A obtenção de pentóxido de vanádio mesoporoso, bem como a síntese, caracterização e estudo das propriedades de novos compostos híbridos, formado a partir do xerogel de pentóxido de vanádio e do pentóxido de vanádio mesoporoso, intercalados com espécies convidadas, foram os objetivos desta tese. O interesse nestes materiais, que apresentam uma considerável gama de modificações estruturais e químicas, é devido a possibilidade de arquitetar propriedades específicas e produzir novos materiais visando aplicações em óptica, catálise, dispositivos eletrônicos e sensores. Os compostos híbridos foram obtidos mediante a reação de intercalação utilizando espécies diretivas estruturais, como cloreto de cetilpiridínio, e materiais poliméricos, como óxido de polietileno e poli o-metoxianilina, introduzidos no interior do óxido em questão. O método de síntese é simples e relativamente rápido, uma vez que os materiais são obtidos em, no máximo, 10 dias, além de não ser necessário o monitoramento durante o período de preparação e secagem. Os resultados experimentais apontaram que houve uma expansão interplanar, bem como, as propriedades eletroquímicas dos compósitos apresentaram uma maior estabilidade de após vários ciclos quando comparados ao xerogel de pentóxido de vanádio, indicando uma reação de intercalação. Uma outra etapa deste trabalho foi à obtenção de óxido de vanádio mesoporoso. A formação de mesoporos foi confirmada pelas isotermas de adsorção/desorção. Em seguida, foi realizada a reação de intercalação com a introdução de óxido de polietileno e poli o-metoxianilina. A reação de intercalação utilizando esses polímeros na matriz mesoporosa proporcionou o aumento da mobilidade de íons lítio bem como um aumento na carga total, durante a reação redox, resultando num efeito sinérgico. Neste contexto, pode-se afirmar que, o método empregado mostrou-se extremamente atrativo devido a sua simplicidade de realização, além de possibilitar a obtenção de materiais com potencial aplicação como dispositivos eletroquímicos, baterias, e sensores químicos. / Synthesis, characterization of vanadium pentoxide mesoporous and studies of properties of hybrids compound based on vanadium oxide xerogel and vanadium pentoxide mesoporous, intercalated with guest species have been the main of this thesis. The interest in those materials, that present a considerable structural and chemical modification, is due to the possibility to tailor specific properties and produce new materials to application in optic, catalysis, electronic displays and sensors. The hybrid compounds were obtained from intercalation reaction utilizing templates agent such cetylpyridinium chloride and polymerics species such polyethylene oxide and poly o-methoxyaniline into the oxide. The synthesis is simple and relatively fast, and those materials are obtained, in a maximum, 10 days, even though it is not necessary the monitoring during the preparation and dry. The experimental results show an increase of interplanar, as well as, electrochemical properties of composites presented a better stability after several cycles as compared to vanadium pentoxide xerogel, indicating an intercalation reaction. Another stage of this work was to obtain the mesoporous vanadium pentoxide. The presence of porous was confirmed by adsorption isothermal method. Afterwards, it was realized the intercalation reaction with the polyethylene oxide and poly o-methoxyaniline into the matrix. The intercalation reaction using polymers into the porous matrix resulted an increase of Li+ ions mobility as well as an increase of total charge during the redox reaction resulting a synergic effect. In this context, it can be state that, the method used showed extremely attractive due to its simple synthesis, as well as it has the possibility of obtain materials with potential application such electrochemical displays, batteries and chemical sensors.

