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Sciences pour l'ingénieur >> Chimie physique et électrochimie
6 propositions.

Optical coding using new and nanostructured organolanthanides complexes for authentication applications

The organolanthanides macromolecules are suitable candidates for the realization of optical codes related to the implementation of anti-counterfeiting and authentication solutions applications. One of the main disadvantages is that their main excitation takes place under U.V. irradiation that are high-cost devices. This makes the cost of the globalized authentication solution higher. The first objective of this thesis is to synthetize complex organolanthanides excitable to wavelength greater than that of the UV by the design and syntheses of stable organic complexing antennas, but unique regardless of the lanthanide ion. The realization of optical codes by association of these molecules requires their association into organic or inorganic nanostructures (e.g. silica or latex shell), nanostructures that will be integrated to authentication solutions themselves (inks, glass, metals,...). Because there is a wide variety of materials to be included in, nanostructuration will allow to practice adaptative chemistry in a second step to facilitate blends and enhance their stability. The second objective of this thesis is therefore to produce and characterize stable nanostructures and coding to implement solutions for optical recognition. The results will be strongly connected to an on-going industrial development concerning special security inks for authentication and counterfeiting fight.

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Département : Département des Technologies des NanoMatériaux (LITEN) Laboratory : Laboratoire Chimie et Sécurité des Nanomatériaux Start Date : 01-09-2014 ECA Code : SL-DRT-14-0350 Contact : daniel.imbert@cea.fr

Protective deposition study on composite electrodes for Li-ion batteries

Most recently, research has been oriented toward protective deposits on electrodes to improve the cyclability of materials. The objective of the thesis is to evaluate, characterize and understand the impact of such a deposit on the electrochemical performance of positive and negative electrodes. The work also include an evaluation of the deposition process as an integral part of the manufacturing process of the electrode. The focus will be on high potential positive materials in order to inhibit harmfull reactions with the electrolyte but also on negative materials such as graphite to reduce the irreversibility associated to the SEI formation or on lithium titanate in order to limit its degassing whose origin is still unclear.

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Département : Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN) Laboratory : Conception et Prototypage des Batteries Start Date : 01-09-2014 ECA Code : SL-DRT-14-0677 Contact : nelly.martin@cea.fr

Electrodes microstructural optimisation of Solid Oxide Cells for co-electrolysis operation

Because of its great potential, hydrogen production by high temperature steam electrolysis has received an increasing national and international interest in recent years. The hydrogen produced by water electrolysis if taking advantage of sustainable energy sources would constitute an energy carrier with low carbon footprint and would allow limit greenhouse gas emission. In this frame, co-electrolysis at high temperatures of steam and carbon dioxide constitutes a promising process. Indeed, it allows valorising CO2 by producing a syngas of H2 and CO. This mixture can be further transformed by chemical processes into methane or liquid fuel for both stationary and transport applications. However, the electro active components of electrolyser, i.e. the solid oxide cells, have been optimised for the classical operation under hydrogen. Electrodes microstructures as well as cell dimensions are not adapted for the specific operation in co-electrolysis. In the thesis, it is proposed to design electrodes microstructures and cell dimensional characteristics in order to improve the cell efficiency and reliability when operated in co electrolysis. The morphological optimisation will be carried out thanks to a ?multi physic? and ?multi scale? model, already available at CEA.

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Département : Département Thermique Biomasse et Hydrogène (LITEN) Laboratory : Laboratoire des Technologies de l'Hydrogène Start Date : 01-10-2014 ECA Code : SL-DRT-14-0678 Contact : guilhem.roux@cea.fr

Electro-ionic conductive copolymers as binder for li-ion batteries electrodes

For automotive and nomad applications, the Li-ion batteries must be improved in terms of battery life and performances. Nowadays, the electrodes formulations contain a polymeric binder, electrochemically and electronically inactive but nevertheless required for the mechanical cohesion of the electrode. To optimize the functional material content in the electrodes, we need developing a new generation of binders, electronic and/or ionic conductive, while keeping its mechanical function. The objective of this PhD is to develop the synthesis of diblock or triblock copolymers, using the controlled radical polymerization (RAFT, ATRP ?). The different blocks will ensure the required functions to obtain a functional binder: electronic conduction, ionic conduction and adhesion (interparticles and metallic). ?Only? ionic conductive copolymers will be synthesized and tested as polymer electrolytes. The final objective of this PhD is to propose a demonstrator of Li-ion battery including the best of this new binder and/or the best of the polymer electrolytes.

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Département : Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN) Laboratory : Matériaux pour les Batteries Start Date : 01-09-2014 ECA Code : SL-DRT-14-0698 Contact : lionel.picard@cea.fr

Real-time diagnosis of PEMFC performance and durability using impedance spectroscopy

PEMFC are very promising converters of chemical energy into electrical energy for stationary and transport applications. For many years, LITEN works on the development of MEA, stacks and PEMFC systems. This work led to the development of fuel cells based on bipolar plates stamped in perfect adequation with the market for this technology. At the same time, the development and testing of prototypes in actual operating conditions have allowed acquire, for LITEN, an important feedback on these systems and to highlight the impact of fuel cells operating conditions on their performances and their lifetime. It seems to be interesting to monitor in real time, the evolution of different operating parameters to quickly control the command-control and avoid degradations linked with extreme operation conditions. The PhD thesis deals with development of a diagnostic tool in real time based on fuel cell electrochemical impedance. In this work, the development of an electric model based on physical phenomena will be made. This model will then be streamlined in in order to online diagnosis system implementation. In a second step, electrochemical impedance spectroscopy measurements will be performed in nominal operating conditions and in degraded conditions (humidity, pressure and stoichiometry defects). The correlation between model and impedance measurements will be analysed. Finally, the impedancemeter will be implemented on a fuel cell system in order to validate the relevance of laboratory measurements and to evaluate the advantages of the embedded real-time diagnosis hardware for the command-control of fuel cell system.

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Département : Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN) Laboratory : Laboratoire Intégration des Générateurs Electrochimiques Start Date : 01-09-2014 ECA Code : SL-DRT-14-0724 Contact : Sebastien.rosini@cea.fr

Management and electro-thermal modeling of Li-ion batteries: optimization of instantaneous and ageing performances

Electrochemical storage of the electrical energy represents a major stake in the context of the current energy transition. It supports renewables energies and the development of electrical vehicles. Lithium-ion batteries are well-suited due to their high energy density. Battery thermal and electrical management allows improving their performances and slowing their degradation and insuring their safety. Strong coupling of electrical and thermal aspects, through the understanding of their interactions, is needed This PhD thesis deals with the development of an electro-thermal model of a lithium ion battery. This model has many goals. First; it aims to predict battery performances and its temperature evolution with dynamic solicitation profiles. It aims to be used for the simulation of battery thermal management systems. The final goal of this study is to establish a methodology of dimensioning of passive cooling systems less energy-consuming compared to present systems. These works will be used as well as an input for the simulation platform of validation of energy management strategies.

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Département : Département des Technologies Solaires (LITEN) Laboratory : Laboratoire Stockage de l'Energie Start Date : 01-10-2014 ECA Code : SL-DRT-14-0935 Contact : fathia.karoui@cea.fr
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