This research addresses the manufacturing problems of the fuel cell in an applied industrial approach with the aim of investigating the technology of manufacturing of Proton Exchange Membrane (PEM) fuel cells, and using this technology in reducing the cost of manufacturing through simplifying the design and using less exotic materials. The first chapter of this thesis briefly discusses possible energy alternatives to fossil fuels, arriving at the importance of hydrogen energy and fuel cells. The chapter is concluded with the main aims of this study. A review of the relevant literature is presented in chapter 2 aiming to learn from the experience of previous researchers, and to avoid the duplication in the current work. Understanding the proper working principles and the mechanisms causing performance losses in fuel cells is very important in order to devise techniques for reducing these losses and their cost. This is covered in the third chapter of this thesis which discusses the theoretical background of the fuel cell science. The design of the fuel cell module is detailed in chapter 4, supported with detailed engineering drawings and a full description of the design methodology. So as to operate the fuel cell; the reactant gases had to be prepared and the performance and operating conditions of the fuel cell tested, this required a test facility and gas conditioning unit which has been designed and built for this research. The details of this unit are presented in chapter 5. In addition to the experimental testing of the fuel cell under various geometric arrangements, a three dimensional 3D fully coupled numerical model was used to model the performances of the fuel cell. A full analysis of the experimental and computational results is presented in chapter 6. Finally, the conclusions of this work and recommendations for further investigations are presented in chapter 7 of this thesis. In this work, an understanding of voltage loss mechanism in the fuel cell based on thermodynamic irreversibility is introduced for the first time and a comprehensive formula for efficiency based on the actual operating temperature is presented. Furthermore, a novel design of a 100W (PEMFC) module which is apt to reduce the cost of manufacturing and improve water and thermal management of the fuel cell is presented. The work also included the design and manufacturing of a test facility and gas conditioning unit for PEM fuel cells which will be useful in performing further experiments on fuel cells in future research work. Taking into consideration that fuel cell technology is not properly revealed in the open literature, where most of the work on fuel cells does not offer sufficient information on the design details and calculations, this thesis is expected to be useful in the manifestation of fuel cell technology. It is also hoped that the work achieved in this study is useful for the advancement of fuel cell science and technology.

Proton exchange membrane fuel cell (PEMFC) is a potential alternative energy conversion device for stationary and automotive applications. Wide commercialization of PEMFC depends on progress that can be achieved to enhance its reliability and durability along with cost reduction. It is desirable to operate the PEMFC at uniform local current density and temperature distributions over the surface of the membrane electrode assembly (MEA). Non-uniform distributions of both current and temperature over the MEA could result in poor reactant and catalyst utilization as well as overall cell performance degradation. Local current distribution in the PEMFC electrodes are closely related to operating conditions, but it is also affected by the organization of the reactant flow arrangements in PEMFCs. Reactant depletion and water formation along the flow channel leads to current variation from the channel inlet to the exit, which leads to non-uniformity of local electrochemical reaction activity, and degradation of the cell performance. Flow arrangements between the anode and cathode streams, such as co-, counter- and cross- flow can exacerbate the effect of the non-uniformity considerably, producing complex current distribution patterns over the electrode surfaces. Thus, understanding of the local current density and its spatial characteristics, as well as the temperature distributions under different physical and operating conditions, is crucially important in order to develop optimum design and operational strategies. Despite the importance of the influence of the flow arrangement on the local current and temperature distributions under various operating conditions, few systematic studies have been conducted experimentally to investigate this effect. In this research, an experimental setup with special PEMFC test cells are designed and fabricated in-house, in order to conduct in-situ mapping of the local current and temperature distributions over the electrode surfaces. A segmented flow field plate and the printed circuit board (PCB) technique is used to measure the current distribution in a single PEMFC. In situ, nondestructive temperature measurements are conducted using thermocouples to determine the actual temperature distribution. Experimental studies have been conducted to investigate the effect of different flow arrangements between the anode and cathode (co-, counter-, and cross- flow) on the local current density distribution over the MEA surface. Furthermore, local current distribution has been characterized for PEMFCs under various operating conditions such as reactant stoichiometry ratios, reactant backpressure, cell temperature, cell potentials, and relative humidity for each one of the reactant flow arrangements. The dynamic characteristics of the local current in PEMFC under