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PhD : selection by topics

Technological challenges >> Advanced hydrogen and fuel-cells solutions for energy transition
7 proposition(s).

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Investigation of manufacturing process related structure and performance of fuel cell electrode

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Composants Pemfc

01-10-2020

SL-DRT-20-0365

arnaud.morin@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Zero emission automotive using hydrogen as a fuel and powered by a proton exchange membrane (PEM) fuel cell are now commercially available. However, large-scale commercialization of PEM fuel cell vehicles requires progress in performance, cost and durability, for which the electrode is the most limiting component. It is made of a random assembly of platinum based nanoparticles within a proton conducting polymer network. The electrode is obtained from a slurry after evaporating the solvents. Currently, research and development to improve the performance of the electrode and reduce the cost of manufacturing rely on a trial and error basis. The goal of this project is to increase the knowledge on the relationships between ink composition, electrode structure, properties and performance. The evolution of the ink during the drying process and the so obtained electrode will be characterized using neutron and X-Ray scattering, as complementary tools to unravel the organization of the catalyst material and of the polymer. By correlating these results with Operando electrochemical, structural and imaging measurements, we aim at rationalizing the design of the electrodes. This project involves partners having all the complementary skills needed for this study of most interest for the industrial partner, which is a leader in the research, development and production of fuel cell cars.

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Optimisation de l'électrode Ni-YSZ à hydrogène pour une durabilité améliorée des cellules à oxydes solides

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Production d'Hydrogène

01-10-2020

SL-DRT-20-0602

karine.couturier@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature that can directly convert fuel into electricity (fuel cell mode ? SOFC) or electricity into fuel (electrolysis mode ? SOEC). In recent years, the interest on SOCs has grown significantly thanks to their wide range of technological applications that could offer innovative solutions for the transition toward a renewable energy market. Indeed, the SOCs present various advantages, such as a good reversibility, a large fuel flexibility and a very high efficiency. Despite these advantages, the degradation in performances of SOCs is still too high to envisage the industrial deployment of this technology. Among the different degradation phenomena, the microstructural evolution of the fuel electrode, which is classically made of Nickel and Yttria stabilized Zirconia (Ni-YSZ cermet), is recognized to contribute significantly to the cell ageing. In this PhD thesis, the degradation mechanisms of the Ni-YSZ electrode will be studied. For this purpose, an integrated experimental and modelling approach will be adopted coupling (i) electrochemical testing, (ii) modeling and (iii) advanced post-test microstructural characterization. Once the mechanisms of degradation precisely understood, solutions for mitigating the degradation will be proposed via material and microstructural optimizations.

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Degradation Mechanisms of the Lanthanum Strontium Cobalt Ferrite Used as Oxygen Electrode in Solid Oxide Cells

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Production d'Hydrogène

01-10-2020

SL-DRT-20-0622

bertrand.morel@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature that can directly convert fuel into electricity (fuel cell mode ? SOFC) or electricity into fuel (electrolysis mode ? SOEC). In recent years, the interest on SOCs has grown significantly thanks to their wide range of technological applications that could offer innovative solutions for the transition toward a renewable energy market. Indeed, the SOCs present various advantages, such as a good reversibility, a large fuel flexibility and a very high efficiency. Despite these advantages, the degradation in performances is still too high to envisage the industrial deployment of this technology. Among the different degradation phenomena, the destabilization of the oxygen electrode, classically made of Lanthanum Strontium Cobalt Ferrite (LSCF), is recognized to contribute significantly to the cell ageing, especially when operated in electrolysis mode. In this context, the aim of the PhD thesis is to investigate the mechanisms controlling the electrode phase demixing and the diffusion of chemical elements. For this purpose, an experimental and modeling approach will be adopted including electrochemical testing and advanced post-test characterizations. Nano-imaging by synchrotron X-ray fluorescence and diffraction will be conducted on the aged electrodes. The acquired data will be implemented in an existing multiscale model to analyze the degradation mechanisms. Finally, recommendations in terms of materials and manufacturing conditions will proposed to improve the cell lifetime.