O presente trabalho trata da preparação e da caracterização de sistemas contendo tetrassulfoftalocianinas de Co(II) (CoPcTs) e Fe(III) (FePcTs) intercaladas ou somente adsorvidas externamente em matrizes de hidróxidos duplos lamelares (HDLs). Foram sintetizados materiais com composições variadas e empregando-se diferentes métodos de síntese visando, principalmente, o isolamento de materiais com microporosidade intracristalina e/ou com um baixo grau de agregação da ftalocianina. Técnicas de caracterização textural (difração de raios-X e medidas de área superficial) e espectroscópicas (vibracional na região do infravermelho, eletrônica no UV/visível, ressonância paramagnética eletrônica e absorção de raios-X), além das análises elementar (C, H, N e metais) e termogravimétrica foram utilizadas para a caracterização dos sólidos sintetizados. Avaliaram-se os materiais como catalisadores na reação de oxidação do 2,6-di-terc-butilfenol e do catecol, utilizando O2ou H2O2 como oxidantes. Nos materiais isolados contendo a CoPcTs intercalada em HDLs com composição MgxAl (x = 2, 3 e 4) e ZnxAl (x = 4 e 5), a ftalocianina está orientada perpendicularmente às lamelas do HDL, independentemente do método de síntese e da composição dos HDLs utilizados. Adicionalmente, constatou-se que a CoPcTs intercalada está altamente agregada e que os materiais não possuem microporosidade. Porém, a diminuição da densidade de carga do HDL provoca uma pequena diminuição na agregação da CoPcTs. Sob determinada condição sintética, a CoPcTs intercalada nos HDLs ZnxAl sofre o processo de enxertia através dos grupos sulfônicos. Quando testados como catalisadores na oxidação do 2,6-di-terc-butilfenol, os materiais contendo a CoPcTs intercalada e enxertada apresentaram reatividade inexpressiva, que pode ser devida ao acesso restrito do substrato ao sítio ativo na região interlamelar. Estudos de adsorção da FePcTs em HDLs MgxAl na forma carbonato, investigados por espectroscopia eletrônica UV/Visível in situ, mostraram uma elevada tendência de agregação da ftalocianina na superfície dos HDLs. Os espectros eletrônicos indicaram também que diferentes espécies derivadas da FePcTs são formadas durante o processo de adsorção nos HDLs e que a densidade de carga influencia o tipo de espécie adsorvida: há predominância de um dímero do tipo µ-oxo nos HDLs Mg2Al e Mg3Al e do dímero (FePcTs)2 no HDL Mg4Al. Os espectros de absorção de raios-X (XANES) da FePcTs adsorvida nos HDLs MgxAl mostraram que as espécies adsorvidas apresentam geometria piramidal de base quadrada (C4v) e/ou octaédrica (Oh), corroborando com os dados de espectroscopia no UV/Visível. Já os espectros de ressonância paramagnética eletrônica mostraram que a ftalocianina de Fe(III) quando adsorvida nos HDLs gera uma mistura de espécies com configuração de baixo spin e alto spin e, também, elevada distorção rômbica. A FePcTs adsorvida nos HDLs MgxAl apresentou estabilidade e reatividade catalítica superior quando comparada com a ftalocianina livre na oxidação dos fenóis. A ftalocianina adsorvida na superfície externa do HDL deve favorecer o acesso do substrato ao sítio ativo. Uma correlação entre os estudos de adsorção e os resultados dos testes catalíticos mostrou que a espécie dimérica do tipo µ-oxo pode ser a espécie mais ativa na oxidação dos fenóis. Nestes sistemas, as camadas positivas do HDL devem provocar um enfraquecimento da ligação O-H do fenol, facilitando a sua desprotonação (uma das etapas do mecanismo de oxidação). Este último efeito pareceu atuante, pois foram observadas reatividades crescentes dos catalisadores à medida que se aumentava a densidade de carga do HDL. Estes resultados indicaram que existe um efeito cooperativo nos HDLs MgxAl contendo a FePcTs adsorvida, mostrando que o HDL não atua como um suporte inerte nos processos estudados. / The present work describes the preparation and characterization of materials containing Co(II) and Fe(III) tetrasulfonated phthalocyanines (CoPcTs and FePcTs, respectively) intercalated or adsorbed on layered double hydroxides (LDHs). Different compositions and synthetic methods were used to isolate materials with microporosity and/or the phthalocyanine in a low aggregation degree. X-ray diffraction analysis, surface area measurements, spectroscopic techniques (infrared, UV/visible and X-ray absorption), elemental analysis and thermogravimetry were used to characterize the solids. The materials were tested as catalysts in the 2,6-di-terc-butilfenol and catechol oxidation, using O2 or H2O2 as oxidants. In the materials prepared by