Dissertations / Theses on the topic 'Lithium thin films'
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1
Berggren, Elin. "Diffusion of Lithium in Boron-doped Diamond Thin Films." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413090.
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In this thesis, the diffusion of lithium was studied on boron-doped diamond (BDD) as a potential anode material in lithium ion batteries (LIB). The initial interaction between deposited lithium and BDD thin films was studied using X-ray Photoelectron Spectroscopy (XPS). Diffusion is directly linked to reactions between lithium and carbon atoms in the BDD-lithium interface. By measuring binding energies of core-electrons of carbon and lithium before and after deposition, these reactions can be analyzed. Scanning Electron Microscopy (SEM) was used to study the BDD surface and the behaviour of deposited lithium. Experiments show that a chemical interaction occurs between lithium and carbon atoms in the surfacelayers of the BDD. The diffusion of lithium is discussed from spectroscopic data and suggests that surface diffusion is occurring and no proof of bulk diffusion was found. The results do not exclude bulk diffusion in later states but it was not found in the initial interaction at the interface after depositing lithium. SEM images show that lithium clusters in the nanometer range are formed on the BDD surface. The results of this study give insights in the initial diffusion behaviour of lithium at the BDD interface and possible following events are discussed.
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Slaven, Simon. "Thin film carbon for lithium ion batteries /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.Adviser: Ronald B. Goldner. Submitted to the Dept. of Electrical Engineering. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Santos-Ortiz, Reinaldo. "Thin Films As a Platform for Understanding the Conversion Mechanism of FeF2 Cathodes in Lithium-Ion Microbatteries." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804977/.
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Conversion material electrodes such as FeF2 possess the potential to deliver transformative improvements in lithium ion battery performance because they permit a reversible change of more than one Li-ion per 3d metal cation. They outperform current state of the art intercalation cathodes such as LiCoO2, which have volumetric and gravimetric energy densities that are intrinsically limited by single electron transfer. Current studies focus on composite electrodes that are formed by mixing with carbon (FeF2-C), wherein the carbon is expected to act as a binder to support the matrix and facilitate electronic conduction. These binders complicate the understanding of the electrode-electrolyte interface (SEI) passivation layer growth, of Li agglomeration, of ion and electron transport, and of the basic phase transformation processes under electrochemical cycling. This research uses thin-films as a model platform for obtaining basic understanding to the structural and chemical foundations of the phase conversion processes. Thin film cathodes are free of the binders used in nanocomposite structures and may potentially provide direct basic insight to the evolution of the SEI passivation layer, electron and ion transport, and the electrochemical behavior of true complex phases. The present work consisted of three main tasks (1) Development of optimized processes to deposit FeF2 and LiPON thin-films with the required phase purity and microstructure; (2) Understanding their electron and ion transport properties and; (3) Obtaining insight to the correlation between structure and capacity in thin-film microbatteries with FeF2 thin-film cathode and LiPON thin-film solid electrolyte. Optimized pulsed laser deposition (PLD) growth produced polycrystalline FeF2 films with excellent phase purity and P42/mnm crystallographic symmetry. A schematic band diagram was deduced using a combination of UPS, XPS and UV-Vis spectroscopies. Room temperature Hall measurements reveal that as-deposited FeF2 is n-type with an electron mobility of 0.33 cm2/V.s and a resistivity was 0.255 Ω.cm. The LiPON films were deposited by reactive sputtering in nitrogen, and the results indicate that the ionic conductivity is dependent on the amount of nitrogen incorporated into the film during processing. The highest ionic conductivity obtained was 1.431.9E-6 Scm-1 and corresponded to a chemical composition of Li1.9PO3.3N.21. FeF2/LiPON thin films microbatteries were assembled using a 2032 coin cell configuration and subjected to Galvanostatic cycling. HRTEM and EELS spectroscopy where performed across the FeF2/LiPON interface of samples cycled once 15 times in their lithiated and delithiated states to understand the relationship between microstructural evolution and capacity. The EELS measurements provided evidence of a three-phase conversion reaction over the first discharge described by FeF2 +2e-+2Li+↔Fe +LiF, and of incomplete reconversion back to FeF2 after the 1st cycle resulting in new Fe0 and LiF phases in delithiated samples. This incomplete conversion results in (a) a smaller phase fraction of FeF2 participating in the conversion process subsequently and (b) the formation of LiF which is resistive to both electron and ion transport. This results in the observed drastic drop in capacity after the1st cycle. More study to understand the reconversion reaction pathways is required to fully exploit the potential of FeF2 and other conversion materials as cathodes in Li ion batteries.
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Wei, Guang. "Lithium cobalt oxide thin films : preparation and characterization for electrochromic applications /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1991.
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Thesis (Ph.D.)--Tufts University, 1991.Submitted to the Dept. of Electrical Engineering (Electro-Optics Option). Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Nagy, Jonathan Tyler. "Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587673156665861.
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Strauß, Florian, Janek Binzen, Erwin Hüger, Paul Heitjans, and Harald Schmidt. "Thin LixSi Films Produced by Ion Beam Sputtering." Diffusion fundamentals 21 (2014) 11, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32405.
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Strŭzik, M., J. L. M. Rupp, S. Buecheler, and M. Rawlence. "Physical and Electronic Characterization of Li7La3Zr2O12 Doped Thin Films." Diffusion fundamentals 21 (2014) 10, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32403.
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Reinacher, Jochen [Verfasser]. "Thin films of lithium ion conducting garnets and their properties / Jochen Reinacher." Gießen : Universitätsbibliothek, 2014. http://d-nb.info/1068633867/34.
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Campbell, Bryce W. "Preparation and characterization of lithium thiogermanate thin films using RF magnetron sputtering." [Ames, Iowa : Iowa State University], 2006.
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Clayton, Donald. "Characterization of Lithium Aluminum Oxide Solid Electrolyte Thin Films from Aqueous Precursors." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23125.
