Download or read book Control of Ionomer Distribution in Roll to Roll Coated Fuel Cell Catalyst Layers written by and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cell catalyst layers are a complex mixture of catalyst particles and ion-conducting polymers. The performance of catalyst layers is highly dependent on microstructure, which must balance proton and electron conduction with gas transport. As fuel cells transition from the laboratory to industrial production for vehicles and other applications, there is a need to understand how manufacturing processes impact the microstructure and, ultimately, the performance of catalyst layers. In this work, we have focused on the roll-to-roll coating of catalyst layers for proton exchange membrane fuel cells. The catalyst layers are responsible for the electrochemical reactions that enable power production. In these devices the catalyst is commonly a Pt nanoparticle supported on porous carbon blacks. The ion conducting polymer, or ionomer, is typically a perfluorosulfonic acid. The most common being Nafion. To fabricate the catalyst layer, the catalyst particles are dispersed in an ink with the ionomer and cast to form the catalyst layer. Commonly, laboratory samples are prepared using spray coating or hand painting, which effectively coat many thin layers to achieve the desired catalyst layer thickness. This creates catalyst layers with uniform distributions of materials throughout the thickness of the full catalyst layer. In contrast, roll-to-roll methods, like slot die, gravure or screen printing, coat the catalyst layer as a single wet film. As the film dries, ink constituents are able to segregate, leading to a heterogeneous distribution of materials through the thickness of the layer. It is also known that the choice of solvent and drying rate can affect the morphology of the catalyst layer. Thus, there is a need to understand how ink formulation and the drying process influence the distribution of materials and catalyst layer morphology. Here, we have explored the influence of solvent and drying rate on morphology of roll-to-roll coated catalyst layers. We show the development of the Kelvin probe method as a rapid screening technique for qualitative analysis of ionomer distribution. We also utilize nano X-ray computed tomography to visualize electrode structure and to quantify particle-size and pore-size distributions, thickness-dependent ionomer distribution, tortuosity, and effective transport properties. We find that solvent has a strong influence on ionomer distribution, with less of an effect on porosity. Conversely, drying temperature has a strong influence on porosity, but less influence on ionomer distribution. Finally, we utilize in situ fuel cell performance testing and other advanced diagnostics to quantify the impact of catalyst layer properties on fuel cell performance and demonstrate that roll-to-roll coating is capable of coating high performance catalyst layers in multi-meter lengths.
Download or read book Control of Ionomer Distribution and Porosity in Roll to Roll Coated Fuel Cell Catalyst Layers written by and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As fuel cells transition from the laboratory to industrial production for vehicles and other applications there is a need to understand how manufacturing processes impact the properties and, ultimately, the performance of materials. Roll-to-roll coating enables processing at meters per second speeds with physics that can be quite different from common laboratory coating methods. In this work, we have focused on the coating of catalyst layers for proton exchange membrane fuel cells. Commonly, laboratory samples are prepared using spray coating or hand painting, which effectively coat many thin layers to achieve the desired catalyst layer thickness. This creates catalyst layers with uniform distributions of materials throughout the thickness of the full catalyst layer. In contrast, roll-to-roll methods, like slot die and gravure, coat the catalyst layer as a single wet film. As the film dries, ink constituents are able to segregate, leading to a heterogeneous distribution of materials through the thickness of the layer. It is also known that solvent and drying rate can affect the morphology of the catalyst layer. Thus, there is a need to understand how ink formulation and the drying process influence the distribution of materials and catalyst layer morphology. Here, we have explored the influence of solvent and drying rate on morphology of roll-to-roll coated catalyst layers. We show the development of the Kelvin probe method as a rapid screening technique for qualitative analysis of ionomer distribution. We also utilize nano X-ray computed tomography to visualize electrode structure and to quantify particle-size and pore-size distributions, thickness-dependent ionomer distribution, tortuosity, and effective transport properties. We find that solvent has a strong influence on ionomer distribution, with less of an effect on porosity. Conversely, drying temperature has a strong influence on porosity, but less influence on ionomer distribution. Finally, we utilize in situ fuel cell performance testing and other advanced diagnostics to quantify the impact of catalyst layer properties on fuel cell performance and demonstrate that roll-to-roll coating is capable of coating high performance catalyst layers in multi-meter lengths. have