intercalation of the CoPcTs in MgxAl (x = 2, 3 and 4) and ZnxAl (x = 4 and 5) LDHs, the phthalocyanine is perpendicularly orientated related to the LDH layers, regardless of synthetic method or LDH composition used. In addition, it was observed that the intercalated phthalocyanine is aggregated and the solids do not have microporous. However, the aggregation degree of the phthalocyanine is slightly lower when the LDH charge density decreases. Under a particular synthetic conditions the CoPcTs intercalated in the LDH ZnxAl is grafted through the sulfonic groups. Catalytic tests uisng this material in the 2,6-di-terc-butilfenol oxidation showed a neglectful reactivity, which confirms the aggregation of the intercalated CoPcTs, thus avoiding that the substrate accesses the reactive center. In an adsorption study carried by monitoring in situ the FePcTs UV/Vis electronic spectra during its addition to LDH suspensions, a strong tendency of aggregation was observed for the FePcTs. In addition, different FePcTs species are formed during the adsorption process on the LDHs, which is influenced by the LDH charge density: the µ-oxo complex is the main species adsorbed on the Mg2Al and Mg3Al LDHs, whereas for Mg4Al the non oxo-bridged dimeric complex prevailed. X-ray absorption spectra (XANES) of the adsorbed FePcTs on the MgxAl LDHs showed that the species present a square-pyramidal (C4v) and/or an octahedral (Oh) symmetry, in agreement with the UV/visible spectroscopic data. EPR spectra of these samples showed that the FePcTs adsorbed on the LDHs leads to a mixture of Fe(III) high and low spin species along with a strong rhombic distortion. The FePcTs adsorbed on the MgxAl LDHs showed an enhanced catalytic activity and longevity in the phenols oxidation compared to the homogeneous counterpart. The phthalocyanine on the LDH external surfaces allows the access of the substrate to the reactive metal center. A correlation between the adsorption study and the catalytic tests pointed that the FePcTs µ-oxo complex may be the active species in the oxidation of phenols. Furthermore, the positive charge of LDH layers may weaken the O-H bonding in the phenol molecules making them more easily ionized (one step of the phenol oxidation mechanism). This feature seems to be effective because higher activities of the catalysts were observed along with increasing charge density of the LDHs. These results indicated that a cooperative effect takes place in the materials containing the FePcTs adsorbed on the MgxAl LDHs, showing that LDH do not act as an inert support in the studied catalytic reactions.

Pour améliorer les performances des batteries au lithium, des ruptures technologiques sont nécessaires. Ceci impose que les aspects fondamentaux liés au fonctionnement de ces dispositifs électroniques soient reconsidérés. Dans cette optique, les méthodes de la chimie quantique peuvent apporter une aide précieuse, notamment pour comprendre les phénomènes électroniques microscopiques, à l'origine du stockage de l'énergie. Établir une relation directe entre la nature de la liaison chimique (microscopique) et les propriétés physico-chimiques (macroscopiques) des matériaux d'électrode pour batteries Li-Ion est donc l'objectif dans lequel s'inscrivent les travaux exposés dans cette thèse. Ce travail explore à la fois des aspects méthodologiques et des applications. Il vise à proposer des méthodologies d'analyse simples permettant de traiter les réactions électrochimiques d'un point de vue théorique et de déterminer les mécanismes microscopiques mis en jeu au cours des cycles de charge et de décharge des batteries. Les systèmes étudiés sont les composés d'insertion du graphite (Li-GICs) et un matériau hybride de type MOFs (« Metal Organic Framework ») basé sur l'ion ferrique (MIL-53(Fe)). Pour les Li-GICs, une nouvelle méthode couplant des calculs premiers principes DFT à un modèle statistique dérivé du modèle de Bethe-Peierls a été développée pour rendre compte des effets d'entropie (de configuration) dans leur diagramme de phase. Les résultats obtenus apportent un nouveau regard sur les processus électrochimiques induits par le lithium, ouvrant des perspectives technologiques intéressantes pour remédier aux problèmes de sécurité posés par ce type d'électrode. Pour le MIL-53(Fe), la méthode DFT+U a été utilisée pour rendre compte des effets de corrélation électronique et pour reproduire l'état fondamental complexe de ce système. Les résultats obtenus ont permis de comprendre l'origine de la faible capacité de ce matériau vis-`a-vis du lithium.