different operating conditions also have been studied. Temperature distributions along the parallel and serpentine flow channels in PEMFs under various operating conditions are also investigated. All independent tests are conducted to identify and optimize the key design and operational parameters for both local current and temperature distributions. It has been found that the local current density distribution is strongly affected by the flow arrangement between the anode and cathode streams and the key operating conditions. It has also been observed that the counter-flow arrangement generates the most uniform distribution for the current density, whereas the co-flow arrangement results in a considerable variation in the current density from the reactant gas stream inlet to the exit. Low stoichiometry ratio of hydrogen at the anode side has a predominant effect on the current distribution and cell performance. Further, it has been found that the dynamic characteristics and the degree of fluctuation of local current density inside PEMFC are strongly influenced by the crucial operating conditions. In-situ, nondestructive temperature measurements indicate that the temperature distribution inside the PEMFC is strongly sensitive to the cell’s current density. The temperature distribution inside the PEMFC seems to be virtually uniform at low current density, while the temperature variation increases up to 2 oC at the high current density. Finally, the present work contribution related to the local current and temperature distributions is required to understand the effect of each individual or even several operating parameters combined together on the local current and temperature distributions. This will help to develop an optimum design, which leads to enhancing the reliability and durability in operational PEMFCs.

This research mainly investigated how the hydrophilic and hydrophobic properties of gas diffusion layer, and the different open ratio of the flowfield may affect the performance of the micro proton exchange membrane fuel cell (£gPEMFC). The flow plate used in this experiment was made through deep UV lithography manufacturing processes and micro-electroforming manufacturing processes. Four different open ratios, 52.8 %, 50.8 %, 75.2 % and 75.75 %, of the flowfield were designed for the flow plate composed of serpentine-parallel and serpentine geometrical micro configurations. Acrylic (PMMA: Polymethylmethacrylate) was used to make the terminal plate placed on both sides of the micro proton exchange membrane fuel cell. By varying values of the hydrophilic and hydrophobic properties of the anode gas diffusion layer, the effects of these two parameters on the polarization curve and power density of the cell were explored. All results obtained in the experiment are presented by P-I curve and V-I curve. The experiment results show that, with 1: 5 flow ratio of anode to cathode, a design with the gas diffusion layer made of the material with hydrophobic factor 20 wt.% and with open ratio of 50.8 % for anode flow channel as well as open ratio of 75.75 % for cathode flow channel may have the best performance.

The characteristics of the proton exchange membrane fuel cell (called PEMFC) stacks made with the graphite unipolar/bipolar plates are studied in this thesis. Using pure hydrogen as fuel, certain experimental work is conducted to help us to understand the factors which influence on the performance of a HFC stack. The experimental work under various operating conditions starts from single cell stacks to multi-cell stacks. The maximum power is about 200 W, which is made with two 10-cell stacks in series. For simplification, all of the flow channels in the cathode are open type in which air is directly supplied from ambient by fan. The comparison of the performance of two single cells, which are made with both a graphite unipolar plate and a new-type carbon fiber unipolar plate, is conducted. The total resistances of the two types of bipolar plates with gas diffusion layers are tested to help us to understand their strong or weak points. The experimental results display that the double inlets has better performance than the single inlet due to larger entrance space. Increasing the applied torque will reduce the contact resistance between bipolar plate and diffusion layer and also the gaps between the fibers of carbon cloth. Reducing the contact resistance is helpful in increasing the performance of the cell, but reducing the gaps between fibers will inhibit the entering of reactive gas and is unfavorable for performance; therefore, the proper torque is necessary to obtain the best voltage output. When air is used as an oxidizer and the flow channel is an open type channel, the fan in high rotating speed is helpful at high current density. The high air volume flow rate can supply sufficient oxidizer and avoid the decay of the voltage output at high current density. At the current density 1 A/cm2, the power density of the single-cell stack is about 400 mW/cm2 and the power density of the 10-cell stack is down to about 310 mW/cm2 in our experiment. The rib of the carbon fiber unipolar/bipolar plate is soft, so there is no deformation in the gas diffusion layer in stack assembly. Only slight compression is needed to assemble a stack; therefore, the reactive gas can easily flow into the most of active area. This type unipolar/bipolar plate is made with low density plastic except that the rib is made with carbon fiber bunches. Thus the new plate is weight light, cost low and volume small. So it is quite possible that the new-type of carbon fiber plate is used as substitution for the graphite bipolar plate in the future. In that case the light, low cost and high performance choice can be achieved.