focused on the coating of catalyst layers for proton exchange membrane fuel cells. Commonly, laboratory samples are prepared using spray coating or hand painting, which effectively coat many thin layers to achieve the desired catalyst layer thickness. This creates catalyst layers with uniform distributions of materials throughout the thickness of the full catalyst layer. In contrast, roll-to-roll methods, like slot die and gravure, coat the catalyst layer as a single wet film. As the film dries, ink constituents are able to segregate, leading to a heterogeneous distribution of materials through the thickness of the layer. It is also known that solvent and drying rate can affect the morphology of the catalyst layer. Thus, there is a need to understand how ink formulation and the drying process influence the distribution of materials and catalyst layer morphology. Here, we have explored the influence of solvent and drying rate on morphology of roll-to-roll coated catalyst layers. We show the development of the Kelvin probe method as a rapid screening technique for qualitative analysis of ionomer distribution. We also utilize nano X-ray computed tomography to visualize electrode structure and to quantify particle-size and pore-size distributions, thickness-dependent ionomer distribution, tortuosity, and effective transport properties. We find that solvent has a strong influence on ionomer distribution, with less of an effect on porosity. Conversely, drying temperature has a strong influence on porosity, but less influence on ionomer distribution. Finally, we utilize in situ fuel cell performance testing and other advanced diagnostics to quantify the impact of catalyst layer properties on fuel cell performance and demonstrate that roll-to-roll coating is capable of coating high performance catalyst layers in multi-meter lengths.
Download or read book Influence of Coating Method on the Performance of Roll to Roll Coated PEM Fuel Cell Catalyst Layers written by and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As production of fuel cell vehicles and power systems increases there is a need to understand the process science of fuel cell manufacturing. Industrial production of polymer electrolyte membrane fuel cell (PEMFC) electrodes will rely on continuous roll-to-roll (R2R) coating methods to meet the rates needed for mass production. There are a variety of coating methods that could be used to coat catalyst layers. The different physics of each method may result in different morphologies and performance. Here we present the results of a study comparing fuel cell catalyst layers coated using two R2R coating methods: slot-die and gravure. These two methods were selected because the physics of applying the liquid to the substrate is very different between the two cases. Pt/C catalysts layers were coated directly onto carbon-fiber gas diffusion media to create gas diffusion electrodes (GDEs), without the use of a decal transfer process. These GDEs were assembled into membrane electrode assemblies (MEAs) by hot pressing to Nafion membranes. In situ performance and other electrochemical diagnostics were used to determine the influence of coating method on catalyst layer electrochemical properties. Electron microscopy was utilized to understand the influence of coating method on electrode morphology and its influence on electrochemical properties. We also explored the influence of solvent ratio to understand the potential coupling between ink formulation and coating methodology.
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 Coating and Drying Defects written by Edgar B. Gutoff and published by John Wiley & Sons. This book was released on 2006-08-25 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical guide for ensuring a defect-free coating and drying process For professionals in the coating and drying industry, the world is a demanding place. New, technically complex products such as fuel cell membranes, thin film batteries, solar cells, and RFID chips require coatings of extreme precision. With the bar raised so high, understanding how to troubleshoot and eliminate defects on a coating line is an essential skill for all personnel. Coating and Drying Defects, Second Edition provides manufacturing and quality control personnel, equipment operators and supervisors, and plant engineers and scientists with the full complement of proven tools and techniques for detecting, defining, and eliminating coating defects and operating problems, and for ensuring that they do not recur. Updating the valuable contents of the first edition, this practical Second Edition: Describes all major processes for coating and drying of continuous film on sheets or webs Covers technologies that have been recently developed to prevent defect formation and improve operating procedures Provides a rational framework within which to assess and analyze virtually any defect that may arise Offers step-by-step guidelines for conducting every phase of the troubleshooting process, including defect prevention Going beyond simply describing a disparate set of troubleshooting techniques, this unique guide arms readers with a systematic, nonmathematical methodology encompassing the entire coating operation, becoming an indispensable resource for manufacturing and quality-control personnel as well as plant engineers, polymer scientists, surface scientists, organic chemists, and coating scientists.