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Low-temperature routes to solid electrolytes are important for construction of solid-state batteries, electrochromic devices, electrolyte-gated transistors, high-energy capacitors and sensors. Here we report an environmentally friendly aqueous solution route to amorphous thin films of solid lithium based electrolytes and related multi-layered structures. This route allows production of high quality films at very low temperatures, up to 600 °C lower than traditional melt quenching routes. Pinhole free films of thicknesses ranging from 13-150 nm produced by this route are extremely smooth and fully dense, with temperature dependent conductivities similar to those reported for samples made by energy intensive techniques. Processing conditions were examined by TGA-DSC; film evolution was monitored by FTIR; and, resulting films were characterized using FTIR, XPS, SEM, and XRD. These techniques indicate that water and nitrate removal is complete at low temperatures, and the films remain amorphous to 400 °C. Electrical analysis suggests the presence of ionic double layer capacitor behaviour as observed in similar metal oxide systems. Large magnitudes of ε'app are reported for two separate systems herein, surpassing values reported in the literature for similar materials produced by other synthetic methods. A two-fold increase in the breakdown strength of nanolaminate structures over their single-phase counterparts is also reported. The approach developed demonstrates a simple, inexpensive and environmentally benign deposition route for the fabrication of inorganic solid electrolyte thin-films and related nanolaminates, using LiAlPO, LiAlO, and TiO2:LiAlO as model systems.
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Möller, Alexander [Verfasser]. "Study of the mechanism of lithium insertion and depletion in lithium iron phosphate thin films / Alexander Möller." Gießen : Universitätsbibliothek, 2014. http://d-nb.info/106887449X/34.
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Stewart, Brian K. "Development of a Thin-Film Evaporative Cooling System for a High Energy Thulium Holmium: Lutetium Lithium Flouride Solid-State Laser Oscillator Crystal." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/6973.
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The feasibility and critical design parameters for the development of a thin-film evaporative cooling concept for a high energy, pulsed solid-state laser oscillator were investigated. The scope of the investigation was broad, and a multidisciplinary approach was employed. No contra-indicators for the feasibility of the proposed system were revealed.
A 1-dimensional two-fluid was developed to model the hydrodynamic flow and heat transfer assuming a constant wall heat flux. This analysis produced nominal pressure drops for the flow required, indicating nominal power will be required to transport fluid across the crystal surface.
Interfacial experiments reveal that the laser crystal material has a surface energy of approximately 30 mN/m, and is highly dispersive in nature.
Design rules to allow for the orthotropic thermal expansion of the crystal rod surrounded by a thin metal sleeve were developed to support the design of a hermetic crystal-metal seal. The results indicate that commercially pure nickel produces minimal joint stresses for large thermal excursions.
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Baumann, Annika [Verfasser]. "Lithium-ion conducting thin-films for solid-state batteries prepared by chemical solution deposition / Annika Baumann." Gießen : Universitätsbibliothek, 2019. http://d-nb.info/1185976930/34.
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Stewart, Brian K. "Development of a thin-film evaporative cooling system for a high energy thulium holmium lutetium lithium fluoride solid-state laser oscillator crystal /." Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-12032004-114711/unrestricted/stewart%5Fbrian%5Fk%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.S. Mostafa Ghiaasiaan, Committee Chair ; Sheldon M. Jeter, Committee Member ; Said I. Abdel-Khalik, Committee Member. Includes bibliographical references.
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Wang, Ying. "Enhanced Li-ion intercalation properties of vanadium oxides /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10561.
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Macaraig, Lea Cristina De Jesus. "Studies on Surface Modified Metal Oxides Nanofibers and Thin Films for Solar Energy Conversion and Storage." Kyoto University, 2013. http://hdl.handle.net/2433/180445.
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Figueroa, Cadillo Robinson. "Microestruturas em filmes finos de WO3 : aplicações em microbaterias." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277315.
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Orientador: Annete GorensteinTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Em dispositivos eletroquímicos como microbaterias ou dispositivos eletrocrômicos o catodo está presente na forma de filme fino. Com o objetivo de otimizar a performance de tais dispositivos, a pesquisa cientifica e tecnológica tem sido orientada na busca de novos materiais para o catodo. Este trabalho, contudo, propõe-se estudar a influencia da morfologia e da microestrutura do catodo no comportamento eletroquímico das microbaterias. O material escolhido foi o WO3. As amostras foram depositadas por sputtering reativo, e diversos parâmetros de deposição foram variados. Explorou-se a variação da potência durante a deposição e, trabalhou-se com o substrato inclinado, em modo estacionário ou rodante. Utilizaram-se diversas técnicas de caracterização. A técnica de Microscopia de Força Atômica (AFM) foi utilizada para analise de área da superfície, rugosidade, e tamanho de grão. A técnica de microscopia eletrônica MEV-FEG foi utilizada na analise da seção transversal dos filmes. O estudo eletroquímico por cronopotenciometria cíclica com limite de potencial permitiu a obtenção da capacidade de carga/descarga durante diversos ciclos. Foram obtidas amostras com e sem estrutura colunar; além disto, morfologias tipo hélice ou pilares foram conseguidas com rotação do substrato. A capacidade de carga depende fortemente do tipo de morfologia. Os melhores resultados foram obtidos com alta potência, para todas as estruturas
Abstract: In electrochemical devices like microbatteries or electrochromic devices, the cathode is present in thin film form. In order to optimize the performance of these devices, the scientific and technological research has been oriented in the search of new cathode materials. The aim of this work, however, is to study the influence of the cathode morphology and microstructure on the electrochemical behavior of microbatteries. WO3 was chosen as the thin film compound. The samples were deposited by reactive sputtering, and several deposition parameters were varied. The power during deposition was fixed in different values, and the samples were deposited with inclined substrates either stationary or rotating. Atomic Force Microscopy was used in order to obtain the surface area, roughness and grain size. Scanning electron microscopy was used in the analysis of the cross sections. The electrochemical study using chronopotentiometry with potential limits allowed the obtention of the charge/discharge capacity during several cycles. Depending on the deposition conditions, samples with or without columnar structures were obtained; also, helicoidal or pillar morphologies were attained with the rotation of the substrate. The charge capacity is strongly dependent on the morphology. The best results were obtained with high power, for all structures
Doutorado
Física
Doutor em Ciências
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Kenny, Leo Thomas. "Preparation and characterization of lithium cobalt oxide by chemical vapor deposition for application in thin film battery and electrochromic devices /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.Adviser: Terry E. Haas. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Son, Ji-Won. "Direct-write e-beam sub-micron domain engineering in lithium niobate thin films grown by liquid phase epitaxy /." May be available electronically:, 2004. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Poinot, Delphine. "Etude de couches minces de CuO pour électrode positive à forte capacité surfacique : Application aux microbatteries au lithium." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2011. http://tel.archives-ouvertes.fr/tel-00834384.