It is desirable to increase the operation temperature of proton exchange membrane fuel cells above 100oC due to fast electrode kinetics, high tolerance to fuel impurities and simple thermal and water management. In this study / the objective is to develop a high temperature proton exchange membrane fuel cell. Phosphoric acid doped polybenzimidazole membrane was chosen as the electrolyte material. Polybenzimidazole was synthesized with different molecular weights (18700-118500) by changing the synthesis conditions such as reaction time (18-24h) and temperature (185-200oC). The formation of polybenzimidazole was confirmed by FTIR, H-NMR and elemental analysis. The synthesized polymers were used to prepare homogeneous membranes which have good mechanical strength and high thermal stability. Phosphoric acid doped membranes were used to prepare membrane electrode assemblies. Dry hydrogen and oxygen gases were fed to the anode and cathode sides of the cell respectively, at a flow rate of 0.1 slpm for fuel cell tests. It was achieved to operate the single cell up to 160oC. The observed maximum power output was increased considerably from 0.015 W/cm2 to 0.061 W/cm2 at 150oC when the binder of the catalyst was changed from polybenzimidazole to polybenzimidazole and polyvinylidene fluoride mixture. The power outputs of 0.032 W/cm2 and 0.063 W/cm2 were obtained when the fuel cell operating temperatures changed as 125oC and 160oC respectively. The single cell test presents 0.035 W/cm2 and 0.070 W/cm2 with membrane thicknesses of 100 &micro / m and 70 &micro / m respectively. So it can be concluded that thinner membranes give better performances at higher temperatures.

A mathematical model for a proton exchange membrane fuel cell is the focus of this thesis. Modeling and simulations are carried out with an aim to understand the influence of operational and geometrical parameters on the inner reaction and performance of a proton exchange membrane fuel cell, and discuss the distributions of physical phenomena in membrane and catalyst layer. Than, the results of modeling are compared and analyzed with the experiments, and discuss the reasons of influences of the performance of PEMFC. The results show that activation overpotential is the major reason of influence of the performance at low current density (less than ), and diffusion and ohmic overpotential are substantially increased at high current density (great than ). The membrane of higher membrane conductivity and more thin, increasing pressure of cathode gas and use oxygen can enhance the performance of a PEMFC. The performance almost no influence for the catalyst layer over 0.3£gm. The catalyst layer thin and uniform can decrease coating of this layer. The results of modeling and experiments show that experiments have contact resistance between materials, and the performance slightly lower than performance of modeling, and the differences that at high current density great than low current density.

Proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are two types of low-temperature fuel cells (LTFCs) that operate at temperatures less than 100 °C and are appealing for portable, transportation, and stationary applications. However, commercialization has been hampered by several problems such as cost, efficiency, and durability. New electrocatalysts must be developed that have higher oxygen reduction reaction (ORR) activity, lower precious metal loadings, and improved durability to become commercially viable. This dissertation investigates the development and use of new electrocatalysts for the ORR. Core-shell (shell@core) Pt@Pd[subscript x]Cu[subscript y]/C electrocatalysts, with a range of initial compositions, were synthesized to result in a Pt-rich shell atop a Pd[subscript x]C[subscript y]-rich core. The interaction between core and shell resulted in a delay in the onset of Pt-OH formation, accounting in a 3.5-fold increase in Pt-mass activity compared to Pt/C. The methanol tolerance of the core-shell Pt@PdCu₅/C was found to decrease with increasing Pt-shell coverage due to the negative potential shift in the CO oxidation peak. It was discovered that Cu leached out from the cathode has a detrimental effect on membrane-electrode assembly performance. A spray-assisted impregnation method was developed to reduce particle size and increase dispersion on the support in a consistent manner for a Pd₈₈W₁₂/C electrocatalyst. The spray-assisted method resulted in decreased particle size, improved dispersion and more uniform drying compared to a conventional method. These differences resulted in greater performance during operation of a single DMFC and PEMFC. Additionally, Pd₈₈W₁₂/C prepared by spray-assisted impregnation showed DMFC performance similar to Pt/C with similar particle size in the kinetic region while offering improved methanol tolerance. Pd₈₈W₁₂/C also showed comparable maximum power densities and activities normalized by cost in a PEMFC. Lastly, the activation of aluminum as an effective reducing agent for the wet- chemical synthesis of metallic particles by pitting corrosion was explored along with the control of particle morphology. It was found that atomic hydrogen, an intermediate, was the actual reducing agent, and a wide array of metals could be produced. The particle size and dispersion of Pd/C produced using Al was controlled using PVP and FeCl₂ as stabilizers. The intermetallic Cu₂Sb was similarly prepared with a 20 nm crystallite size for potential use in lithium-ion battery anodes. Lastly, it was found that the shape of Pd produced with Al as a reducing agent could be controlled to prepare 10 nm cubes enclosed by (100) facets with potentially high activity for the ORR. / text

Fuel cell technology has undergone significant development in the past 15 years, spurred in part by its unique energy conversion characteristics; directly converting chemical energy to electrical energy. As fuel cell technology has past through the prototype/pre-commercialisation development, there is increasing interest in manufacturing and application issues. Of the six different fuel cell types pursued commercially, the Proton Exchange Membrane (PEM) fuel cell has received the greatest amount of research and development investment due to its suitability in a variety of applications. A particular application, to which state-of-the art PEMFC technology is suited, is backup/uninterruptible power supply (UPS) systems, or stand-by power systems. The most important feature of any backup/UPS system is reliability. Traditional backup power systems, such as those utilising valve regulated lead acid (VRLA) batteries, employ remote testing protocols that acquire battery state-of-health and state-of-charge information. This information plays a critical role in system management and reliability assurance. A similar testing protocol developed for a PEM fuel cell would be a valuable contribution to the commercialization of these systems for backup/UPS applications. This thesis presents a novel testing and analysis procedure, specifically designed for a PEM fuel cell in a backup power application. The test procedure electronically probes the fuel cell in the absence of hydrogen. Thus, the fuel cell is in an inactive, or passive, state throughout the testing process. The procedure is referred to as the passive state dynamic behaviour (PSDB) test. Analysis and interpretation of the passive test results is achieved by determining the circuit parameter values of an equivalent circuit model (ECM). A novel ECM of a fuel cell in a passive state is proposed, in which physical properties of the fuel cell are attributed to the circuit model components. Therefore, insight into the physical state of the fuel cell is achieved by determining the values of the circuit model parameters. A method for determining the circuit parameter values of many series connected cells (a stack) using the results from a single stack test is also presented. The PSDB test enables each cell in a fuel cell stack to be tested and analysed using a simple procedure that can be incorporated into a fuel cell system designed for backup power applications. An experimental system for implementing the PSDB test and evaluating the active performance of three different PEM fuel cells was developed. Each fuel cell exhibited the same characteristic voltage transient when subjected to the PSDB test. The proposed ECM was shown to accurately model the observed transient voltage behaviour of a single cell and many series connected cells. An example of how the PSDB test can provide information on the active functionality of a fuel cell is developed. This method consists of establishing baseline performance of the fuel cell in an active state, in conjunction with a PSDB test and identification of model parameter values. A subsequent PSDB test is used to detect changes in the state of the fuel cell that correspond to performance changes when the stack is active. An explicit example is provided, where certain cells in a stack were purposefully humidified. The change in state of the cells was identified by the PSDB test, and the performance change of the effected cells was successfully predicted. The experimental test results verify the theory presented in relation to the PSDB test and equivalent circuit model.

