Le but de la thèse est de développer d’une part, une méthode permettant de quantifier la chaleur générée par la cellule de manière précise. D’autre part, il s’agit d’évaluer la performance thermique d’un panel de solutions de refroidissement pour les batteries destinées à des applications HEV/PHEV/EV. La première partie de ce rapport présente une méthode d’estimation de la chaleur globale de la cellule, permettant de prendre en compte la chaleur ohmique et la chaleur entropique. Ce modèle d’estimation de perte est couplé à un modèle thermique 2D afin d’estimer la température de la cellule. La température obtenue par simulation pour une cellule LiNi0.8Co0.15Al0.05O2/graphite 22 Ah correspond très bien aux mesures expérimentales. Dans la deuxième partie du rapport, la performance thermique de plusieurs solutions de refroidissement (refroidissement à air, refroidissement par matériau à changement de phase (MCP) et refroidissement par caloduc) pour la batterie a été évaluée expérimentalement sous plusieurs puissances de perte et plusieurs conditions de ventilation. Le refroidissement par caloduc s’est révélé d’être une solution efficace, même sous des conditions de ventilation critiques. Quant à la solution de refroidissement par MCP, le prototype qui a été expérimenté a une faible performance thermique. Cela est principalement dû à la faible conductivité thermique de la formulation MCP utilisée. Toutefois, l’utilisation d’autres formulations alternatives de MCP est envisageable. Les résultats de simulation montrent que ces formulations permettraient une amélioration significative de la performance thermique du système de refroidissement par MCP. / Lithium-ion batteries, characterized by their high energy and power density, are highly recommended as power sources for electrified vehicles (HEV/PHEV/EV). However, lithium-ion batteries are very sensitive to their environment and are prone to thermal runaway at high temperature. The goals of this thesis are to develop an accurate lithium-ion cell heat loss calculation method and to investigate the thermal performance of several cooling solutions for HEV/PHEV/EV batteries. The first part presents a global heat calculation procedure for lithium-ion cell which takes into account both the polarization heat and the entropic heat. This heat generation model was coupled with a cell two-dimensional thermal model in order to predict the cell’s temperature. Temperature estimations obtained by simulation for a 22 Ah LiNi0.8Co0.15Al0.05O2/graphite cell showed a very good agreement with experimental results. In the second part, thermal performances of several cooling solutions for HEV/PHEV/EV batteries (air, phase change material (PCM) and heat pipe) were evaluated experimentally under several heat rates and cooling conditions. Heat pipe cooling was found to be a promising cooling solution which works efficiently even under low rate ventilation cooling condition. The experimented PCM cooling system had very poor thermal performance, mainly due to the low thermal conductivity of the used PCM formulation. However, simulations showed that significant improvement could be achieved by using another alternative PCM formulation.

Foi efetuado o mapeamento da eficiência intrínseca no fotopico de dois detetores Ge(Li) do tipo falso coaxial, com fótons colimados de uma fonte de 152Eu de 1 mCi, em f unção da direção de incidência. Este mapeamento permitiu efetuar experimentalmente a correção de ângulo sólido para experimentos de correlação angular gama-gama. Esta correção não possui hipóteses como: detetor perfeitamente cilíndrico, ou com seu eixo coincidente com aquele do invólucro. A aplicação da informação de eficiência para a correção de dados de correlação angular implicou em um novo método de análise, onde é ajustada a eles uma expressão do tipo: W(?)= ?.[1+ ?_(kpar>0)??Akk .?_(m= -k)^k?C_km .e^(-1m?)]? onde os Ckm são coeficientes complexos. A qualidade do método foi verificada com a análise de correlações angulares presentes nos decaimentos dos isótopos 60Co e 100Rh com misturas multipolares conhecidas. Os resultados obtidos foram satisfatórios, demonstrando a qualidade dos métodos de mapeamento e de análise da função de correlação angular. / The scanning of the intrinsic photopeak efficiency for two Ge(Li) detectors, of false coaxial type (wrap around) was performed with collimated photons from a 152Eu source with 1 mCi, as a function of the direction of incidence. This scanning allowed to obtain experimentally the solid angle correction, to be used in gamma-gamma angular correlation experiments. This correction have no hypotheses like: detector perfectly cylindrical, or with its axis coincident with the end cup axis. The efficiency information applied for the correction of angular correlation data involved a new analysis method, where it is fitted to the data an expression Iike this W(?)= ?.[1+ ?_(kpar>0)??Akk .?_(m= -k)^k?C_km .e^(-1m?)]? the Ckm are complex coefficients. The quality of the method was checked with data analysis of angular correlation functions present in the 60Co and 100Rh decays, with known multipole mixtures. The results were satisfactory, demonstrating the quality of both methods, detector mapping and analysis of correlation functions.