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La miniaturisation des appareils électroniques et la multiplication de leur fonctionnalités explique l'intérêt croissant porté aux microsources d'énergie telles que les microbatteries au lithium. Ces dernières sont principalement conçues pour une utilisation rechargeable, mais des systèmes non rechargeables peuvent également êtes envisagés pour certaines applications. Actuellement, la principale limitation de ces systèmes est leur capacité surfacique, n'excédant pas 200 µAh.cm-2. Afin d'obtenir une forte capacité surfacique, nous nous sommes intéressés à CuO, un matériau réagissant avec le lithium suivant un mécanisme de conversion, et présentant une capacité volumique théorique élevée (425 µAh .cm-2.µm-1). Des couches minces de CuO ont ainsi été préparées par pulvérisation radiofréquence à cathode magnétron sous atmosphère réactive (Ar + O2). L'influence des paramètres de dépôts (concentration d'oxygène, pression totale, température des substrats, distance cible-substrat, configuration de la cible) sur leurs propriétés chimiques, morphologiques et structurales a été étudiée. Ces dernières ont également été corrélées à leurs performances électrochimiques, obtenues avec un électrolyte liquide ou un électrolyte solide.
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Green, Sara. "Electrochromic Nickel – Tungsten Oxides : Optical, Electrochemical and Structural Characterization of Sputter-deposited Thin Films in the Whole Composition Range." Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-179764.
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This thesis investigates the electrochromic NixW1-x oxide thin film system, where 0 < x < 1. The thin films were deposited by reactive DC magnetron co-sputtering from one Ni and one W metal target. In addition, Ni oxide was deposited with water vapor added to the sputtering gas. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron-, Rutherford backscattering- and Raman spectroscopy. Possible nanostructures were studied by ellipsometry together with effective medium theory. Optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in 1 M lithium perchlorate in propylene carbonate (Li-PC). Li-PC electrolyte was used as it is being compatible with both W and Ni oxides. Few studies have previously been made on Ni oxides in Li-PC. Films with high Ni content, 0.85 < x < 1, were polycrystalline and all other films were amorphous. W-rich films, x < 0.5, consisted of a mixture of W oxide and NiWO4 -phases, and the Ni-rich samples, x > 0.5, probably consisted of hydrated Ni oxide and NiWO4 -phases. Films with 0 < x < 0.3 showed electrochromic properties similar to W oxide, and films with 0.7 < x < 1 behaved as Ni oxide. For 0.4 < x < 0.7 no optical change was seen. At the border of cathodic electrochromic and non-electrochromic behavior, i.e. x ~ 0.4, the sample behaved as an optically passive intercalation material. The transmittance change was 0.45 and 0.15 for the W-rich and Ni-rich films, respectively. Ni addition to W oxide improved the coloration efficiency. For the Ni-rich films the charge insertion/extraction and optical modulation was low and an aging effect resulted in strong bleaching of the samples. The advantage of W addition to Ni oxide was that the transparency at the bleached state was enhanced. Moreover, it was found that the hydrous character of the Ni oxide had a large impact on the electrochromic performance, both when electrochemically cycled in KOH and in the non-aqueous Li-PC.
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Nagpure, Suraj R. "SYNTHESIS OF TITANIA THIN FILMS WITH CONTROLLED MESOPORE ORIENTATION: NANOSTRUCTURE FOR ENERGY CONVERSION AND STORAGE." UKnowledge, 2016. http://uknowledge.uky.edu/cme_etds/67.
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This dissertation addresses the synthesis mechanism of mesoporous titania thin films with 2D Hexagonal Close Packed (HCP) cylindrical nanopores by an evaporation-induced self-assembly (EISA) method with Pluronic surfactants P123 and F127 as structure directing agents, and their applications in photovoltaics and lithium ion batteries. To provide orthogonal alignment of the pores, surface modification of substrates with crosslinked surfactant has been used to provide a chemically neutral surface. GISAXS studies show not only that aging at 4°C facilitates ordered mesostructure development, but also that aging at this temperature helps to provide orthogonal orientation of the cylindrical micelles which assemble into an ordered mesophase directly by a disorder-order transition. These films provide pores with 8-9 nm diameter, which is precisely the structure expected to provide short carrier diffusion length and high hole conductivity required for efficient bulk heterojunction solar cells. In addition, anatase titania is a n-type semiconductor with a band gap of +3.2 eV. Therefore, titania readily absorbs UV light with a wavelength below 387 nm. Because of this, these titania films can be used as window layers with a p-type semiconductor incorporated into the pores and at the top surface of the device to synthesize a photovoltaic cell. The pores provide opportunities to increase the surface area for contact between the two semiconductors, to align a p-type semiconductor at the junction, and to induce quantum confinement effects.
