Dans le but d’améliorer les performances des micro-accumulateurs au lithium, de nouvelles voies de dépôt, compatibles avec des géométries texturées, sont actuellement explorées. Au cours de ce travail de thèse, un nouvel électrolyte solide déposé par voie « humide » a été développé. Ce matériau, composé d’un liquide ionique et d’un sel de lithium confinés dans une matrice solide, a été synthétisé par polymérisation in-situ d’un oligomère diméthacrylate. Afin de définir leurs caractéristiques de conduction ionique, de nouvelles méthodes, comme le suivi de la photo-polymérisation par impédance in-situ ou encore la réalisation d’un nouveau design de cellules à base de peignes interdigités, ont été développées. De plus, le transfert du lithium a été mesuré par RMN diffusionnelle. Une diminution significative de la vitesse de diffusion des ions Li+ après la photo-polymérisation a ainsi été mise en évidence. La spectroscopie Raman a permis de démontrer que celle-ci est due à la complexation des ions par les chaines de poly(oxyde d’éthylène) de la matrice solide. En outre, grâce aux observations de différentes compositions, un mécanisme de diffusion mixte des ions Li+ par migration dans le liquide et par sauts dans le solide a été identifié. Par conséquent, ces résultats nous ont permis de définir une stratégie pour améliorer la diffusion des ions Li+ : l’ajout d’un copolymère monofonctionnel a permis de diminuer la densité de réticulation de la matrice solide et ainsi d’optimiser la mobilité des chaines polymères. En effet, les performances de cyclage dans des empilements de micro-accumulateurs complets ont été améliorées. A température ambiante, ces résultats se sont révélés très proches de ceux obtenus avec l’électrolyte solide standard LiPON. En conclusion, l’analyse établie a permis de comprendre les liens entre structure et performances électrochimiques, ce qui a permis de dégager les voies d’amélioration les plus prometteuses pour ce type d’électrolytes. / New deposition techniques compatible with making tridimensional geometries are currently being investigated with the aim of improving the performances of lithium microbatteries. This work focuses on the development of a new quasi-solid electrolyte deposited by a “wet process”. An ionic liquid-based membrane containing a lithium salt was prepared by the photo-induced polymerization of a dimethacrylate oligomer. New methods such as a new type of conductivity cell based on planar interdigitated electrodes to measure ionic conductivity as well as in-situ monitoring of photo-polymerization using impedance spectroscopy were used. Transport properties of lithium ion were measured by PGSE-NMR. Interestingly, a significant reduction of lithium ion mobility was observed after UV-curing while the total ionic conductivity only decreased slightly. This phenomenon is due to the formation of lithium ion complexes with ethylene oxide moieties of the solid matrix, evidenced by Raman spectroscopy measurements. Additionally, we have shown that the structures of the complexes depend on the salt concentration and a dual solid/liquid transport mechanism was suggested. Hence, in order to improve lithium ion diffusion, a co-polymer was added in an attempt to decrease the cross-linking density of the solid matrix thus improving its segmental motion. The cyclability of the all solid state micro batteries was indeed improved. Comparable performances with the standard solid electrolyte LiPON were obtained at room temperature. In summary, it was established that electrochemical performances of the solid state microbatteries depend to a certain extent on the structure of the polymer electrolyte. Therefore it is possible to find new ways in designing these types of electrolytes for further improvement.

No description available.

No description available.