Les fluorures (NbF5, MoF6 et WF6) et les oxyfluorures (VOF3 et CrO2F2) de métaux de transition sont intercalés dans le graphite sous atmosphère oxydante de fluor. Ces composés (de second stade) sont utilisés en tant que précurseurs dans le but de réaliser un échange fluor-oxygène via un composé oxygéné à base de silicium: l'hexaméthyldisiloxane (HMDSO). Un mécanisme d'échange en deux étapes est proposé. Ces nouveaux matériaux présentent une réversibilité partielle vis a vis de l'intercalation électrochimique du lithium. De la même façon la réactivité des fluorures inorganiques (BF3, TiF4, NbF5, MoF6 et WF6) avec les nanotubes multiparois, élaborés par voie catalytique (Co/Al2O3), est étudié en présence de fluor. Le processus de purification suivant: traitement thermique et lavage acide est préalablement effectué. L'étude par DRX montre une intercalation partielle des nanotubes. En RPE, une modification des propriétés électroniques a pu être mise en évidence. La fluoration du [70] fullerène a une température de 320 °C, permet d'obtenir un matériau présentant une faible dispersion en composition. La liaison C-F est de type ionocovalente pour une longueur de 0,149 nm. Sa structure cristalline est cubique face centrée (cfc, a = 1,7949 nm). Les tests électrochimiques montrent, outre une défluoration de la molécule de C70, une intercalation réversible de lithium; ces deux phénomènes étant en compétition. La réduction de fluorures de graphite (covalents ou ioniques) par différentes méthodes (thermique, chimique et électrochimique) conduit à l'obtention de carbones désordonnés. Le stockage du lithium par voie électrochimique s'y effectue par l'intermédiaire de deux phénomènes situées à E < 0,2 V et à E > 0,8 V. Le premier est attribué à l'insertion du lithium entre les plans graphitiques ainsi qu'a l'adsorption de lithium dans les pores créés par le processus de réduction. A plus haut potentiel la dissociation des liaison Li-X de bord de plans conduit à une capacité supplémentaire.