Proton exchange membrane fuel cell (PEMFC) is a potential alternative energy conversion device for stationary and automotive applications. Wide commercialization of PEMFC depends on progress that can be achieved to enhance its reliability and durability along with cost reduction. It is desirable to operate the PEMFC at uniform local current density and temperature distributions over the surface of the membrane electrode assembly (MEA). Non-uniform distributions of both current and temperature over the MEA could result in poor reactant and catalyst utilization as well as overall cell performance degradation. Local current distribution in the PEMFC electrodes are closely related to operating conditions, but it is also affected by the organization of the reactant flow arrangements in PEMFCs. Reactant depletion and water formation along the flow channel leads to current variation from the channel inlet to the exit, which leads to non-uniformity of local electrochemical reaction activity, and degradation of the cell performance. Flow arrangements between the anode and cathode streams, such as co-, counter- and cross- flow can exacerbate the effect of the non-uniformity considerably, producing complex current distribution patterns over the electrode surfaces. Thus, understanding of the local current density and its spatial characteristics, as well as the temperature distributions under different physical and operating conditions, is crucially important in order to develop optimum design and operational strategies. Despite the importance of the influence of the flow arrangement on the local current and temperature distributions under various operating conditions, few systematic studies have been conducted experimentally to investigate this effect. In this research, an experimental setup with special PEMFC test cells are designed and fabricated in-house, in order to conduct in-situ mapping of the local current and temperature distributions over the electrode surfaces. A segmented flow field plate and the printed circuit board (PCB) technique is used to measure the current distribution in a single PEMFC. In situ, nondestructive temperature measurements are conducted using thermocouples to determine the actual temperature distribution. Experimental studies have been conducted to investigate the effect of different flow arrangements between the anode and cathode (co-, counter-, and cross- flow) on the local current density distribution over the MEA surface. Furthermore, local current distribution has been characterized for PEMFCs under various operating conditions such as reactant stoichiometry ratios, reactant backpressure, cell temperature, cell potentials, and relative humidity for each one of the reactant flow arrangements. The dynamic characteristics of the local current in PEMFC under different operating conditions also have been studied. Temperature distributions along the parallel and serpentine flow channels in PEMFs under various operating conditions are also investigated. All independent tests are conducted to identify and optimize the key design and operational parameters for both local current and temperature distributions. It has been found that the local current density distribution is strongly affected by the flow arrangement between the anode and cathode streams and the key operating conditions. It has also been observed that the counter-flow arrangement generates the most uniform distribution for the current density, whereas the co-flow arrangement results in a considerable variation in the current density from the reactant gas stream inlet to the exit. Low stoichiometry ratio of hydrogen at the anode side has a predominant effect on the current distribution and cell performance. Further, it has been found that the dynamic characteristics and the degree of fluctuation of local current density inside PEMFC are strongly influenced by the crucial operating conditions. In-situ, nondestructive temperature measurements indicate that the temperature distribution inside the PEMFC is strongly sensitive to the cell’s current density. The temperature distribution inside the PEMFC seems to be virtually uniform at low current density, while the temperature variation increases up to 2 oC at the high current density. Finally, the present work contribution related to the local current and temperature distributions is required to understand the effect of each individual or even several operating parameters combined together on the local current and temperature distributions. This will help to develop an optimum design, which leads to enhancing the reliability and durability in operational PEMFCs.