These titania films with hexagonal phase are infiltrated with a hole conducting polymer, poly(3-hexylthiophene) (P3HT), in order to create a p-n junctions for organic-inorganic hybrid solar cells, by spin coating followed by thermal annealing. This assembly is hypothesized to give better photovoltaic performance compared to disordered or bicontinuous cubic nanopore arrangements; confinement in cylindrical nanopores is expected to provide isolated, regioregular “wires” of conjugated polymers with tunable optoelectronic properties, such as improved hole conductivity over that in bicontinuous cubic structure. The kinetics of infiltration into the pores show that maximum infiltration occurs within less than one hour in these films, and give materials with improved photovoltaic performance relative to planar TiO2/P3HT assemblies. These oriented mesoporous titania films are also used to develop an inorganic solar cell by depositing CdTe at the top using the Close Spaced Sublimation (CSS) technique. A power conversion efficiency of 5.53% is measured for heterostructures built using mesoporous titania films, which is significantly enhanced relative to planar TiO2/CdTe devices and prior reports in the literature. These mesoporous titania films have a great potential in inorganic solar cell development and can potentially replace CdS window layers which are conventionally used in inorganic CdS-CdTe solar cells. The last part of the dissertation addresses layer-by-layer synthesis to increase the thickness of mesoporous titania films with vertically oriented 2D-HCP nanopores, and their use in lithium ion batteries as negative electrodes because of advantages such as good cycling stability, small volume expansion (~3%) during intercalation/extraction and high discharge voltage plateau. The high surface area and small wall thickness of these titania films provide excellent lithium ion insertion and reduced Li-ion diffusion length, resulting in stable capacities as high as 200-250 mAh/g over 200 cycles.
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Tintignac, Sophie. "Étude structurale et électrochimique de films de LiCoO2 préparés par pulvérisation cathodique : application aux microaccumulateurs tout solide." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00461688.
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Au cours de ce travail de thèse, nous avons mis au point un procédé d'élaboration reproductible de films minces de LiCoO2 par pulvérisation cathodique radio fréquence. L'étude paramétrique nous a permis de déterminer les conditions de dépôt optimales ainsi que les conditions de traitement thermique post-dépôt les plus adaptées afin d'aboutir aux meilleures propriétés électrochimiques pour ces électrodes. Une fois optimisés, les films minces ont été étudiés en électrolyte liquide et nous avons notamment évalué l'influence sur les performances électrochimiques de l'épaisseur du film, de la densité de courant employée, ainsi que des bornes de potentiel utilisées. Nous avons mis en évidence un excellent comportement des films sur une large gamme d'épaisseurs et régimes. La capacité obtenue pour un film de 3,6 µm à 10 µA.cm-2 est de 240 µAh.cm-2. Une étude par microspectrométrie Raman permet de montrer que les changements structuraux induits par les processus électrochimiques sont mineurs et limités à une élongation réversible des liaisons Co-O dans l'axe d'empilement. L'intégration d'un film de 450 nm d'épaisseur dans un microaccumulateur tout solide (LiCoO2/LiPON/Li) a confirmé les excellents résultats obtenus en électrolyte liquide avec une capacité de 25 µAh.cm-2. Là encore, le comportement du film reste inchangé pour des densités de courant élevées allant jusqu'à 800 µA.cm-2. Le cyclage du microaccumulateur à 10 µA.cm-2 a été maintenu pendant plus de 800 cycles sans perte notable de capacité. Pour la première fois on démontre que des films minces de LiCoO2 élaborés par pulvérisation cathodique et recuits à 500°C peuvent être utilisés dans un microaccumulateur au lithium tout solide avec des performances proches de la théorie
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Porthault, Hélène. "Étude de nouvelles voies de dépôt du matériau d'électrode positive LiCoO2 pour la réalisation de micro-accumulateurs 3D à haute capacité surfacique." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112185/document.
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La miniaturisation des systèmes électroniques est aujourd’hui l’un des enjeux majeurs de la recherche et demande une importante évolution des sources d’énergie. Les micro-accumulateurs tout solide sont une réponse parfaitement adaptée à ce besoin. Leur capacité est toutefois actuellement limitée à 50-200 µAh.cm-2 du fait de la difficulté d’employer des couches de matériaux actifs d’épaisseur supérieure à 5 µm. L’une des pistes pour augmenter la capacité spécifique des micro-accumulateurs est de déposer les différents matériaux sur un substrat texturé. Les techniques de dépôt sous vide classiques ne permettent pas de déposer des films conformes sur de telles surfaces, principalement à cause d’effets d’ombrage. L’objectif de ce travail de thèse a donc été de développer de nouvelles voies de dépôt pour la réalisation de micro-accumulateurs tout-solide 3D. Deux voies de dépôt chimique ont été explorées : la synthèse sol-gel et l’électrodépôt sous conditions hydrothermales. La synthèse sol-gel n’a pas permis d’aboutir à la réalisation de films denses et conformes. Cependant, elle s’est avérée très intéressante pour synthétiser des poudres de LiCoO2 rhomboédrique présentant d’importantes surfaces spécifiques, sans étape de broyage, à des températures de synthèse modérées (600-700°C). Le dépôt électrolytique en conditions hydrothermales s’est quant à lui révélé très prometteur tant pour sa vitesse de dépôt importante, jusqu’à 300 nm.mn-1, que pour sa température de synthèse basse, à partir de 125°C, sans nécessiter de recuit. Les films synthétisés présentent d’excellentes performances électrochimiques en électrolyte liquide et une conformité sur des substrats texturés supérieure à 97 %The miniaturization of electronic systems is today a main topic of research and requires an important evolution of energy sources. All solid state micro-batteries are a perfectly adapted solution for this need. However, their specific capacity is limited to 50-200 µAh.cm-2 due to the difficulty to use films of active materials thickness over than 5 µm. One of the answers to enhance micro-batteries specific capacity is to deposit materials on textured substrate. Nevertheless, classical vacuum deposition techniques are not adapted to deposit conformal thin films on such surfaces because of shadow effects. The aim of this PhD-work was to develop new synthesis routes to realize 3D all solid state micro-batteries. Two chemical synthesis routes were studied: the sol-gel method and the electrodeposition under hydrothermal conditions. The sol-gel synthesis was not efficient to realize conformal and dense films. However, this technique was very effective to obtain rhombohedra LiCoO2 powders with high specific surface, without grinding step, at moderate temperature (600-700°C). The electrodeposition under hydrothermal conditions was very promising, both for its high deposition rate (up to 300 nm.mn-1) and its low synthesis temperature (from 125°C) without any annealing. The synthesized films exhibited excellent electrochemical performances in liquid electrolyte and a conformity higher than 97 % on textured substrates
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Souza, Junior Edvaldo Alves de. "Filmes Cu-V-O para aplicações em catodos de microbaterias." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277289.
