ice formation.

Download or read book Proton Conducting Membrane Fuel Cells IV written by and published by The Electrochemical Society. This book was released on 2006 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Fuel Cells written by Xianguo Li and published by CRC Press. This book was released on 2005-12-22 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is engineering oriented and covers a large variety of topics ranging from fundamental principles to performance evaluation and applications. It is written systematically and completely on the subject with a summary of state-of-the-art fuel cell technology, filling the need for a timely resource. This is a unique book serving academic researchers, engineers, as well as people working in the fuel cell industry. It is also of substantial interest to students, engineers, and scientists in mechanical engineering, chemistry and chemical engineering, electrochemistry, materials science and engineering, power generation and propulsion systems, and automobile engineering.

Download or read book Pore scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells PEMFCs written by Weibo Zheng (Ph. D. in mechanical engineering) and published by . This book was released on 2019 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the complex phenomena occurring inside the catalyst layer of a proton exchange membrane fuel cell (PEMFC) is critical to design of an optimized structure with low platinum loading and high performance. Describing detailed physical and chemical processes in the catalyst layer at the resolution of pore scale, pore-scale simulation is considered as a promising approach for use in understanding the structure-performance relation and subsequent optimization of the catalyst layer. For wide spread use in industry, the computational cost of pore-scale simulation needs to be reduced. To achieve this goal, a multiscale decomposition method that accelerates the convergence of an iteratively-solved variable distribution in porous electrodes is proposed. The multiscale method combines the macroscopic method with pore-scale simulation by decomposing a variable distribution into the macroscopic component and local fluctuations. The decomposition removes the slowly converged, long wavelength components in an iteratively-solved variable distribution, thereby accelerating the convergence. In this research, to reduce the computational cost of multiphase pore-scale simulation, the multiscale method is applied to the electrolyte phase potential and oxygen concentration, both of which converge slowly and limit the overall computational efficiency. The results show that the multiscale method can substantially accelerate the convergence without sacrificing the accuracy. It is also found that the estimation of the effective transport property appearing in the volume-averaged part of the multiscale method influences the convergence rate of the multiscale method. With more accurate estimation of an effective transport property, the multiscale method is shown to work more effectively, especially for a thick porous electrode. Being an important parameter in the application to oxygen concentration, the effective oxygen diffusivity in pores is systematically investigated using pore-scale simulation, and empirical correlations for use in the multiscale method, as well as other macroscopic simulation methods, are obtained. The emphasis is placed on the importance of Knudsen diffusion in nanoscale pores in the catalyst layer. The results also highlight the importance of liquid water distribution on the effective diffusivity estimation and, therefore, on the computational efficiency of the multiscale method. With reduced computational cost, multiphase pore-scale simulation of a catalyst layer used in a laboratory experiment is successfully performed. The proposed multiscale decomposition method can be extended to pore-scale simulation for any porous electrodes.

Download or read book Proton Exchange Membrane Fuel Cells written by Hui Li and published by CRC Press. This book was released on 2010-04-14 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-scale commercialization of proton exchange membrane fuel cell (PEMFC) technology has been hindered by issues of reliability, durability, and cost, which are all related to the degradation of fuel cell performance. This degradation often has root causes in contamination from fuel, air streams, or system components. With contributions from inte

Download or read book Thin film Catalysts for Proton Exchange Membrane Water Electrolyzers and Unitized Regenerative Fuel Cells written by Peter Kúš and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work revolves around the hydrogen economy and energy-storage electrochemical systems. More specifically, it investigates the possibility of using magnetron sputtering for deposition of efficient thin-film anode catalysts with low noble metal content for proton exchange membrane water electrolyzers (PEM-WEs) and unitized regenerative fuel cells (PEM-URFCs). The motivation for this research derives from the urgent need to minimize the price of such electrochemical devices should they enter the mass production. Numerous experiments were carried out, correlating the actual in-cell performance with the varying position of thin-film catalyst within the membrane electrode assembly, with the composition of high-surface support sublayer and with the chemical structure of the catalyst itself. The wide arsenal of analytical methods ranging from electrochemical impedance spectroscopy through electrochemical atomic force microscopy to photoelectron spectroscopy allowed the description ofthe complex phenomena behind different obtained efficiencies. Systematic optimizations led to the design of a novel PEM-WE anode thin-film iridium catalyst which performs similarly to the standard counterparts despite using just a fraction of their noble metal content. Moreover, the layer-by-layer approach resulted in the design of a Ir/TiC/Pt bi-functional anode for PEM-URFC which is able to operate in both the fuel cell and electrolyzer regime and thus helps to cut the cost of the whole conversion system even further.