A presente tese de doutorado descreve a integração de metodologias sintéticas da química de organoteluretos desenvolvidas nos últimos anos pelo grupo. Especialmente a hidroteluração de cetonas α,β-insaturadas, a resolução cinética enzimática de hidróxi-teluretos e a reação de troca Te/Li. Tais metodologias, empregadas em sequência, possibilitaram a obtenção de blocos sintéticos versáteis na preparação de reagentes organometálicos funcionalizados e enantiomericamente enriquecidos. Esse protocolo mostrou-se eficiente na preparação de uma variedade de produtos naturais, como por exemplo, feromônios de insetos-praga e butirolactonas com atividades biológicas relevantes. O trabalho foi dividido em duas partes. Estudou-se a reatividade e o emprego de organoteluretos alquílicos (sp3) e vinílicos (sp2) O-funcionalizados, na síntese dos produtos naturais citados acima. Na primeira parte do trabalho estudou-se a utilização de organoteluretos vinílicos. Esta classe de compostos foi preparada a partir da hidroteluração de alquinonas, os intermediários carbonílicos foram reduzidos com NaBH4, fornecendo uma mistura racêmica de hidróxi-teluretos vinílicos. Esses compostos foram submetidos à resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto à excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção de hidróxi-teluretos vinílicos enantiomericamente enriquecidos em até 96% e.e. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion vinílico de lítio. Pela eletronegatividade do átomo de lítio possibilitar vários tipos de transmetalações, esse intermediário é de grande valia em síntese orgânica. Na presença de eletrófilos, como CO2, esse diânion apresentou boa reatividade, gerando α-alquil-γ-butenolidas, após hidrólise em meio ácido. Tais butenolidas, constituíram-se como esqueleto avançado na síntese da (+)-Blastimicinona, (-)-Blastimicinolactol, (+)-Antimicinona, (-)-NFX-2 e todos os isômeros da Acaterina, em bons rendimentos globais. Esses compostos apresentam atividades antifúngicas, antitumorais e inibitórias de enzimas relacionadas à Arteriosclerose, respectivamente. Na segunda parte do trabalho estudou-se a utilização de um organotelureto alquílico em particular. Obtido a partir da hidroteluração da metil-vinil-cetona e redução in situ, do intermediário carbonílico. A mistura racêmica obtida foi resolvida através de resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto a excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção dos dois enantiômeros do respectivo hidróxi-telureto alquílico em excessos enantioméricos de até 99%. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion alquílico de lítio que foi transmetalado para uma série organocupratos. Ao reagi-lo com tosilatos específicos e realizar work-up com Ac2O, obteve-se uma série de feromônios de insetos-praga (C. pisi, M. destructor e D. mulleri) em bons rendimentos. / This PhD thesis describes the integration of synthetic methodologies involving organotellurides chemistry developed in recent years by the group, especially hydrotelluration of α,β-unsaturated ketones, enzymatic kinetic resolution of hydroxytellurides and Te/Li exchange reaction. These methods, used together, made it possible to obtain versatile synthetic blocks which were used in the preparation of functionalized and enantiomerically enriched organometallic reagents, featuring a synthetic key step in preparing a variety of natural products, such as Insect Pheromones and Butyrolactones with relevant biological activities. This work was divided into two parts. We studied the reactivity and the application of alkyl (sp3) and vinyl (sp2) O-functionalized organotellurides, in the synthesis of natural products cited above. In the first part of the work we studied the use of vinyl organotellurides. This class of compounds was prepared from hydrotelluration of alkynones, carbonyl intermediates were reduced with NaBH4 giving a racemic mixture of hydroxy-vinyl tellurides. These compounds were subjected to enzymatic kinetic resolution, using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good yielding hydroxy-vinylic tellurides with enantiomeric excesses up to 96%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4-(C,O) vinyl dianion. According to the characteristics of the electronegative atom of lithium, this intermediate is of great value in organic synthesis. In the presence of electrophiles such as CO2 showed good reactivity generating α-alkyl-γ-butenolides after acid hydrolysis. Such Butyrolactones constituted themselves as a skeleton for the synthesis of advanced (+)-Blastmycinone, (-)-Blastmycinolactol, (+)-Antimycinone, (-)-NFX-2 and all isomers of Acaterin in good overall yields. These compounds have antifungal and antitumor activity and inhibitory enzymes related to arteriosclerosis, respectively. In the second part of the work we studied the use of a specific alkyl organotelluride obtained by hydrotelluration of methyl vinyl ketone and in situ reduction of carbonyl intermediate by NaBH4. The racemic mixture was submitted to enzymatic kinetic resolution using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good, allowing to obtain the two enantiomers of the corresponding hydroxy-alkyl telluride with enantiomeric excess of up to 99%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4- (C,O) alkyl dianion that was used for the transmetallation for several organocuprate which when reacted with tosylates and perform specific work-up provided a number of pheromones of pest insects (C. pisi, M. destructor and D. mulleri) in good yields.