Cette thèse réalisée dans le cadre des projets PIE CNRS AMELI-0Pt et AMEPlas et ANR AMADEUS a regroupé plusieurs entités autour de la thématique des piles à combustible : Dreux Agglomération puis l’Agence Innovation Made In Dreux (MID), le GREMI, le LACCO et initialement l’industriel MHS Equipment. L’objectif de ce travail est l’élaboration par voie plasma et l’optimisation d’électrodes de piles à combustible de type PEMFC et SAMFC dans le but d’obtenir de bonnes performances avec des charges de platine ultra faibles ou sans platine. Le projet a été organisé en quatre étapes : l’étude de la croissance simultanée de platine et de carbone co-pulvérisés par plasma, la dispersion optimale de quantités ultra faibles de catalyseur, le remplacement du platine par un alliage bimétallique à base de palladium, et le dépôt direct du catalyseur sur la membrane par plasma. En utilisant un faisceau synchrotron de rayons X (Synchrotron SOLEIL), en collaboration avec le CRMD, l’étude GISAXS des couches minces Pt-C co-pulvérisés a révélé l’organisation particulière du platine dans ce type de nanostructure. Ces couches minces Pt-C offrent d’excellentes performances (20 kW.gPt-1) avec des charges de platine ultra faibles. Des électrodes PdPt (5 %at Pt) faiblement chargées permettent d’atteindre de bonnes performances en PEMFC quasiment sans platine (12,5 kW.gPd-1 et 250 kW.gPt-1). L’étude de l’activité de catalyseurs PdAu vis-à-vis de l’oxydation du glycérol a révélé l’origine des effets synergiques du palladium et de l’or en milieu alcalin. Le dépôt plasma direct de platine associé ou non au dépôt de carbone sur membrane a été optimisé. Les performances obtenues avec des CCM (Catalyst Coated Membrane) plasma démontrent l’intérêt de ce type d’architecture. / This research work has been achieved in the context of the PIE CNRS AMELI-0Pt and AMEPlas and ANR AMADEUS projects and has gathered several entities around the Fuel Cell research: Dreux Agglomération and Agence Innovation Made In Dreux (MID), the French national research laboratories GREMI and LACCO and initially the company MHS Equipment. The project aims at developing and optimising fuel cell electrodes (anode and cathode) for PEMFC (Proton Exchange Membrane Fuel Cell) and SAMFC (Solide Alkaline Membrane Fuel Cell) entirely by plasma in order to reach effective performances with ultra low platinum loadings or none at all. The project was divided into four stages: the study of the simultaneous growth of platinum and carbon co-sputtered by plasma, the optimum dispersion of a very small amount of catalysts, the replacement of platinum by a palladium based bimetallic alloy, and the direct deposition of the catalyst on the polymer membrane by plasma sputtering. By using an X-ray synchrotron beam light source (SOLEIL Synchrotron), in collaboration with the CRMD, the GISAXS study of co-sputtered Pt-C thin films has revealed the particular organisation of platinum inside this type of nanostructure. These Pt-C thin films offer excellent performances (20 kW.cm-2) with ultra low platinum amounts. Low loaded PdPt (5 %at Pt) electrodes offered good performances almost without platinum (12,5 kW.gPd-1 et 250 kW.gPt-1). The study of the activity of PdAu catalysts (plasma sputtered) on the glycerol electro-oxidation revealed the origin of the synergistic effects of palladium and gold in an alkaline medium. The direct plasma deposition of platinum associated or not with carbon deposition on membrane has been optimised. The performances of the plasma prepared CCM (Catalyst Coated Membrane) demonstrate the potential of this type of architecture.