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Orientador: Annette GorensteinTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: O pentóxido de vanádio é um dos compostos de intercalação mais conhecidos na área de baterias de lítio. Dada sua estrutura lamelar, íons de lítio podem ser inseridos e extraídos de forma reversível, o que torna o pentóxido de vanádio promissor para uso como catodo. No entanto, o armadilhamento de parte dos íons de lítio a cada ciclo de carga e descarga provoca a perda gradativa da capacidade. A incorporação de íons metálicos na estrutura do V2 >O5 é uma das alternativas para melhorar seu desempenho nos ciclos de carga e descarga. Por outro lado, foi demonstrado que o óxido de cobre nanoparticulado é capaz de fornecer alta capacidade de carga em processos reversíveis de inserção e extração de íons lítio. Esta tese se propõe estudar a inserção/extração de íons de lítio em filmes finos de óxidos de cobre-vanádio objetivando sua aplicação em catodos de microbaterias. Um conjunto de amostras foi obtido iniciando-se com o pentóxido de vanádio, e através de acréscimos de cobre e decréscimos de vanádio, atingindo o óxido de cobre II. Óxidos bronzes, complexos, mistos e puros foram obtidos. As amostras foram depositadas através da técnica de sputtering. Na caracterização das amostras foram utilizadas técnicas de difração de raios-X, retroespalhamento Rutherford, emissão de fotoelétrons de raios-X, absorção de raios-X (XANES) e microscopia de força atômica. A inserção de íons de lítio foi realizada através da cronopotenciometria. Cada classe de óxidos apresentou características eletroquímicas próprias. Óxidos de cobre apresentaram uma capacidade de inserção de carga quatros vezes maior que a capacidade do pentóxido de vanádio (109 µAh/cm 2-µm). Bronzes de vanádio apresentaram maior estabilidade entre todos óxidos, e melhor capacidade, quando comparado com o V2 O5. A introdução de átomos de vanádio na matriz CuO permitiu a formação de óxidos mistos com maior estabilidade eletroquímica quando comparados à filmes CuO
Abstract: In the field of lithium batteries, vanadium pentoxide is one of the most studied intercalation compound. Due to its lamellar structure, lithium ions can be reversibly inserted and extracted, and the material is a promising candidate for use as a cathode. However, trapping of part of the lithium ions in each charge/discharge cycle causes a gradative loss of capacity. The incorporation of metallic ions in the V22O5host structure is one of the alternatives to improve its cycling behavior. On the other hand, it was recently demonstrated that nanosized copper oxide is capable of providing high charge capacity in reversible lithium insertion/extraction processes. The aim of the present work is to study the insertion/extraction of lithium ions in thin films of copper-vanadium oxides for application as cathode in microbatteries. A range of samples was produced, starting from pure vanadium pentoxide. By increasing the amounts of copper and decreasing the amount of vanadium in the film, the copper oxide II composition was attained. Different classes of oxides, such as bronzes, complex oxides, mixed oxides and the pure oxides were obtained. The samples were deposited by sputtering. The characterization was performed using X-Ray diffraction, Rutherford Backscattering spectrometry, X-Ray Photoemission Spectroscopy, X-Ray Absorption Spectroscopy (mainly XANES) and Atomic Force Microscopy. The electrochemical behavior was analyzed mainly by chronopotentiometry. Each class of oxides presented distinct electrochemical properties. Copper oxide films presented an insertion capacity four times greater than the capacity of the vanadium pentoxide films (109 µAh/cm 2-µm). Vanadium bronzes presented the best stability among all of the investigated materials, and a higher capacity in comparison to vanadium pentoxide. The insertion of vanadium atoms in the CuO structure allowed the obtention of mixed oxides films with higher electrochemical stability if compared to pure CuO films
Doutorado
Superfícies e Interfaces ; Peliculas e Filamentos
Doutor em Ciências
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Bach, Philipp Johannes [Verfasser], Martin [Gutachter] Stratmann, and Frank Uwe [Gutachter] Renner. "Lithiation and delithiation mechanisms of model anodes for lithium ion batteries using the example of Au thin films / Philipp Johannes Bach ; Gutachter: Martin Stratmann, Frank Uwe Renner." Bochum : Ruhr-Universität Bochum, 2014. http://d-nb.info/1142001296/34.
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Dorotík, David. "Deponované vrstvy na bázi olova a kobaltu pro Li-ion akumulátory." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442525.
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The diploma thesis deals with the principles of operation of lithium ion batteries and their properties when using deposited thin films. The thesis is mainly focused on the formation of thin films using the electrolytic method and subsequently testing the properties of the thin film in an electrochemical cell. The test criteria are mainly the value of the capacity of the prepared electrode and the impact of cycling on the electrode layer itself, where the deposited layer is assessed before cycling and after cycling on an SEM microscope..
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Park, Dae Hoon. "Optimisation de films minces électrochromes à base d’oxyde de nickel." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14031/document.