A presente tese de doutorado descreve a integração de metodologias sintéticas da química de organoteluretos desenvolvidas nos últimos anos pelo grupo. Especialmente a hidroteluração de cetonas α,β-insaturadas, a resolução cinética enzimática de hidróxi-teluretos e a reação de troca Te/Li. Tais metodologias, empregadas em sequência, possibilitaram a obtenção de blocos sintéticos versáteis na preparação de reagentes organometálicos funcionalizados e enantiomericamente enriquecidos. Esse protocolo mostrou-se eficiente na preparação de uma variedade de produtos naturais, como por exemplo, feromônios de insetos-praga e butirolactonas com atividades biológicas relevantes. O trabalho foi dividido em duas partes. Estudou-se a reatividade e o emprego de organoteluretos alquílicos (sp3) e vinílicos (sp2) O-funcionalizados, na síntese dos produtos naturais citados acima. Na primeira parte do trabalho estudou-se a utilização de organoteluretos vinílicos. Esta classe de compostos foi preparada a partir da hidroteluração de alquinonas, os intermediários carbonílicos foram reduzidos com NaBH4, fornecendo uma mistura racêmica de hidróxi-teluretos vinílicos. Esses compostos foram submetidos à resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto à excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção de hidróxi-teluretos vinílicos enantiomericamente enriquecidos em até 96% e.e. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion vinílico de lítio. Pela eletronegatividade do átomo de lítio possibilitar vários tipos de transmetalações, esse intermediário é de grande valia em síntese orgânica. Na presença de eletrófilos, como CO2, esse diânion apresentou boa reatividade, gerando α-alquil-γ-butenolidas, após hidrólise em meio ácido. Tais butenolidas, constituíram-se como esqueleto avançado na síntese da (+)-Blastimicinona, (-)-Blastimicinolactol, (+)-Antimicinona, (-)-NFX-2 e todos os isômeros da Acaterina, em bons rendimentos globais. Esses compostos apresentam atividades antifúngicas, antitumorais e inibitórias de enzimas relacionadas à Arteriosclerose, respectivamente. Na segunda parte do trabalho estudou-se a utilização de um organotelureto alquílico em particular. Obtido a partir da hidroteluração da metil-vinil-cetona e redução in situ, do intermediário carbonílico. A mistura racêmica obtida foi resolvida através de resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto a excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção dos dois enantiômeros do respectivo hidróxi-telureto alquílico em excessos enantioméricos de até 99%. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion alquílico de lítio que foi transmetalado para uma série organocupratos. Ao reagi-lo com tosilatos específicos e realizar work-up com Ac2O, obteve-se uma série de feromônios de insetos-praga (C. pisi, M. destructor e D. mulleri) em bons rendimentos. / This PhD thesis describes the integration of synthetic methodologies involving organotellurides chemistry developed in recent years by the group, especially hydrotelluration of α,β-unsaturated ketones, enzymatic kinetic resolution of hydroxytellurides and Te/Li exchange reaction. These methods, used together, made it possible to obtain versatile synthetic blocks which were used in the preparation of functionalized and enantiomerically enriched organometallic reagents, featuring a synthetic key step in preparing a variety of natural products, such as Insect Pheromones and Butyrolactones with relevant biological activities. This work was divided into two parts. We studied the reactivity and the application of alkyl (sp3) and vinyl (sp2) O-functionalized organotellurides, in the synthesis of natural products cited above. In the first part of the work we studied the use of vinyl organotellurides. This class of compounds was prepared from hydrotelluration of alkynones, carbonyl intermediates were reduced with NaBH4 giving a racemic mixture of hydroxy-vinyl tellurides. These compounds were subjected to enzymatic kinetic resolution, using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good yielding hydroxy-vinylic tellurides with enantiomeric excesses up to 96%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4-(C,O) vinyl dianion. According to the characteristics of the electronegative atom of lithium, this intermediate is of great value in organic synthesis. In the presence of electrophiles such as CO2 showed good reactivity generating α-alkyl-γ-butenolides after acid hydrolysis. Such Butyrolactones constituted themselves as a skeleton for the synthesis of advanced (+)-Blastmycinone, (-)-Blastmycinolactol, (+)-Antimycinone, (-)-NFX-2 and all