Solid-state batteries are gaining a lot of attention in the commecial sector today. Development of the solid state electrolytes is an important part in making commercially viable solid-state batteries. While many solid-state electrolytes are struggling with low ionic conductivity, some have shown comparatively high conductivities that can be engineered to perform better to be implemented for consumer market. Silica based solid composite electrolytes (SCEs) are one of the materials that are of huge interest as solid-state electrolytes. As a continuation of the previous research into the silica based SCE’s, the current work focuses on the study of SCEs based on the commercially available mesoporous silica (MPS) of different pore sizes and nanosized silica powder (SNP). Ionic Liquid electrolyte (ILE) based on Li-TFSI and BMP-TFSI mixture was used to prepare composities under different humidity conditions. The effect of the extent of -OH group functionalization of silica, determined by FTIR on treated and untreated powders, on ionic conductivity was also evaluated. Obtained composities were evaluated with electrochemical impedance spectroscopy (EIS) and analysed with TGA to establish correlations based on particle size and pore characteristics of MPS powder. Camparison with SNP was also made in anticipation to draw correlations with MPS. It was found that the pore size and pore volume change have more impact on the conductivity compared to surafce area of commercially obtained MPS and an unexplored pheonomenon was observed in case of SNP based SCE’s. Glovebox (GB) samples at relative humidity (RH)-0.005% have higher conductivity than dryroom samples at RH-0.5%. These findings can be used for a future reference in evaluating commercial MPS based composites as solid-state electrolytes. / Solid-state-batterier får stor uppmärksamhet i den kommersiella sektorn idag. Utveckling av fasta elektrolyter är en viktig del för att göra kommersiellt gångbara solid state-batterier. Medan många fasta elektrolyter kämpar med låg jonledningsförmåga, har vissa visat jämförelsevis höga ledningsförmåga som kan konstrueras för att prestera bättre för att implementeras för konsumentmarknaden. Kiselbaserade fasta kompositelektrolyter (SCE) är ett av de material som är av stort intresse som fasta elektrolyter. Som en fortsättning på den tidigare forskningen om de kiselbaserade SCE:erna fokuserar det nuvarande arbetet på studiet av SCE:er baserade på den kommersiellt tillgängliga mesoporösa kiseldioxiden (MPS) av olika porstorlekar och nanosized kiseldioxidpulver (SNP). Jonisk flytande elektrolyt (ILE) baserad på Li-TFSI och BMP-TFSI-blandning användes för att framställa kompositer under olika luftfuktighetsförhållanden. Effekten av omfattningen av -OH-gruppfunktionalisering av kiseldioxid, bestämd med FTIR på behandlade och obehandlade pulver, på jonkonduktiviteten utvärderades också. Erhållna sammansättningar utvärderades med elektrokemisk impedansspektroskopi (EIS) och analyserades med TGA för att fastställa korrelationer baserat på partikelstorlek och poregenskaper hos MPS-pulver. Kamparison med SNP gjordes också i väntan på att dra korrelationer med MPS. Det visade sig att porstorleken och porvolymsförändringen har mer inverkan på konduktiviteten jämfört med ytan för kommersiellt erhållen MPS och ett outforskat fenomen observerades i fallet med SNP-baserade SCE. Handskbox (GB) prover vid relativ fuktighet (RH)-0,005 % har högre konduktivitet än torrrumsprover vid RH-0,5 %. Dessa resultat kan användas för en framtida referens vid utvärdering av kommersiella MPS-baserade kompositer som fasta elektrolyter.

Cotutelle entre l'Université de Montréal et l'Université catholique de Louvain / Les batteries aux ions lithium (BIL) sont considérées comme la technologie la plus prometteuse en matière de stockage d’énergie. Elles possèdent les plus hautes densités d’énergie connues, permettant la miniaturisation constante des appareils électroniques commercialisés. La recherche dans le domaine des BIL s’est plus récemment tournée vers leur implémentation dans les véhicules électriques, qui nécessitera de plus hautes densités d’énergie et de puissance . Une manière concrète d’augmenter la densité d’énergie d’une BIL est d’en augmenter le voltage de cellule. Pour se faire, la nouvelle génération de batteries sera composée de matériaux d’électrode positive à haut potentiel (tel que LiMn1.5Ni0.5O4 avec