Download or read book Liquid Film Coating written by P.M. Schweizer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multi-authored volume provides a comprehensive and in-depth account of the highly interdisciplinary science and technology of liquid film coating. The book covers fundamental principles from a wide range of scientific disciplines, including fluid mechanics aand transport phenomena, capillary hydrodynamics, surface and colloid science. The authors, all acknowledged eperts in their fields, represent a balance between industrial and academic points of view. Throughout the text, many case studies illustrate how scientific principles together with advanced experimental and theoretical methods are applied to develop and optimize manufacturing processes of eve increasing sophiatication and efficiency. In the first part of the book, the authors systematically recount the underlying physical principles and important material properties. The second part of the book gives a comprehensive overview of the most advanced experimental, mathematical and computational methods available today to investigate coating processes. The third part provides an overview and critical literature review for all major classes of liquid film coating processes of industrial importance.
Download or read book Nanoscale Phenomena in Ultrathin Catalyst Layers of PEM Fuel Cells written by Amin Nouri Khorasani and published by . This book was released on 2013 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ionomer-free ultrathin catalyst layers have shown promise to enhance the performance and reduce the platinum loading of catalyst layers in polymer electrolyte fuel cell. The nanostructure of a catalyst layer affects the distribution and diffusion of reactants, and consequently its effectiveness factor. We employed classical molecular dynamics to simulate a catalyst layer pore as a water-filled channel with faceted walls, and investigated the effect of channel geometry and charging on hydronium ion and water distribution and diffusion in the channel. Equilibrium hydronium ion distribution profiles on the catalyst channel were obtained to calculate the effect of channel structure on the electrostatic effectiveness factor of the channel. Furthermore, we calculated the self-diffusion coefficient and interfacial water structure in the model channel. Results on proton concentration, diffusion and kinetics are discussed in view of catalyst layer performance.
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 Thin Film Cathode Catalysts for Polymer Electrolyte Fuel Cells and Investigation of the Role of Ionomer in the Polymer Electrolyte Fuel Cell Catalyst Layer written by Ruhulla Shaik and published by . This book was released on 2006 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Improving the Efficiency of Fully Hydrocarbon based Proton exchange Membrane Fuel Cells by Ionomer Content Gradients in Cathode Catalyst Layers written by Hien Nguyen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Recently, the cell performances of fully hydrocarbon-based fuel cells approached those of cells with perfluorinated ionomers. Most studies used a low catalyst layer ionomer content (∼10 wt%) to enable the highest performance. However, such low ionomer contents can cause a lower cell performance, especially under application-relevant, i.e. reduced humidities (≤50% relative humidity). This work systematically investigates ionomer content gradients in cathode catalyst layers based on hydrocarbon ionomer. A graded ionomer content in the catalyst layer with a higher ionomer content in the vicinity of the membrane (I/C = 0.4, 25% of total layer) and a lower ionomer content (I/C = 0.2, 75% of entire layer) near the gas diffusion layer was found to ensure sufficient proton conductivity without compromising reactant transport. In single-cell tests at hot and dry operation conditions (H2/air, 95 °C and 50% RH), the graded layer enabled both significantly improved current density at relevant cell potentials vs. a monolithic catalyst layer (496 mA cm−2vs. 367 mA cm−[email protected] V) and slightly increased peak performance (0.76 W cm−2vs. 0.71 W cm−2). Under the given conditions, the performance of the graded layer is similar to that of a Nafion catalyst layer. At 80% RH, the hydrocarbon-graded catalyst layer outperforms the Nafion catalyst layer at high current densities
Download or read book Preparation Characterization Properties and Application of Nanofluid written by I. M. Mahbubul and published by William Andrew. This book was released on 2018-09-20 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preparation, Characterization, Properties and Application of Nanofluid begins with an introduction of colloidal systems and their relation to nanofluid. Special emphasis on the preparation of stable nanofluid and the impact of ultrasonication power on nanofluid preparation is also included, as are characterization and stability measurement techniques. Other topics of note in the book include the thermophysical properties of nanofluids as thermal conductivity, viscosity, and density and specific heat, including the figure of merit of properties. In addition, different parameters, like particle type, size, concentration, liquid type and temperature are discussed based on experimental results, along with a variety of other important topics. The available model and correlations used for nanofluid property calculation are also included. Provides readers with tactics on nanofluid preparation methods, including how to improve their stability Explores the effect of preparation method and stability on thermophysical and rheological properties of nanofluids Assesses the available model and correlations used for nanofluid property calculation