In-situ polymerization is one of the most efficient methods for production of polymer clay nanocomposites. In-situ polymerization of olefins using coordination catalysts is a type of heterogeneous polymerization. In order to achieve acceptable clay nanolayer dispersion in the polyolefin matrix, the clay layer exfoliation and particle break up during the polymerization are essential requirements. A literature review on polyolefin/clay nanocomposite is given in Chapter 2. In Chapter 3, we present a new mathematical model, which is as an extension of the multigrain model (MGM), to describe the intercalative polymerization and expansion of clay interlayer spaces during polymerization using clay-supported metallocenes. The results from the model show that, under the studied conditions, mass transfer is not a strong factor controlling clay exfoliation and particle break up. If the polymerization active sites are supported uniformly on all clay surfaces, effective exfoliation will be achieved after a relative short polymerization time. In practice, obtaining good dispersion of clay nanolayers with uniform properties requires that the active sites be exclusively located on the clay nanolayer surfaces, and not extracted by the solvent to form a homogeneous solution. Factors favouring active site extraction would result in nanocomposites with poor properties. In addition, high polymerization activities, stable polymerization runs, and ease of supporting are other criteria for a successful in-situ polymerization. For this purpose we established a catalyst supporting method by which most of these requirements were met. In this method, the water content on the clay surface, which is considered as poison for the metallocene catalyst, was used to produce MAO upon reaction with trimethylaluminum (TMA). Using this method, polymerization was highly active in absence of MAO cocatalyst, knowing that MAO cocatalyst promotes active site extraction from the clay surface and results in poor powder morphology. Chapter 4 describes the development of this supporting methodology. Chapter 4 also investigates the effect of the organic modification type existing on the clay surface on the success of catalyst supporting and in-situ polymerization. We found that using the proposed supporting procedure, only tertiary ammonium type modification enhanced the in-situ polymerization, whereas the quaternary ammonium worsened the catalyst supporting efficiency and led to catalyst with poor or no polymerization activity. It is suggested that, in addition to enhancing clay surface-organic solvent compatibility (which facilitates catalyst supporting), the tertiary ammonium cation reacts with the in-situ produced MAO and increases the stability of the cocatalyst bonded to the clay surface. The effect of different polymerization conditions on the polymerization behavior and nanocomposite structural properties, such as catalyst loading during supporting, polymerization temperature and triisobutylaluminum (TIBA) concentration, were studied in Chapter 5. It was found that TIBA acts merely as scavenger. High polymerization activities were obtained with low Al/Zr ratios (Al from TIBA) and increased Al concentration decreased the polymerization activity and also the quality of powder morphology. Catalyst loading in the supporting step showed to have an important role in determining the final properties. The clay particles with higher catalyst loading resulted in better exfoliation and powder morphologies The effect of solvent type during catalyst supporting and polymerization was studied in Chapter 6. It was shown that catalyst supporting in n-hexane resulted in polymerizations with higher activities and polymers with higher molecular weight were produced. Polymerization with catalyst supported in hexane showed different ethylene uptake profiles, suggesting different mechanism of exfoliation. It is suggested that using this catalyst, the clay is mostly exfoliated before polymerization started. Similar to the original clay, the catalyst supporting efficiency on the organically modified clay was close to 100 percent. However, comparing the polymerization activities of these catalysts to those that were supported directly in the reactor just before the polymerization (in-reactor, or in-situ, supported catalysts) shows that a considerable fraction of the active sites are deactivated during the prolonged contact between catalyst and clay support surface. In Chapter 5, it was shown that the in-reactor supported catalyst had considerably higher polymerization activities, up to 40 percent of that of the homogeneous catalyst. Nanocomposites made with in-reactor supported catalysts had powder morphology and nanaolayer dispersion comparable to those made with clay-supported catalysts.