un potentiel de 4.7 V vs. Li+ /Li) et de lithium métallique en électrode négative. Néanmoins, l’introduction de ces matériaux d’électrode positive à haut potentiel est limitée par la stabilité électrochimique de l’électrolyte liquide conventionnel, composé d’un sel de lithium et de solvants organiques (typiquement LiPF6 + EC/DEC), qui s’oxyde autour de 4.2 V vs. Li+/Li , . L’utilisation du lithium métallique comme électrode négative est entravée par la nature liquide de l’électrolyte conventionnel, qui n’offre pas assez de résistance mécanique pour empêcher la formation de dendrites de lithium, causant à terme le court-circuit de la batterie. De tels courts-circuits présentent un risque d’incendie car les électrolytes liquides sont composés de solvants organiques inflammables à basse température, posant un sérieux problème de sécurité. Les électrolytes solides, de type céramique ou polymères, sont développés en alternative aux électrolytes liquides. Ils ne contiennent aucun solvant inflammable et sont stables à haute température. Ils constituent l’élément clé d’une nouvelle génération de batteries au lithium dite batteries au lithium tout-solide. Ces dernières sont développées pour répondre à des attentes élevées en termes de sécurité, de stabilité et de haute densité d’énergie. Les électrolytes solides doivent satisfaire un certain nombre d'exigences avant de pouvoir être commercialisés, notamment posséder une conductivité ionique élevée, une large fenêtre de stabilité électrochimique et une conductivité électronique négligeable. Ces propriétés constituent les critères les plus importants à prendre en compte pour la sélection de matériaux d’électrolytes solides. Cependant, on remarque dans la littérature que la majorité des études se concentre sur la conductivité ionique des électrolytes solides, reléguant au second plan l’exploration de leurs stabilité électrochimique et conductivité électronique. La fenêtre de stabilité électrochimique a longtemps été annoncée comme étant très large chez les électrolytes solides céramiques (au moins de 0 à 5 V vs. Li+/Li). Néanmoins, des études plus récentes tendent à démontrer que la valeur de cette fenêtre dépend grandement de la méthode électrochimique utilisée pour la mesurer, et qu’elle est de surcroit souvent surestimée. Dans ce contexte, le premier objectif de cette thèse a été de développer une méthode pertinente pour déterminer la fenêtre de stabilité des électrolytes solides avec précision. Cette méthode a été optimisée et validée sur des électrolytes solides céramiques phare comme Li1.5Al0.5Ge1.5(PO4)3, Li1.3Al0.3Ti1.7(PO4)3 et Li7La3Zr2O12. Quant à la conductivité électronique, elle est rarement étudiée dans les électrolytes solides, qui sont considérés comme isolants électroniques compte tenu de leur large bande interdite. Cela dit, de récentes études à ce sujet prouvent que malgré leur bande interdite, les électrolytes solides peuvent générer de la conductivité électronique par le biais de défauts, et que celle-ci, même faible, peut éventuellement mettre l’électrolyte en échec. Pour cette raison, le second objectif de ce projet de thèse a été d’explorer la formation de défauts dans les électrolytes solides afin de déterminer leur effet sur la génération de conductivité électronique. Pour avoir une vision d’ensemble, les premiers-principes ont été utilisés pour étudier six électrolytes solides largement utilisés notamment LiGe2(PO4)3, LiTi2(PO4)3, Li7La3Zr2O12, et Li3PS4. / Lithium-ion batteries (LIBs) are considered the most promising energy storage technology. LIBs electrode materials have the highest known energy densities, allowing the constant miniaturization of commercial electronic devices. Research in the field of LIBs has more recently turned to their implementation in electric vehicles, which will require higher energy and power densities . A concrete way to increase the energy density of LIBs is to increase the cell voltage. To do so, the new generation of batteries will be composed of high potential positive electrode materials (such as LiMn1.5Ni0.5O4 with a potential of 4.7 V vs. Li+/Li) and metallic lithium in the negative electrode. Nevertheless, the introduction of these high potential positive electrode materials is limited by the electrochemical stability of conventional liquid electrolytes, composed of a lithium salt and organic solvents (LiPF6 + EC/DEC), which gets oxidized around 4.2 V vs. Li+/Li , . The use of metallic lithium as the negative electrode is also hindered by the liquid nature of the conventional electrolyte, which does not offer enough mechanical resistance to prevent the formation of lithium dendrites, ultimately causing a short-circuit of the battery. Such short-circuits are likely to lead to thermal runaway because liquid electrolytes are composed of organic solvents that are flammable at low temperature, posing a serious safety issue. Solid electrolytes, based on ceramics or polymers, are developed as an alternative to liquid electrolytes. They contain no flammable solvents and are stable at high temperatures. They are the key element of a new generation of lithium batteries called all-solid-state lithium batteries. These are developed to meet high expectations in terms of safety, stability and high energy density. Solid electrolytes must satisfy a number of requirements before they can be commercialized, including possessing a high ionic conductivity, a wide electrochemical stability window and negligible electronic conductivity. These properties are the most important criteria to consider when selecting solid electrolyte materials. However, the majority of studies found in the literature focuses on the ionic conductivity of solid electrolytes, overshadowing the exploration of their electrochemical stability and electronic conductivity. The electrochemical stability window has long been reported to be very wide in ceramic solid electrolytes (at least from 0 to 5 V vs. Li+/Li). Nevertheless, more recent studies tend to show that the value of this window depends greatly on the electrochemical method used to measure it, and that it is often overestimated. In this context, the first objective of this thesis was to develop a relevant method to determine the stability window of solid electrolytes with precision. This method was optimized and validated on flagship ceramic solid electrolytes such as Li1.5Al0.5Ge1.5(PO4)3, Li1.3Al0.3Ti1.7(PO4)3 and Li7La3Zr2O12. As for the electronic conductivity, it is scarcely studied in solid electrolytes, which are considered as electronic insulators given their wide band gaps. That being said, more recent studies on this subject proved that despite their band gap, solid electrolytes can generate electronic conductivity through defects, and that electronic conductivity, even if it is weak, can eventually cause the failure of the electrolyte. For this reason, the second objective of this thesis project was to explore the formation of defects in solid electrolytes in order to determine their effect on the generation of electronic conductivity. To get a better overview, first-principles were used to investigate six widely used ceramic solid electrolytes, including LiGe2(PO4)3, LiTi2(PO4)3, Li7La3Zr2O12, and Li3PS4.

Die vorliegende Arbeit konzentriert sich auf die Synthese von neuartigen hohlen MoSx-Nanomaterialien mit kontrollierbarer Größe und Form durch die kolloidale Template Methode. Ihre möglichen Anwendungen in wässrigen Energiespeichersystemen, einschließlich Superkondensatoren und Li-Ionen-Batterien (LIBs), wurden untersucht. Im ersten Teil wurde eine neue Nanostruktur aus hohlen Kohlenstoff-MoS2-Kohlenstoff-nanoplättchen erfolgreich durch eine L-Cystein unterstützte hydrothermale Methode unter Verwendung von Gibbsit als Templat und Polydopamin (PDA) als Kohlenstoffvorläufer synthetisiert. Nach dem Kalzinieren und Ätzen des Gibbsit Templates wurden gleichförmige Hohlplättchen erhalten, die aus einer sandwichartigen Anordnung von teilweise graphitischem Kohlenstoff und zweidimensional geschichteten MoS2 Flocken bestehen. Die Plättchen haben eine ausgezeichnete Dispergierbarkeit und Stabilität in Wasser sowie eine gute elektrische Leitfähigkeit aufgrund des durch die Kalzinierung von Polydopaminbeschichtungen erzeugten Kohlenstoffs gezeigt. Das Material wird dann in einem symmetrischen Superkondensator mit 1 M Li2SO4 als Elektrolyt aufgebracht, der eine spezifische Kapazität von 248 F/g (0.12 F/cm2) bei einer konstanten Stromdichte von 0.1 A/g und eine ausgezeichnete elektrochemische Stabilität über 3000 Zyklen aufweist, was darauf hindeutet, dass hohle Kohlenstoff-MoS2-Kohlenstoffnanoplättchen vielversprechende Materialien als Kandidaten für Superkondensatoren sind. Im zweiten Teil wurde 21 molare LiTFSI, das sogenannte "Wasser-in-Salz" (WIS) Elektrolyt, in Superkondensatoren mit hohlen Kohlenstoffnanoplättchen