Download or read book PEM Water Electrolysis written by Dmitri Bessarabov and published by Academic Press. This book was released on 2018-08-04 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: PEM Water Electrolysis, a volume in the Hydrogen Energy and Fuel Cell Primers series presents the most recent advances in the field. It brings together information that has thus far been scattered in many different sources under one single title, making it a useful reference for industry professionals, researchers and graduate students. Volumes One and Two allow readers to identify technology gaps for commercially viable PEM electrolysis systems for energy applications and examine the fundamentals of PEM electrolysis and selected research topics that are top of mind for the academic and industry community, such as gas cross-over and AST protocols. The book lays the foundation for the exploration of the current industrial trends for PEM electrolysis, such as power to gas application and a strong focus on the current trends in the application of PEM electrolysis associated with energy storage. Presents the fundamentals and most current knowledge in proton exchange membrane water electrolyzers Explores the technology gaps and challenges for commercial deployment of PEM water electrolysis technologies Includes unconventional systems, such as ozone generators Brings together information from many different sources under one single title, making it a useful reference for industry professionals, researchers and graduate students alike
Download or read book Hydrogen and Fuel Cell written by Johannes Töpler and published by Springer. This book was released on 2015-12-20 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces readers to hydrogen as an essential energy carrier for use with renewable sources of primary energy. It provides an overview of the state of the art, while also highlighting the developmental and market potential of hydrogen in the context of energy technologies; mobile, stationary and portable applications; uninterruptible power supplies and in the chemical industry. Written by experienced practitioners, the book addresses the needs of engineers, chemists and business managers, as well as graduate students and researchers.
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 Polymer Electrolyte Fuel Cells written by Alejandro A. Franco and published by CRC Press. This book was released on 2013-07-09 with total page 618 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 to PEFC materials degradation, and ensures a strong balance between experimental and theoretical analysis and preparation techniques with several practical applications for both the research and the industrial communities.
Download or read book Factors Influencing Electrochemical Properties and Performance of Hydrocarbon Based Ionomer PEMFC Catalyst Layers written by Toby Duncan Astill and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work investigated the properties of catalyst layers for proton exchange membrane fuel cells (PEMFC) that contained sulfonated poly(ether ether ketone) (SPEEK). A series of SPEEK polymers were prepared with varying ion exchange capacity (IEC) to test their oxygen mass transport properties, electrochemical kinetic parameters, proton conductivity, and water sorption characteristics. A simple method to fabricate catalyst layers containing SPEEK and polytetrafluoroethylene (PTFE) was developed. Catalyst layers were analyzed using scanning electron microscopy (SEM), mercury porosimetry and contact angle determination. Electrochemical characterization in an operating fuel cell was performed using current-potential polarization, cyclic voltammetry, and electrochemical impedance spectroscopy. Electrochemical oxygen reduction in SPEEK membranes was examined in a solid-state electrochemical cell, which allowed determination of oxygen mass transport properties and kinetic parameters. The oxygen diffusion coefficient and permeability was found to increase with increasing ion exchange capacity (IEC), while the solubility of oxygen correspondingly decreased, these trends are due to an increase in water content with increasing IEC. In comparison to perfluorinated electrolytes, such as Nafion®, SPEEK exhibited a lower permeability of oxygen due to a considerably lower solubility of oxygen. A decrease in fuel cell performance was observed when SPEEK was employed in the cathode catalyst layer as the proton conducting medium. The fuel cell current density showed a strong dependence on the method of fabrication of the catalyst layer and the content of SPEEK. Compared to Nafion®-based catalyst layers, SPEEK catalyst layers were found to suffer from low electrochemically active surface area (ESA) and low ionic conductivity. The weight content of SPEEK electrolyte was found to strongly influence the mass transport limited current density.