isomers of Acaterin in good overall yields. These compounds have antifungal and antitumor activity and inhibitory enzymes related to arteriosclerosis, respectively. In the second part of the work we studied the use of a specific alkyl organotelluride obtained by hydrotelluration of methyl vinyl ketone and in situ reduction of carbonyl intermediate by NaBH4. The racemic mixture was submitted to enzymatic kinetic resolution using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good, allowing to obtain the two enantiomers of the corresponding hydroxy-alkyl telluride with enantiomeric excess of up to 99%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4- (C,O) alkyl dianion that was used for the transmetallation for several organocuprate which when reacted with tosylates and perform specific work-up provided a number of pheromones of pest insects (C. pisi, M. destructor and D. mulleri) in good yields.

Le procédé de soudage par friction malaxage (FSW) entraîne, d’une manière générale, une importante chute de dureté à travers le joint soudé. Dans le but de concevoir des structures aéronautiques soudées par FSW en fatigue, il est nécessaire de connaître l’impact de cette chute de dureté dans le comportement mécanique global de la soudure. Dans ces travaux, l’alliage d’aluminium à durcissement structural 2198-T8 est considéré. Une chaîne de calcul de durée de vie en fatigue d’une structure soudée par FSW est mise en place. Elle intègre un couplage de calculs et d’expériences grâce auxquels le comportement mécanique de la structure est modélisé. Dans un premier temps, le gradient de comportement mécanique de la soudure est étudié. Des essais mécaniques de traction et cycliques sont réalisés à température ambiante. La méthode de corrélation d’images numériques (DIC) est utilisée dans le but de mesurer les champs de déplacements localement dans et au voisinage du joint soudé. À partir des résultats expérimentaux, les paramètres mécaniques d’un modèle de comportement sont identifiés à partir d’un élément de volume, zone par zone à travers le joint soudé. En parallèle, une quantification des précipités durcissants T1 (Al2CuLi) est menée dans différentes zones du joint soudé à l’aide d’un Microscope Electronique en Transmission (MET). Un lien entre l’évolution de la microstructure à travers la soudure et l’évolution des paramètres mécaniques est recherché. Le modèle de comportement mécanique est utilisé sur des calculs de structure utilisant la méthode des éléments finis pour simuler le joint soudé. En parallèle, des essais de fatigue sont réalisés sur des éprouvettes uniaxiales et cruciformes soumises à des chargements uniaxiaux et multiaxiaux. À l’aide des simulations du gradient de comportement mécanique du joint soudé ainsi que des résultats mesurés en fatigue, les paramètres d’un modèle d’endommagement sont identifiés. Ce modèle est utilisé pour prédire les durées de vie en fatigue et les zones d’amorçages de fissure pour une structure soudée soumise à des chargements multiaxiaux. / The Friction Stir Welding (FSW) process generally induces a critical hardness decrease inside the welded joint. To design aeronautical structure welded by FSW in fatigue, it is then necessary to know the impact of this hardness drop on the constitutive behaviour of the junction. In this study, the hardening structural aluminium alloy 2198-T8 is considered.A fatigue lifetime assessment loop of a welded structure is implemented. It integrates a calculations and experiments coupling which is used to model the structure’s mechanical behaviour. The gradient mechanical behaviour of the weldment is initially studied.Monotonic and cyclic mechanical tests are carried out to room temperature. Digital Image Correlation (DIC) is used to measure local displacement fields around the junction. Based on this experimental data, mechanical parameters for a constitutive model are identified on a volume element, zone by zone across the welded joint. In parallel, a quantification of the T1 (Al2CuLi) strengthening precipitates is realized in different region of the joint with a Transmission Electron Microscope. A connection between the microstructure evolution and the mechanical parameters is researched. The gradient mechanical behaviour of the joint is assessed on a 3D structure by Finite Element Analysis. Furthermore, fatigue tests are carried out on uniaxial and multiaxial loadings welded specimen. Thanks to the mechanical behaviour model and the fatigue lifetime measured, a damage model is used to predict the fatigue lifetime and the crack initiation zone for a welded structure which is subjected to higher multiaxial loads.