als Elektrodenmaterial untersucht. Im Vergleich zu dem im ersten Teil verwendeten 1 molaren Li2SO4-Elektrolyten wurden bei dem vorliegenden WIS Elektrolyt signifikante Verbesserungen in einem breiteren und stabilen Potentialfenster festgestellt, das durch die geringere Leitfähigkeit mit dem Gegenstück leicht beeinflusst wird. Die elektrochemische Impedanzspektroskopie (EIS) wurde ausgiebig eingesetzt, um einen Einblick in die Reaktionsmechanismen der WIS-Superkondensatoren zu erhalten. Zusätzlich wurde auch der Einfluss der Temperatur auf die elektrochemische Leistung im Temperaturbereich zwischen 15 und 55 °C untersucht, was eine hervorragende spezifische Kapazität von 128 F/g bei dem optimierten Zustand von 55 °C ergab. Die EIS-Messungen deckten die Abnahme der angepassten Widerstände mit der Temperaturerhöhung und umgekehrt auf und beleuchteten direkt die Beziehung zwischen elektrochemischer Leistung und Arbeitstemperatur von Superkondensatoren für zuverlässige praktische Anwendungen. Im dritten Teil wurde MoS3, ein amorphes, kettenförmig strukturiertes Übergangsmetall Trichalcogenid, als vielversprechende Anode in "Wasser-in-Salz" Li-Ionen-Batterien (WIS-LIBs) nachgewiesen. Die in diesem Teil verwendeten hohlen MoS3-Nanosphären wurden mittels einer skalierbaren Säurefällungsmethode bei Raumtemperatur synthetisiert, wobei sphärische Polyelektrolytbürsten (SPB) als Schablonen verwendet wurden. Beim Einsatz in WIS-LIBs mit LiMn2O4 als Kathodenmaterial erreicht das präparierte MoS3 eine hohe spezifische Kapazität von 127 mAh/g bei einer Stromdichte von 0.1 A/g und eine gute Stabilität über 1000 Zyklen sowohl in Knopf- als auch in Pouch-Zellen. Der Arbeitsmechanismus von MoS3 in WIS-LIBs wurde auch durch Ex-situ-Röntgenbeugungsmessungen (XRD) untersucht. Während des Betriebs wird MoS3 während der anfänglichen Li-Ionen-Aufnahme irreversibel in Li2MoO4 umgewandelt und dann allmählich in eine stabilere und reversible LixMoOy-Phase (2≤y≤4)) entlang der Zyklen umgewandelt. Amorphes Li-defizientes Lix-mMoOy/MoOz wird bei der Delithiierung gebildet. Die Ergebnisse der vorliegenden Studie zeigen einfache Ansätze zur Synthese hohler MoSx-Nanomaterialien mit kontrollierbarer Morphologie unter Verwendung einer Template-basierten Methode, die auf die vielversprechende Leistung von MoSx für wässrige Energiespeicheranwendungen zurückzuführen sind. Die elektrochemischen Untersuchungen von hohlen MoSx-Nanomaterialien in wässrigen Elektrolyten geben Einblick in die Reaktionsmechanismen von wässrigen Energiespeichersystemen und treiben die Entwicklung von Metallsulfiden für wässrige Energiespeicheranwendungen voran. / The present thesis focuses on the synthesis of novel hollow MoSx nanomaterials with controllable size and shape through the colloidal template method. Their possible applications in aqueous energy storage systems, including supercapacitors and Li-ion batteries (LIBs), have been studied. In the first part, hollow carbon-MoS2-carbon nanoplates have been successfully synthesized through an L-cysteine-assisted hydrothermal method by using gibbsite as the template and polydopamine (PDA) as the carbon precursor. After calcination and etching of the gibbsite template, uniform hollow platelets, which are made of a sandwich-like assembly of partial graphitic carbon and two-dimensional layered MoS2 flakes, have been obtained. The platelets have shown excellent dispersibility and stability in water, and good electrical conductivity due to carbon coating generated by the calcination of polydopamine. The material is then applied in a symmetric supercapacitor using 1 M Li2SO4 as the electrolyte, which exhibits a specific capacitance of 248 F/g (0.12 F/cm2) at a constant current density of 0.1 A/g and an excellent electrochemical stability over 3000 cycles, suggesting that hollow carbon-MoS2-carbon nanoplates are promising candidate materials for supercapacitors. In the second part, 21 m LiTFSI, so-called “water-in-salt” (WIS) electrolyte, has been studied in supercapacitors with hollow carbon nanoplates as electrode materials. In comparison with 1 M Li2SO4 electrolyte used in the first part, significant improvements on a broader and stable potential window have been revealed in the present WISE, which is slightly influenced by the lower conductivity with the counterpart. The electrochemical impedance spectroscopy (EIS) has been extensively employed to provide an insight