Die vorliegende Arbeit behandelt die Herstellung geordneter C60-Schichten, ihre elektrochemische Nanostrukturierung in wässrigen Lösungen und ionischen Flüssigkeiten und den Einsatz geordneter und nanostrukturierter Fullerenschichten in organischen Dünnschichttransistoren. Geordnete C60-Schichten wurden durch thermische Verdampfung im Hochvakuum hergestellt. Als Substratmaterial wurden HOPG (Graphit), Glimmer und einkristallines Silizium verwendet. Die größten einkristallinen Bereiche werden auf HOPG-Substraten erhalten. Die laterale Ausdehnung der C60-Kristallite parallel zu den Graphitstufen kann bis zu 50 µm erreichen, orthogonal zu den Stufen ist das Wachstum durch die Graphitstufen begrenzt. Die elektrochemische Reduktion von C60 -Schichten in wässriger Lösung ist elektrochemisch irreversibel. Die geflossene Ladung beträgt ein Vielfaches der theoretisch möglichen Menge. Durch die Reduktion tritt eine Nanostrukturierung der Schichtoberfläche ein, die Größe der gebildeten Cluster beträgt 20 nm bis 50 nm. Fullerenpolymere und hydriertes C60 sind die chemischen Hauptprodukte der elektrochemischen Nanostrukturierung in wässriger Lösung. Die Reduktion von Fullerenschichten in ionischen Flüssigkeiten ist aufgrund der geschlossenen Schichtoberfläche und des starken Potentialabfalls in der Fullerenschicht zunächst kinetisch gehemmt und setzt erst bei negativeren Potentialen im Bereich der Reduktion zum C60-Dianion ein. Die Reduktion der Fullerenschichten ist elektrochemisch irreversibel, zum Teil aber chemisch reversibel. Es konnte erstmals der Einsatz nanostrukturierter C60 -Schichten als aktives Halbleitermaterial in Feldeffekt-Transistoren gezeigt werden. Für die Verwendung nanostrukturierter Fullerenschichten in Feldeffekt-Transistoren wurde 11-(3-Thienyl-)undecyl-trichlorosilan als Haftvermittler eingesetzt. Die gezeigten Ergebnisse von C60 -Transistoren mit hoher Ladungsträgerbeweglichkeit und der erfolgreichen Verwendung nanostrukturierter Fullerenschichten in Transistorstrukturen zeigen die Möglichkeiten des C60 als aktives Halbleitermaterial auf.

Lorsque trois atomes de lithium sont intercales chimiquement ou électrochimiquement dans V2O5, un nouveau matériau omega-Li3V2O5 se forme irréversiblement. Il présente une structure dérivée de NaC1. La désintercalation du lithium de ce matériau est complètement réversible dans le domaine d'intercalation 0,1<=x<=3,0. Les batteries au lithium ayant la phase omega-Li3V2O5 (forme in situ) comme électrode positive présentent des performances exceptionnelles, que ce soit du point de vue de l'energie massique ou de la tenue en cyclage. Cette étude a été transposée a des matériaux dérivant de V2O5 contenant du molybdène. La formation de la phase omega a été également observée. L'ensemble de ces matériaux a été étudie du point de vue électrochimique et structural. (Diffraction X et absorption X,MET).

The search for alternate and renewable energy resources as well as the efficient use of energy and development of such systems that can help to save the energy consumption is needed because of exponential growth in world population, limited conventional fossil fuel resources, and to meet the increasing demand of clean and environment friendly substitutes. Hydrogen being the simplest, most abundant and clean energy carrier has the potential to fulfill some of these requirements provided the development of efficient, safe and durable systems for its production, storage and usage. Chemical hydrides, complex hydrides and nanomaterials, where the hydrogen is either chemically bonded to the metal ions or physiosorbed, are the possible means to overcome the difficulties associated with the storage and usage of hydrogen at favorable conditions. We have studied the structural and electronic properties of some of the chemical hydrides, complex hydrides and functionalized nanostructures to understand the kinetics and thermodynamics of these materials. Another active field relating to energy storage is rechargeable batteries. We have studied the detailed crystal and electronic structures of Li and Mg based cathode materials and calculated the average intercalation voltage of the corresponding batteries. We found that transition metal doped MgH2 nanocluster is a material to use efficiently not only in batteries but also in fuel-cell technologies. MAX phases can be used to develop the systems to save the energy consumption. We have chosen one compound from each of all known types of MAX phases and analyzed the structural, electronic, and mechanical properties using the hybrid functional. We suggest that the proper treatment of correlation effects is important for the correct description of Cr2AlC and Cr2GeC by the good choice of Hubbard 'U' in DFT+U method. Hydrogen is fascinating to physicists due to predicted possibility of metallization and high temperature superconductivity. On the basis of our ab initio molecular dynamics studies, we propose that the recent claim of conductive hydrogen by experiments might be explained by the diffusion of hydrogen at relevant pressure and temperature. In this thesis we also present the studies of phase change memory materials, oxides and amorphization of oxide materials, spintronics and sulfide materials.