Ce travail de thèse est centré sur l’étude de matériaux LiMPO4 (M=Fe, Mn, Co) et de leur évolution en cyclage (processus rédox et interfaces électrode / électrolyte) dans des accumulateurs Li-ion. Il a été mené essentiellement sur la base d’analyses en spectroscopie photoélectronique à rayonnement X (XPS) couplées à des tests électrochimiques. Une oxydation de surface du phosphate LiFePO4 a été mise en évidence lors d’une exposition à l’air de ce matériau avec la formation d’impuretés de surface type Fe2O3. Au plan structure électronique, l’analyse des bandes de valence des matériaux LiMPO4 (M=Fe, Mn, Co) a notamment permis, pour LiFePO4, la visualisation de l’électron spin down du niveau Fe 3d amenant la première preuve expérimentale de la configuration électronique particulière (3d↑)5(3d↓)1 de Fe2+dans ce matériau. Ce travail a également contribué à mieux comprendre l’influence de la température de fonctionnement ainsi que de la nature de l’électrode négative sur les mécanismes de vieillissement des accumulateurs Li-ion. Pour les accumulateurs LiFePO4 // Graphite, la comparaison d’interfaces solide/électrolyte distribuées spatialement a montré que le vieillissement se caractérisant par la perte de lithium actif pouvait être mis en parallèle avec une hétérogénéité de fonctionnement de l’électrode positive. Enfin, l’extension des travaux aux matériaux prometteurs d’électrode positive Li(FeMn)PO4 a révélé que le potentiel de travail de fin de charge plus élevé pour le phosphate mixte, comparativement à LiFePO4, résultait dans une réactivité accrue vis-à-vis de l’électrolyte dont les conséquences ont été analysées. / This thesis is focused on the study of LiMPO4 (M = Fe, Mn, Co) materials and on their evolution upon cycling (redox process end electrodes / electrolyte interfaces) in lithium ion cells. It is based on X-Ray Photoelectron Spectroscopy (XPS) analyses coupled with electrochemical tests. During air exposure, a surface oxidation of phosphate LiFePO4 was observed that lead to the formation of surface impurities such as Fe2O3. Concerning electronic structure, the analysis of LiMPO4 (M=Fe, Mn, Co) materials valence spectra allowed for LiFePO4 the visualization of spin down Fe 3d electron which is the first experimental proof of the particular electronic configuration (3d↑)5(3d↓)1 of Fe2+ in this material. This work also allowed a better understanding of the effect of the working temperature as well as the nature of the negative electrode on Li-ion cells ageing mechanisms. For LiFePO4 // Graphite cell, the comparison of spatially distributed solid/electrolyte interfaces showed that ageing mechanisms, characterized by a loss of active lithium, could be associated with a heterogeneity of working of the positive electrode. In addition, the extension of these studies on new promising Li(FeMn)PO4 materials for positive electrode showed that higher working potential of mixed phosphate material compared to LiFePO4 material leads to a higher electrolyte reactivity which consequences were analysed.