look on the formation of solid electrolyte interphase in the WIS-supercapacitors. Additionally, the effect of temperature on the electrochemical performance has also been investigated in the temperature range between 15 and 55 °C, yielding eminent specific capacitance of 128 F/g at the optimized condition of 55 °C. The EIS measurements disclosed the decrease of fitted resistances with the increase of temperature and vise versa, directly illuminating the relationship between electrochemical output and working temperature of supercapacitors for reliable practical applications. In the third part, MoS3, an amorphous chain-like structured transitional metal trichalcogenide, has been demonstrated as a promising anode in the “water-in-salt” Li-ion batteries (WIS-LIBs). Hollow MoS3 nanospheres used in this part have been synthesized via a scalable room-temperature acid precipitation method using spherical polyelectrolyte brushes (SPB) as the template. When applied in WIS-LIBs with LiMn2O4 as the cathode material, the prepared MoS3 achieves a high specific capacity of 127 mAh/g at the current density of 0.1 A/g and good stability over 1000 cycles in both coin cells and pouch cells. The working mechanism of MoS3 in WIS-LIBs has also been studied by ex-situ X-ray diffraction (XRD) measurements. During operation, MoS3 undergoes irreversible conversion to Li2MoO4 during the initial Li ion uptake, and is then gradually converted to a more stable and reversible LixMoOy (2≤y≤4)) phase along cycling. Amorphous Li-deficient Lix-mMoOy/MoOz is formed upon delithiation. The results in the present thesis demonstrate facile approaches for synthesizing hollow MoSx nanomaterials with controllable morphologies using a template-based method, which attribute to the promising performance of MoSx for aqueous energy storage applications. The electrochemical studies of hollow MoSx nanomaterials in aqueous electrolytes provide insight into the reaction mechanisms of aqueous energy storage systems and push forward the development of metal sulfides for aqueous energy storage applications.

Biological markers (i.e., biomarkers) are essential in clinical and epidemiological studies as they may provide mechanistic insights into the developmental origins of disease, as well as improve diagnostic testing and risk assessment for disease prevention. However, major challenges remain due to the lack of rapid yet selective analytical methods for high throughput screening that are also amenable to volume-restricted specimens. This thesis includes two major research themes that take advantage of capillary electrophoresis (CE) separations, including (1) the targeted analysis of urinary iodide and thiocyanate for assessment of nutritional adequacy and tobacco smoke exposures in the population, and (2) the discovery of new biomarkers in sweat specimens that may improve universal newborn screening programs for cystic fibrosis (CF) infants beyond impaired chloride transport. Chapter II examines the prevalence and risk factors associated with iodine deficiency in 24 h urine samples collected from 800 participants across four clinical sites in Canada as part of the Prospective Urban and Rural Epidemiological (PURE) study when using CE with UV detection in conjunction with sample self-stacking. Importantly, regional variations in iodine status were revealed with participants from Quebec City and Vancouver at greater risk for iodine deficiency than Hamilton and Ottawa. Overall, iodine supplement use, thyroxine prescription, urinary sodium excretion, and self-reported dairy intake were found to be protective factors against iodine deficiency. Chapter III applied a validated CE assay to measure urinary thiocyanate as a biomarker of tobacco smoke and dietary exposures in an international cohort of 1000 participants from the PURE study spanning 14 countries with varied income status, smoking habits, and diet quality. Current smokers residing in high-income countries had the highest extent of cyanide exposure indicative of greater harms from tobacco smoke compared to middle- and low-income countries after adjusting for smoking intensity and other covariates. Chapter IV introduces a rapid CE method with indirect UV detection to simultaneously measure sweat chloride and bicarbonate from presumptive CF infants’ residual sweat samples. Although bicarbonate did not provide clinical value in neonatal CF diagnosis, sweat chloride