In-situ polymerization is one of the most efficient methods for production of polymer clay nanocomposites. In-situ polymerization of olefins using coordination catalysts is a type of heterogeneous polymerization. In order to achieve acceptable clay nanolayer dispersion in the polyolefin matrix, the clay layer exfoliation and particle break up during the polymerization are essential requirements. A literature review on polyolefin/clay nanocomposite is given in Chapter 2. In Chapter 3, we present a new mathematical model, which is as an extension of the multigrain model (MGM), to describe the intercalative polymerization and expansion of clay interlayer spaces during polymerization using clay-supported metallocenes. The results from the model show that, under the studied conditions, mass transfer is not a strong factor controlling clay exfoliation and particle break up. If the polymerization active sites are supported uniformly on all clay surfaces, effective exfoliation will be achieved after a relative short polymerization time. In practice, obtaining good dispersion of clay nanolayers with uniform properties requires that the active sites be exclusively located on the clay nanolayer surfaces, and not extracted by the solvent to form a homogeneous solution. Factors favouring active site extraction would result in nanocomposites with poor properties. In addition, high polymerization activities, stable polymerization runs, and ease of supporting are other criteria for a successful in-situ polymerization. For this purpose we established a catalyst supporting method by which most of these requirements were met. In this method, the water content on the clay surface, which is considered as poison for the metallocene catalyst, was used to produce MAO upon reaction with trimethylaluminum (TMA). Using this method, polymerization was highly active in absence of MAO cocatalyst, knowing that MAO cocatalyst promotes active site extraction from the clay surface and results in poor powder morphology. Chapter 4 describes the development of this supporting methodology. Chapter 4 also investigates the effect of the organic modification type existing on the clay surface on the success of catalyst supporting and in-situ polymerization. We found that using the proposed supporting procedure, only tertiary ammonium type modification enhanced the in-situ polymerization, whereas the quaternary ammonium worsened the catalyst supporting efficiency and led to catalyst with poor or no polymerization activity. It is suggested that, in addition to enhancing clay surface-organic solvent compatibility (which facilitates catalyst supporting), the tertiary ammonium cation reacts with the in-situ produced MAO and increases the stability of the cocatalyst bonded to the clay surface. The effect of different polymerization conditions on the polymerization behavior and nanocomposite structural properties, such as catalyst loading during supporting, polymerization temperature and triisobutylaluminum (TIBA) concentration, were studied in Chapter 5. It was found that TIBA acts merely as scavenger. High polymerization activities were obtained with low Al/Zr ratios (Al from TIBA) and increased Al concentration decreased the polymerization activity and also the quality of powder morphology. Catalyst loading in the supporting step showed to have an important role in determining the final properties. The clay particles with higher catalyst loading resulted in better exfoliation and powder morphologies The effect of solvent type during catalyst supporting and polymerization was studied in Chapter 6. It was shown that catalyst supporting in n-hexane resulted in polymerizations with higher activities and polymers with higher molecular weight were produced. Polymerization with catalyst supported in hexane showed different ethylene uptake profiles, suggesting different mechanism of exfoliation. It is suggested that using this catalyst, the clay is mostly exfoliated before polymerization started. Similar to the original clay, the catalyst supporting efficiency on the organically modified clay was close to 100 percent. However, comparing the polymerization activities of these catalysts to those that were supported directly in the reactor just before the polymerization (in-reactor, or in-situ, supported catalysts) shows that a considerable fraction of the active sites are deactivated during the prolonged contact between catalyst and clay support surface. In Chapter 5, it was shown that the in-reactor supported catalyst had considerably higher polymerization activities, up to 40 percent of that of the homogeneous catalyst. Nanocomposites made with in-reactor supported catalysts had powder morphology and nanaolayer dispersion comparable to those made with clay-supported catalysts.