Les éléments capables de former un alliage avec le lithium, tels que le silicium ou l’étain constituent des composés très prometteurs en tant que matériaux d’électrodes négatives pour la prochaine génération d’accumulateurs Li-ion. Un point important réside dans la compréhension des phénomènes se produisant aux interfaces électrode/électrolyte de ces nouveaux matériaux, la stabilité de la couche de passivation (SEI) se formant lors du cyclage en surface des électrodes constituant un élément primordial vis-à-vis des performances de la batterie. A côté des processus de lithiation et delithiation du matériau actif au cours du cyclage, il est important de mieux connaître la nature, la formation et l’évolution de la SEI de même que l’évolution des oxydes natifs de surface et la réactivité chimique de l’électrode au contact de l’électrolyte. Dans ce travail de thèse, pour mieux connaître et comprendre ces différents processus, nous avons développé une approche d'analyse non destructive à différentes profondeurs de la surface de matériaux d’électrodes. Les analyses ont été réalisées par spectroscopie photoélectronique à rayonnement X (XPS), la modification d’énergie du rayonnement incident permettant une variation de la profondeur d'analyse. Cette méthodologie a été utilisée pour sonder les phénomènes aux interfaces d’électrodes à base de silicium et d’étain. Les mécanismes se produisant lors du premier cycle électrochimique puis au cours d’un long cyclage d’électrodes à base de silicium cyclées avec le sel classique LiPF6 puis avec un nouveau sel très prometteur, LiFSI ont été analysés et discutés. L’étude a été étendue à un nouveau composé intermétallique à base d’étain: MnSn2. / Compounds forming alloys with lithium, such as silicon or tin, are promising negative electrode materials for the next generation of Li-ion batteries and an important issue is to better understand the phenomena occurring at the electrode/electrolyte interfaces of these materials. The stability of the passivation layer (SEI) is crucial for good battery performance and its nature, formation and evolution have to be investigated. It is also important to follow upon cycling alloying/dealloying processes, the evolution of surface oxides with battery cycling and the change in surface chemistry when storing electrodes in the electrolyte. The aim of this thesis is to improve the knowledge of these surface reactions through a non-destructive depth-resolved photoelectron spectroscopy analysis of the surface of new negative electrodes. A unique combination utilizing hard and soft-ray photoelectron spectroscopy allows by variation of the photon energy an analysis from the extreme surface to the bulk of the particles. This experimental approach was used to access the interfacial phase transitions at the surface of silicon or tin particles as well as the composition and thickness/covering of the SEI. Interfacial mechanisms occurring upon the first electrochemical cycle and upon long-term cycling of Si-based electrodes cycled with the classical salt LiPF6 and with a new promising salt, LiFSI were investigated as well as the interfacial reactions occurring upon the first cycle of an intermetallic compound MnSn2 were studied.

Les accumulateurs lithium-ion occupent aujourd’hui une place prédominante dans le domaine du stockage de l’énergie. Leur fonctionnement et les phénomènes impliqués dans leur vieillissement sont relativement bien connus, aux températures d’utilisation proches de la température ambiante. Cependant, leur utilisation dans le cadre d’applications dites « haute température », telles que le forage pétrolier, la stérilisation « in situ » ou la géolocalisation, nécessite la levée de certains verrous techniques : la stabilité de l’électrolyte et des liants d’électrodes, la compatibilité électrolyte/séparateur, le vieillissement des matériaux et l’évolution des interfaces. Les accumulateurs sélectionnés pour ces travaux de thèse sont constitués d’un matériau lamellaire de type Li(Ni,Mn,Co)O2 pour l’électrode positive, et de graphite pour l’électrode négative. Afin de décrire les phénomènes de vieillissement associés à une telle utilisation, des analyses de surface ont été menées par Spectroscopie Photoélectronique à rayonnement X sur les électrodes issues d’accumulateurs cyclés à haute température. Ces analyses ont permis de mettre en évidence la dégradation du liant de l’électrode positive et l’évolution des interfaces électrodes/électrolyte à 85 et 120°C, et d’améliorer le choix des composants des batteries pour de meilleures performances à haute température. / Nowadays, lithium-ion batteries occupy a prominent place in the field of energy storage. Phenomena involved in their aging mechanisms are quite well known for operating temperatures close to room temperature. However, their use at high temperatures for applications such as oil drilling, "in situ" sterilization or freight tracking requires some technical issues to be improved: stability of the electrolyte and electrode binders, compatibility electrolyte / separator, aging of active materials and changes of the interfaces. The batteries selected for this thesis consist of a Li(Ni,Mn,Co)O2 lamellar material at the positive electrode and graphite at the negative electrode. To describe aging phenomena related to high temperature, surface analyzes were carried out by X-ray Photoelectron Spectroscopy on the electrodes of batteries cycled at 85 and 120°C. These analyzes reveal the degradation of the positive electrode’s binder, and the changes of electrodes/electrolyte’s interfaces at high temperature compared to ambient temperature.