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Simulation of PEMFC manufacturing irregularities

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2020

SL-DRT-20-0799

pascal.schott@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

The cost of PEMFC remains the bottleneck for moving the technology to the market place. Membrane electrode assembly (MEA) manufacturing must be cost-effective and assure high quality. In-line diagnostic tools have been developed by the NREL (National Renewable Energy Laboratory), that monitor the quality of electrode coatings. They have been successfully used to detect a variety of electrode coating irregularities in R2R (Roll-to-Roll) manufactured material sets. However, limited understanding exists regarding if and to what extent electrode irregularities impact PEMFC performance and lifetime. The objective of this PhD thesis, is to improve the understanding of and predict lifetime of MEA that contain material irregularities, such as for example membrane holes or cracks, and electrode voids or thick spots. CEA's multi-physics and multi-scale modeling approach will be used, coupled with a statistical analysis of experimental data provided by or collected at NREL. The following focus areas will be addressed: ? Impact of the defects (pinholes, catalyst degradation, non uniform distribution) on performance (potential mixt) ? Impact of the defects (particle size distribution, membrane thinning) on degradation ? Probabilistic failure prediction based on sensitivity analyses of mechanistic model and experimental data The thesis will be located at CEA Grenoble France, with several 3 months missions at NREL, Colorado, USA.

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Development of an alkaline electrolyzer simulator with anion exchange polymer membrane.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2020

SL-DRT-20-0801

gserre@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Alkaline systems with anion exchange polymer membrane (AEM) are of increasing interest because they have the cumulative advantages of alkaline systems and PEM (proton exchange membrane) systems without their disadvantages: no need for platinum as a catalyst, polymer electrolyte instead of diaphragm, no need for KOH solution, no problem induced by acidity. These systems however require a significant research effort before reaching the industrial maturity. To address this theme of alkaline systems AEM, it is proposed to develop a simulator of normal and degraded operations. This tool will be the receptacle of available physicochemical models and coming ones for this technology. In practice, the lab already has a code under Matlab / Simulink for electrolyzer PEM. This code will have to be adapted to AEM electrolyzer by changing the physicochemical performance models (normal operation) and adding those for degradation. This will require analyzing the existing models in the literature and developing those that do not exist or are insufficient, using the results of experiments that will take place at the same time in a nearby laboratory. This thesis will aim at developing the code, first so that it is able to simulate the performances under different operating conditions, then that it can simulate the degradation of these performances over time according to the parameters influencing different types of degradation (membrane ...). The candidate must have skills in modeling and numerical simulation, as well as physico-chemistry and know how to interact with the people who will be doing the tests used to develop / validate new models.

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New operating strategies and PEMFC system architectures for the optimization of performances

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Système Pemfc

01-10-2020

SL-DRT-20-0820

fabrice.micoud@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Increasing both the electrochemical performances and the lifespan of Proton Exchange Membrane Fuel Cell (PEMFC) is considered as a major challenge to deploy widely this technology . This PhD proposal aims at developing, realizing and studying in details the possibilities and the improvements by the use of new operating strategies and innovative PEMFC system architectures. The gains in terms of system management, electrical power/efficiency and durability will be investigated on laboratory test Bench (controlled and ideal operation for stacks) and on real system. This PhD work shall permit : i) to deepen our understanding of degradation mechanisms and kinetics within PEMFC stack; to validate experimentally our recent innovations for hardware architecture coupled with efficient and reliable monitoring system and iii) to increase the electrochemical performance and reach the best overall efficiency.

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Understanding PEMFC small channels flooding phenomena

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Système Pemfc

01-10-2020

SL-DRT-20-0847

jean-philippe.poirot@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Proton exchange membrane fuel cells (PEMFC) are now considered as a relevant solution for the production of decarbonated electric energy, both for transport and stationary applications. Fluid management within these cells has a significant impact on their performance and durability. The flooding phenomena due to the accumulation of liquid water are detrimental to the operation of the cells, causing performance losses and long term degradation that may be irreversible. With the use of increasingly thin channels in ever more compact fuel cell stacks, these phenomena are becoming more and more frequent. The goal of this thesis is to progress in the understanding of flooding in PEMFCs. The work will consist in analyzing the link between the operating conditions, the design of the channels and the materials used in the cell. On the one hand, they will rely on many experimental results, some of which include neutron images, and secondly on multi-physics models at different scales. This will allow to couple a local approach, at the scale of a fraction of the length of a channel, and a global approach at the scale of the complete cell.

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