testing by CE may reduce test failure rates due to insufficient volumes from infants in a clinical setting. Lastly, Chapter V applied an untargeted strategy to characterize the sweat metabolome from presumptive CF infants when using multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). A panel of sweat metabolites were found to discriminate CF from non-CF (i.e., unaffected carriers) infants, including aspartic acid, glutamine, oxoproline, and pilocarpic acid, which also correlated with sweat chloride. The clinical utility of these sweat metabolites to prognosticate late-onset CF infants from indeterminate sweat chloride test results was also explored. In summary, this thesis contributes innovative separation methods for biomarker screening and discovery in clinical and epidemiological studies for the prevention and early treatment of human diseases that benefit from optimal nutrition. / Dissertation / Doctor of Philosophy (PhD)

Yes / The aim of this work was to investigate the feasibility of cross-linker free polyelectrolyte complex formation at the nanoscale between carrageenan (CAR) and protamine (PROT). The properties of CAR/PROT nanoparticles (NPs) were dependent on the carrageenan type: kappa (KC), iota (IC) and lambda (LC), concentration of components, addition of divalent cations, weight mixing ratio (WMR) of constituents and mode of component addition. In the case of 0.1% w/v solutions, IC-based NPs had the smallest particle sizes (100-150nm) and low polydispersity indices (0.1-0.4). A decrease in the solution concentration from 0.1% to 0.05% w/v enabled the formation of KC/PROT NPs. All carrageenans exhibited the ability to form NPs with surface charge ranging from -190 to 40mV. The inclusion of divalent cations caused an increase in the particle size and zeta potential. Infrared analysis confirmed the presence of a complex between CAR and PROT and showed that IC chains undergo structural changes when forming NPs. Colloidal stability of NPs was related to the initial surface charge of particles and was time- and pH-dependent. IC was found to be the most suitable type of CAR when forming nanoplexes with PROT.

Ce travail présente quelques contributions mathématiques et numériques à la modélisation des fluides à l'échelle nanométrique. On considère deux niveaux de modélisation. Au premier niveau,une description atomique est adoptée. On s'intéresse aux méthodes permettant de calculer la viscosité de cisaillement d'un fluide à partir de cette description microscopique. On étudie en particulier les propriétés mathématiques de la dynamique de Langevin hors d'équilibre permet-tant de calculer la viscosité. Le deuxième niveau de description se situe à l'échelle du continu et l'on considère une classe de modèles pour les électrolytes à l'équilibre incorporant d'une part la présence d'un confinement avec des parois chargées et d'autre part des effets de non-idéalité dus aux corrélations électrostatiques entre les ions et au phénomène d'exclusion stérique. Dans un premier temps, on étudie mathématiquement le problème de minimisation de l'énergie libre dans le cas où celle ci reste convexe (non-idéalité modérée). Puis, on considère le cas non convexe (forte non-idéalité) conduisant à une séparation de phase / This work presents some contributions to the mathematical and numerical modelling of fluids at nanometric scales. We are interested in two levels of modelling. The first level consists in an atomic description. We consider the problem of computing the shear viscosity of a fluid from a microscopic description. More precisely, we study the mathematical properties of the nonequilibrium Langevin dynamics allowing to compute the shear viscosity. The second level of description is a continuous description, and we consider a class of continuous models for equilibrium electrolytes, which incorporate on the one hand a confinement by charged solid objects and on the other hand non-ideality effects stemming from electrostatic correlations and steric exclusion phenomena due to the excluded volume effects. First, we perform the mathematical analysis of the case where the free energy is a convex function (mild non-ideality). Second, we consider numerically the case where the free energy is a non convex function (strong non-ideality) leading in particular to phase separation