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Dans la perspective du développement de vitrages électrochromes « en milieu protonique », des films minces électrochromes à coloration anodique, à base d’oxyde de nickel, ont été synthétisés et caractérisés. Afin d’améliorer la durabilité des films minces à base de NiO, trois approches ont été envisagées. (i)Des films d’oxyde de nickel et d’oxyde mixte nickel/lithium, déposés par PLD (Pulsed Laser Deposition). Nous avons étudié l’influence du lithium sur les propriétés physico-chimiques (‘amorphisation..), et les caractéristiques électrochromes (électrochimique-optique) en milieu aqueux KOH 1M. (ii) Des films composites, préparés par voie chimique (solution), constitués d’une phase amorphe (en diffraction des Rayons X), de composition Ti1-xZnxO2-x?x, englobant des cristallites de NiO de ~ 5 nm de diamètre. Les courbes voltampérométriques révèlent que seule la phase NiO est électrochimiquement active, mais la phase amorphe, grâce aux lacunes anioniques neutres, ?x, renforce la tenue mécanique des films déposés sur les substrats FTO/verre. Il s’ensuit que ces films composites sont plus stables au cyclage, en milieu aqueux KOH 1M, que leurs homologues TiO2/NiO. (iii) Des films minces d’oxyde de nickel dopés par du carbone, préparés par une voie sol-gel originale, présentant une remarquable tenue en cyclage (> 25000 cycles en milieu aqueux KOH 1M), jamais observée jusqu’ici pour NiOAiming at enhancing the electrochromic properties of NiO thin films, deposited on FTO substrates, we have employed three different approaches. They deal with: 1) lithium doping of NiO, the corresponding thin film-deposition method is PLD (Pulsed Laser Deposition); 2) NiO nanoparticles embedded into zinc doped amorphous titanium oxide matrix, a solution method is used to deposit the corresponding thin films ; 3) Carbon-doped NiO thin films deposited using, a specific sol-gel method. Owing to lithium doping of NiO, we could induce film amorphization, thereby enhancing the film electrochemical-capacity. Most importantly, the adhesion between the film and the FTO substrate was improved leading to enhanced electrochemical cyclability in aqueous KOH electrolyte. We could enhance the electrochromic performances of TiO2/NiO composite thin films by doping TiO2 with Zn2+, forming to a new composite thin film Ti1-xZnxO2-x?x-NiO. Finally we have successfully stabilized the electrochromic properties (durability and optical property) of NiO thin films in aqueous KOH electrolyte, owing to the development of a specific sol-gel method leading to carbon-doped NiO nanoparticles. For the first time 25000 cycles were successfully achieved without significant decrease of the electrochromic performances
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Flamary-Mespoulie, Florian. "Synthèse et caractérisation de sulfures de métaux de transition comme matériaux d’électrode positive à forte capacité pour microbatteries au lithium." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0322/document.
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L’industrie microélectronique en perpétuelle évolution impose de nouvelles spécifications pour les futures générations de microbatteries au lithium. Pour ces dispositifs, il est désormais impératif d’améliorer la capacité volumique des matériaux actifs d’électrode positive ainsi que d’abaisser leur tension de fonction-nement aux alentours de 1,5 V. Ce travail propose d’étudier le comportement de sulfures de métaux de transition de formule MSx (M = Fe, Co, Ni, Ti ; x = 1, 2), réagissant vis-à-vis du lithium selon un mécanisme de conversion, à un potentiel adapté à l’application. Déposés sous forme de couches minces par pulvérisa-tion cathodique radiofréquence à cathode à effet magnétron, ces sulfures ont été caractérisés en termes de composition, morphologie et structure. Dans la plupart des cas, des films cristallisés avec une incorpo-ration minime d’oxygène ont été obtenus sans chauffage intentionnel des substrats. L’utilisation d’une configuration en couches minces et d’un électrolyte solide, propres aux microbatteries, permet une bonne réversibilité des réactions ainsi qu’une prévention des réactions parasites généralement observées pour ces sulfures en électrolyte liquide. Une caractérisation fine des propriétés électrochimiques de ces matériaux en microbatterie tout-solide au lithium a donc pu être réalisée, permettant de corréler la réver-sibilité des cycles d’insertion / extraction du lithium avec la nature du cation de métal de transition mais aussi avec la concentration en soufre dans l’électrodeThe overgoing evolution of the microelectronics industry implies new specifications when it comes to next generations of lithium microbatteries. It is now of utmost importance for these devices to increase the volumetric capacity of the positive electrode material and bring the working potential down to approxi-mately 1.5 V. Hence, this work is aimed at studying the behavior of transition metal sulfides, of formula MSx (M = Fe, Co, Ni ; x = 1, 2), which react towards lithium through conversion reaction mechanism at an adapted potential. Thin films of these materials, prepared via non-reactive radiofrequency magnetron sputtering were structurally, morphologically and compositionally characterized prior to their integration in microbatteries. In most cases, crystallized films were obtained without any intentional heating of the substrates. Also, very low oxygen incorporation within the deposited materials was observed. Thanks to the combined use of thin film and all-solid-state configuration in the microbatteries, good reversibility of the reactions is allowed and parasitic reactions generally observed for transition metal sulfides electrodes in conventionally used liquid electrolytes cells can be avoided. Thus, deep electrochemical characteriza-tions were successfully conducted on the microbatteries. For these materials, it was shown that the re-versibility of the lithium insertion / extraction cycles during operation is directly linked to the nature of the transition metal cation and to the overall sulfur concentration in the electrode material
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Kovalevich, Tatiana. "Tunable Bloch surface waves devices." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD022/document.
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Cette thèse est consacrée au développement de dispositifs accordables sur la base de cristaux photoniques unidimensionnels qui peuvent supporter des ondes de surface de Bloch (BSW). Tout d'abord, nous explorons les possibilités de contrôler la direction de propagation des BSW par le biais de la polarisation de la lumière incidente. Dans ce cas, nous gravons sur le dessus du cristal photonique 1D des structures passives de type réseau, qui permettent à la fois de coupler la lumière incidente aux BSWs et de se comporter comme une lame séparatrice ultracompacte contrôlée par la polarisation lumineuse. Nous avons testé ce type de coupleur sur des cristaux photoniques 1D fonctionnant dans l’air et dans l’eau. Ensuite, nous démontrons l'accordabilité des BSWs en ajoutant une fine couche active dans la structure photonique multicouche. Il s’agit d’un film mince de niobate de lithium monocristallin qui permet d’introduire des propriétés anisotropes dans le cristal photonique 1D. Différentes façons de fabriquer des cristaux photoniques 1D contenant du niobate de lithium monocristallin ont été développées dans le cadre de ce travail. Ces travaux nous ont permis d’explorer le concept de contrôle électro-optique des BSWsThis thesis is devoted to develop tunable devices on the base of one-dimensional photonic crystals (1DPhC) which can sustain Bloch surface waves (BSWs).First, we explore the possibilities to control the BSW propagation direction with polarization of incident light. In this case we manufacture additional passive structures such as gratings on the top of the 1DPhC, which are working both as a BSW launcher and polarization–controlled “wave-splitters”. We test this type of launcher in air and in water as an external medium. Then, we demonstrate the tunability of the BSW by adding an active layers into the multilayer stack. Here a crystalline X-cut thin film lithium niobate (TFLN) is used to introduce anisotropic properties to the whole 1DPhC. Different ways to manufacture 1D PhCs with LiNbO3 on the top would be described. Finally, we explore the concept of the electro-optically tuned BSW
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Dubois, Vincent. "Electrodes positives lithiées d’oxysulfures de titane pour microbatteries Li-ion." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14858/document.