En raison de leur faible pression de vapeur et de leur stabilité électrochimique (5~6 V) et thermique, les dinitriles N≡C-(CH2)n-C≡N sont proposés comme solvants d’électrolytes alternatifs aux carbonates d’alkyles habituellement utilisés dans les batteries Li-ion. L’objectif de cette thèse est d’étudier le comportement physico-chimique de ces électrolytes alternatifs (viscosité, conductivité ionique, comportement thermique, propriétés volumétriques, etc.) et leur compatibilité avec une application dans les batteries Li-ion. Deux systèmes de batteries sont étudiés en utilisant une électrode positive d’oxyde lamellaire (LiNi1/3Mn1/3Co1/3O2) associée à une électrode négative à bas potentiel (graphite) ou à plus haut potentiel (Li4Ti5O12). La cyclabilité des électrodes en demi-pile et en pile complète est étudiée en fonction de la composition de l’électrolyte et de la nature du dinitrile utilisé. Les techniques de caractérisations suivantes : spectroscopie d’impédance électrochimique, microscopie électronique et spectroscopie de photoélectrons aux rayons X, sont utilisées pour suivre le processus de passivation des électrodes par formation d’une interface solide (SEI). L’effet de la présence d’additifs favorisant la formation de la couche de passivation a été étudié et leur efficacité est ainsi clairement mise en évidence. / Due to their low vapor pressure as well as their electrochemical (5~6 V) and thermal stability, dinitriles N≡C-(CH2)n-C≡N are proposed as alternative electrolyte solvents to alkyl carbonates commonly used in Li- ion batteries. The objective of this thesis is to study the physico-chemical behavior of these alternative electrolytes (viscosity, ionic conductivity, thermal behavior, volumetric properties, etc.) and their use in Li-ion batteries. Two battery systems are studied using a lamellar oxide (LiNi1/3Mn1/3Co1/3O2) as positive electrode associated with graphite or Li4Ti5O12 as negative electrodes. The cyclability of electrodes in half-cell and full-cell is studied according to the electrolyte composition and the nature of the dinitrile used. Characterization techniques like: electrochemical impedance spectroscopy, electron microscopy and X-Ray photoelectrons spectroscopy, are used to study the passivation of the negative electrode and the stability of the positive electrode. The effect of adding specific solid electrolyte interphase (SEI) builders is investigated and their efficiency is hence clearly demonstrated.

This thesis examines the memorial meaning attributed to royal power in the Icelandic legal tradition, as it is textually negotiated in sources extant from the period c. 1250-1500. It discusses the significance and functions of the Norwegian king's legal authority as part of the Icelanders' collective remembrance of their country's legal past (spanning the years c. 870-1302), and as a defining element in the creation of the Icelandic identity as a community of law. The scope of analysis covers thirteenth- to fifteenth-century legal sources (sections of law-books and legal texts preserving legal arrangements between Iceland and Norway made in the eleventh century and in the period c. 1260-1302), and a fourteenth-century account of the Norwegian king's involvement in a settlement dispute in ninth-century Iceland. These main sources are analysed against the background of several auxiliary sources (saga narratives, diplomas) from a New Philological perspective and scrutinised using the methods developed in cultural memory studies. This provides a novel perspective on the primary sources, filling a gap in recent scholarship on cultural memory in Old Norse literature and historiography. Both categories of texts, drawing on oral and written traditions of law-making and story-telling, are vehicles for multi-faceted culturally meaningful and often contradictory memories of the Norwegian king. The Icelandic laws preserve provisions bestowed upon the Icelanders by the Norwegian monarchs, whereas the sagas convey semi-mythological images of the monarchs, who act as legislators, negotiators of legal agreements with the Icelanders, and as law-keepers. By analysing the memorial functions of royal power in the primary sources, the thesis argues for the complexity of the Icelanders' self-definition as a kingless community of law, who nevertheless incorporate and actively engage with royal power, which shapes the collective memory of the country's legal tradition.