O presente trabalho visou preparar e caracterizar eletrólitos poliméricos (EP) à base de poli(vinil butirato) (PVB) com diferentes sais de lítio (LiClO4, LiCF3SO3 e LiI/I2), com ou sem o plastificante g-butirolactona (GBL), além de viabilizar a aplicação dos mesmos em dispositivos eletrocrômicos e células solares. Observou-se, através das análises por espectroscopia de impedância eletroquímica, que o PVB é capaz de solvatar no máximo 40% de sal de lítio em massa. Foi verificado que as condutividades iônicas dessas amostras, em função do aumento da temperatura, podem ser explicadas pelo modelo Vogel-Tammann-Fulcher, e que o eletrólito PF04 (PVB com 40% de LiCF3SO3) possui o maior valor de condutividade (1,5´10-4 S/cm) com relação às outras amostras. Os espectros de infravermelho das amostras estudadas mostraram um deslocamento nos picos correspondentes às carbonilas da matriz polimérica em resposta à coordenação das mesmas com íons Li+. Os resultados da espectroscopia Raman comprovaram a presença do par redox (I3-/I-) no eletrólito com LiI/I2. Os difratogramas de raios-X do PVB evidenciaram um pico largo centrado em 20º (2q) com 800 c.p.s. de intensidade, a adição de LiI/I2 e LiCF3SO3 ao polímero reduziu as intensidades para 750 e 700 c.p.s respectivamente, ao contrário do observado com LiClO4, onde se nota que o sal não foi completamente solvatado pelo polímero. A micrografia obtida por microscopia eletrônica de varredura (SEM) do eletrólito com 23% de LiClO4 (amostra P04) mostraram evidências de aglomerados iônicos na superfície. As análises por calorimetria exploratória diferencial (DSC) mostraram que um aumento na concentração de sal adicionado ao polímero causou uma diminuição na temperatura de transição vítrea (Tg), e que os eletrólitos possuem em torno de 44% de cristalinidade. Os eletrólitos P04 e PF04 foram aplicados em janelas eletrocrômicas, apresentando uma diferença de 10,5 e 9,3% respectivamente entre os estados colorido e descolorido. O eletrólito com LiI/I2 foi aplicado em célula solar gerando uma fotocorrente máxima de 1,09 mA/cm2 e eficiência de 0,41% sob a irradiação de 100 mW/cm2. Eletrólitos géis com adição de 90% γ-butirolactona também foram aplicados em células solares, os valores de fotocorrente e eficiência foram incrementados (5,82 mA/cm2 e 2,1%, respectivamente). / The aim of the present study was to prepare and characterize polymer electrolytes (EP) based on poly(vinyl butyrate) (PVB) with different lithium salts (LiClO4, LiCF3SO3 and LiI/I2) and/or containing g-butyrolactone (GBL), and to apply them in electrochromic devices and solar cells. It was observed through electrochemical impedance spectroscopy that the PVB is able to solvate up to 40% in weight of lithium salt. It was found that the ionic conductivity of these samples, as a function of temperature, can be explained by Vogel-Tammann-Fulcher model, and the electrolyte PF04 (PVB with 40% of LiCF3SO3) had the highest conductivity value of 1,5´10-4 S/cm when compared to other samples. Infrared spectra of the samples showed a shift in the peaks corresponding to the carbonyl groups of the polymer matrix in response to their coordination with Li+ ions. The results of Raman spectroscopy confirmed the presence of the redox couple (I3-/I-) in the electrolyte with LiI/I2 (PVB04). The X-ray diffractograms of the PVB showed a broad peak centered at 20 (2q) com intensity of 800 cps. The addition of LiI/I2 and LiCF3SO3 to the polymer matrix decreased the intensities to 750 and 700 cps respectively, but not after the LiClO4 addition, which was explained by its not complete solvatation by the polymer matrix. The Scanning Electron Microscopy (SEM) pictures of electrolyte with 23% of LiClO4 (P04 sample) showed evidences of ion clusters on the surface. The analyzes via Differential Scanning Calorimetry (DSC) showed that an increase in the concentration of the salt added to the polymer matrix caused a decrease in glass transition temperature (Tg), and that electrolytes are about 44% crystalline. The electrolytes P04 and PF04 were applied to electrochromic windows (ECDs) and showed a transmittance difference of 10.5 and 9.3%, respectively between the colored and discolored states. The electrolyte with LiI/I2 was applied to dye sensitized solar cell (DSSC) generating a maximum photocurrent of 1.09 mA/cm2 and 0.41% of efficiency under irradiation of 100 mW/cm2. Gel electrolytes containing 90% of γ-butyrolactone were applied to DSSC and showed 5.82 mA/cm2 of photocurrent and 2.1% of efficiency.