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Le développement à grande échelle des microbatteries pour des applications diverses comme l’alimentation de secours de certains composants électroniques dans les téléphones portables nécessite une compatibilité avec le procédé de solder-reflow employé dans le domaine de la microélectronique. Dans ce contexte, cette étude porte sur la mise au point d’un nouveau procédé de réalisation de couches minces d’oxysulfures de titane lithiés (LixTiOySz) pour une utilisation en tant qu’électrode positive dans une microbatterie Li-ion. Tout d’abord ce travail a débuté par la synthèse et la caractérisation de plusieurs compositions de sulfures de titane lithiés à l’état massif par réaction en solution de TiS2 ou TiS3 avec le n-butyllithium mais aussi par réaction à l’état solide à haute température entre les précurseurs TiS2, Li2S et Ti. Par la suite, des couches minces de LixTiOySz ont été déposées par pulvérisation cathodique radiofréquence à effet magnétron de cibles réalisées à partir des matériaux lithiés à l’état massif. La composition chimique de ces dépôts dépend de celle de la cible utilisée ce qui permet d’obtenir des couches plus ou moins riches en lithium et en soufre. En revanche, elles sont toutes très mal cristallisées, denses et elles ne présentent pas de structuration particulière. Enfin, les caractérisations électrochimiques des dépôts de LixTiOySz, à la fois en électrolyte liquide et solide, ont permis de mettre en évidence une corrélation entre leur composition chimique et leur comportement électrochimique. Globalement, ces dernières sont performantes, compatibles avec le solder-reflow et donc tout à fait intéressante pour l’applicationLarge-scale development of microbatteries for various applications such as back-up power sources for cell phone electronic components needs suitability with reflowing process that is often used in microelectronic. Here we report on the development of a new realization process to produce lithiated titanium oxysulfides (LixTiOySz) thin films for use as positive electrode in Li-ion microbatteries. First of all, this work began with synthesis and characterization of several lithiated titanium sulfides compounds prepared by reaction between TiS2 or TiS3 with n-butyllithium but also by solid state reaction at high temperature between TiS2, Li2S and Ti. Then, LixTiOySz thin films were sputtered by magnetron effect radio-frequency sputtering from targets made of lithiated materials previously synthesized. The chemical composition of those films depends on the target one and allows obtaining thin films with different lithium and sulfur contents. In contrast, they are all amorphous, dense and they don’t have a morphological structuration. Finally, electrochemical characterizations of thin films, both in liquid and solid electrolyte, have highlighted a correlation between their chemical composition and their electrochemical behavior. Taken as a whole, LixTiOySz thin films are powerful, suitable with reflowing process and thus very interesting for the application
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Trupkovic, Alexandra. "Etude de verres borates de lithium utilisables dans les microbatteries : corrélation conductivité ionique / propriétés thermomécaniques." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00659229.
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L'utilisation croissante de systèmes électroniques miniaturisés induit une forte demande en microsources d'énergie performantes, telles que les microbatteries au lithium. En vue d'améliorer les propriétés de l'électrolyte, nous avons étudié les propriétés électriques et thermomécaniques d'électrolytes solides de type borate de lithium. Une corrélation entre la conductivité ionique et le coefficient de dilatation thermique (CTE) a été mise en évidence pour différentes compositions de verres massifs. A partir des résultats de CTE obtenus, un modèle de prédiction basé sur les travaux de Appen permettant la détermination de ce dernier en fonction de la composition chimique a été développé. Dans un second temps, différentes techniques de préparation de cibles denses nitrurées ont été mises en œuvre afin d'abaisser le CTE de la cible et ainsi permettre son utilisation sur une plus longue durée. Par ailleurs, l'utilisation d'une cible nitrurée a également été envisagée pour augmenter la teneur en azote dans les couches minces. Finalement, des couches minces d'électrolyte de différentes compositions ont été préparées par pulvérisation cathodique (sous plasma d'argon ou d'azote pur) et ont fait l'objet d'une caractérisation chimique, structurale, électrique et thermomécanique. Le rôle bénéfique de l'azote sur la conductivité ionique des couches minces a ainsi pu être confirmé.
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Martin, Lucile. "Etude de l'oxyde de cuivre CuO, matériau de conversion en film mince pour microbatteries au lithium : caractérisation des processus électrochimiques et chimiques en cyclage." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3027/document.
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La miniaturisation des appareils électroniques et la multiplication de leurs fonctionnalités conduisent à développer des microsources d’énergie adaptées, parmi lesquelles figurent les microbatteries au lithium. Malgré leurs excellentes performances, ces systèmes de stockage électrochimique tout solide restent toutefois limités en termes de capacité surfacique. Cette caractéristique étant intrinsèquement liée aux matériaux d’électrodes, nous avons choisi de nous intéresser à des couches minces de CuO, dont la capacité volumique théorique (426 µAh .cm-2.µm-1) est sensiblement plus élevée que celle des matériaux d’intercalation utilisés jusqu’à présent. Ce matériau réagit avec le lithium selon un mécanisme particulier, dit de conversion, qui induit la formation d’un système multiphasé et nanostructuré d’une grande complexité. Dans le cadre de ce travail, la compréhension des mécanismes électrochimiques et chimiques mis en jeu au cours du cyclage de couches minces d’oxyde de cuivre (CuO) a été l’objectif majeur. Celui-ci a nécessité une caractérisation fine du matériau actif d’électrode et des interfaces générées (interfaces solide/solide et interface solide/électrolyte). Ces études ont été principalement menées à partir de la Spectroscopie Photoélectronique à Rayonnement X (XPS), de la Microscopie à Force Atomique (AFM) et d’une modélisation théorique exploitant les méthodes de la chimie quantique. Les propriétés chimiques et morphologiques des couches minces de CuO cyclées ont été corrélées à leur comportement électrochimique. Une forte influence de leur structure et de leur morphologie initiales a pu être ainsi mise en évidenceThe miniaturization of electronic components and the increasing number of their functionalities lead to the development of suitable energy microsources, among which lithium microbatteries appear. Despite the excellent performances of these all-solid-state electrochemical power sources, one main limitation that remains is their surface capacity. Its value being intrinsically connected to the nature of electrode materials, we chose to focus on CuO thin films which are characterized by a theoretical volumetric capacity (426 µAh .cm-2.µm-1) in far larger than the one of conventional intercalation materials used today. Indeed, this material reacts with lithium according to a particular mechanism, referred as conversion reaction, inducing the formation of a multiphase nanostructured system with a high complexity. In the framework of this study, understanding of electrochemical and chemical mechanisms which take place during the cycling of copper oxide thin films (CuO) was the main objective. This one has required a fine characterization of the electrode active material and the generated interfaces (solid/solid interfaces and solid/electrolyte interface). These studies have been mainly carried out with X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and theoretical approaches based on quantum chemistry methods. The chemical and morphological properties of the cycled CuO thin films have been linked to their electrochemical behavior. An important influence of their initial structure and morphology was then evidenced
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Gavanier, Beatrice. "Stability of thin film insertion electrodes." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324003.