Die vorliegende Arbeit liefert einen Beitrag zum Verständnis der elektrochemischen Prozesse an der Elektrodengrenzfläche und im Festkörper graphitischer Anoden für Lithium-Ionen-Batterien. Der Zusammenhang zwischen den intrinsischen Eigenschaften des Aktivmaterials und den resultierenden Eigenschaften von Kompositelektroden stand dabei im Fokus der Untersuchungen. Die Temperaturabhängigkeit von Materialeigenschaften (Diffusionskoeffizient, Austauschstromdichte) und Elektrodeneigenschaften (Verhalten unter Strombelastung) wurde in einem Bereich von 40 °C bis -10 °C erfasst. Dazu werden elektrochemische Charakterisierungsmethoden aus der Literatur vorgestellt und hinsichtlich ihrer Gültigkeit für die Anwendung an realen Elektroden evaluiert. Die elektrochemisch aktive Oberfläche wurde bestimmt und stellte sich als ausschlaggebender Parameter für die Bewertung der Elektrodenprozesse heraus. Auf Basis korrigierter Elektrodenoberflächen konnten Austauschstromdichten für die konkurrierenden Prozesse Lithium-Interkalation und -Abscheidung ermittelt werden. Zusammen mit Kennwerten zur Keimbildungsüberspannung für Lithium-Abscheidung flossen die ermittelten Kennwerte in eine theoretische Berechnung des Zellstroms ein. Es konnte gezeigt werden, dass die Lithium-Abscheidung kinetisch deutlich gegenüber der Lithium-Interkalation bevorzugt ist, nicht nur bei niedriger Temperatur. Die Übertragbarkeit wissenschaftlicher Grundlagenexperimente auf kommerzielle Systeme war bei allen Versuchen Gegenstand der Untersuchungen. In einem separaten Beispiel einer Oberflächenmodifikation mit Zinn wurde diese Problematik besonders verdeutlicht. Zusätzlich wurde die parasitäre Abscheidung von Lithium auf graphitischen Anoden hinsichtlich der Nachweisbarkeit und Quantifizierung evaluiert. Hierfür wurde eine neue Untersuchungsmethode im Bereich der Lithium-Ionen-Batterie zur besseren Detektion von Lithium-Abscheidung und Grenzflächen-Morphologie mittels Elektronenmikroskopie entwickelt. Die Osmiumtetroxid (OsO4) Färbung ermöglichte eine deutliche Verbesserung des Materialkontrasts und erlaubte somit eine gezielte Untersuchung von graphitischen Anoden nach erfolgter Lithium-Abscheidung. Darüber hinaus konnte die selektive Reaktion des OsO4 für eine genauere Betrachtung der Solid Electrolyte Interphase genutzt werden. Eine Stabilisierung der Proben an Luft und im Elektronenstrahl konnte erreicht werden. / This work sheds light on the electrochemical processes occurring at commercially processed graphitic anodes. It raises the question whether values published in literature for mostly ideal electrode systems can be readily taken for simulation and design of real electrodes in high-energy cells. A multiple step approach is given, evaluating different methods to determine electrode and material properties independently. The electrochemically active surface area was shown to be a crucial parameter for the calculation of electrode kinetics. Using exchange current densities corrected for the electrode surface area, the overall charging current in a cell could be calculated. The resulting part of lithium deposition in the charging process is strikingly high, not only at low temperatures. To further investigate lithium deposition in terms of morphology and quantity, a method was developed for graphitic anodes. Osmium tetroxide (OsO4) staining serves well as a tool to strongly increase material contrast in electron microscopy. Thus lithium dendrites could be made visible in an unprecedented manner. Furthermore, the selective chemical reaction of osmium tetroxide allows for a better investigation of the multi-layer solid electrolyte interphase as was shown in transmission electron microscopy. Using the staining method, a stabilization of the sample under air and in the electron beam could be achieved.