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Liao, Feng. "Relation entre caractéristiques morphologiques et chimiques interfaciales et comportement électrochimique de couches minces de sulfures métalliques pour batteries li-ion : = Relation between morphological and chemical interfacial characteristics and electrochemical properties of metallic sulfides thin films for lithium ion batteries." Paris 6, 2013. http://www.theses.fr/2013PA066126.
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Les mécanismes de lithiation électrochimique, de passivation et de vieillissement de sulfures métalliques (Fe1-xS (0≤x≤0. 07), Ni3S2 et Cu2S) ont éte�� étudiés par spectroscopie de surface (XPS et ToF-SIMS) couplée à des mesures électrochimiques. Une approche modèle des matériaux d’électrode négative de type conversion pour les batteries Li-ion a été développée. Elle repose sur l’élaboration de films minces de sulfure par croissance en milieu H2S sur substrat métallique. Le substrat sert de collecteur de courant. Les résultats montrent que la conversion/déconversion avec le lithium est réversible mais incomplète. La décharge conduit à la passivation de la surface du matériau avec formation d’une couche interfaciale (SEI) dont la composition, la stabilité et l’épaisseur ont été suivies durant le premier cycle puis en cyclage répété. Le gonflement/rétrécissement, typique des matériaux de type conversion, génère des modifications morphologiques (fissures et trous) amplifiées par cyclage répété. Un modèle mécanistique des modifications de l’électrode incluant l’influence de l’électrolyte est proposéSurface analytical techniques were combined to study the electrochemical lithiation, passivation and ageing mechanisms of transition metal sulfides (Fe1-xS (0≤x≤0. 07), Ni3S2 and Cu2S) as conversion-type negative electrode materials for Li-ion batteries. A thin film approach was applied by thermal sulfidation of metal substrate used as current collector. The results show reversible but incomplete conversion/deconversion with lithium. Discharge leads to surface passivation with formation of the solid electrolyte interphase (SEI) layer whose chemical composition, stability and thickness were followed during the first cycle and with repeated cycling. Swelling/shrinkage, typical for conversion-type materials, causes irreversible morphological modifications (cracks and pinholes) amplified by multi-cycling. A mechanistic model of the induced thin film electrode modifications including the electrolyte influence is proposed
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Mui, Simon C. 1976. "Electrochemical kinetics of thin film vanadium pentoxide cathodes for lithium batteries." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33607.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.Includes bibliographical references (p. 147-154).
Electrochemical experiments were performed to investigate the processing-property-performance relations of thin film vanadium pentoxide cathodes used in lithium batteries. Variations in microstructures were achieved via sputtering and anneal treatments, resulting in films with different morphologies, grain size distributions, and orientations. Key findings included (1) grain size distributions largely did not affect the current rate performance of the cathodes. Rather, the film orientation and the ability to undergo rapid phase transformation were more vital to improving performance; (2) interfacial resistance and ohmic polarization were also dominant at the high current rates used (> 600 [mu]A/cm²) in addition to solid diffusion; and (3) optimization of thin film batteries requires that film thickness be < 500 nm to avoid diminishing returns in power and energy densities. Kinetic parameters including the transfer coefficient ([alpha] = 0.90± 0.05) and standard rate constant (k⁰ [approx.] 2 x 10⁻⁶ cm/s) for vanadium pentoxide films were quantified using slow scan DC cyclic voltammetry and AC cyclic voltammetry. The reaction rate was found to be potentially limiting at moderate to high current rates (> 200 [mu]A/cm²).
(cont.) An analysis of the wide variation in current-rate performance for different V₂0₅ architectures (including composite, nanofiber, and thin film) shows a convergence in results when the area of active material has been factored into the metric. This convergence suggests that either the reaction rate or interfacial resistance is limiting in V₂0₅ as opposed to diffusion.
by Simon C. Mui.
Ph.D.
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Li, Chiung-Nan. "Microstructural stability of nanocrystalline LiCoO₂ cathode in lithium thin-film batteries." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1580828921&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Moulki, Hakim. "Matériaux et dispositifs électrochromes à base de NiO modifié en couches minces." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00989588.
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Ce travail de thèse a été réalisé dans le cadre du programme européen INNOSHADE, dont l'objectif était la réalisation de dispositifs électrochromes à coloration neutre. Cette coloration neutre est le résultat de l'association dans un même dispositif de la couleur marron de films à base d'oxyde de nickel avec celle bleue de films d'oxyde de tungstène ou de PEDOT. Nos recherches ont été orientées vers des films minces d'oxyde de nickel modifié contenant des ions nickel trivalent, alliant porosité et désordre structural. Deux techniques de dépôt ont été utilisées : l'ablation laser et le trempage-retrait (dip-coating). Des processus de coloration et de décoloration de ces films en milieux liquides ioniques hydrophobes lithiés et non lithiés, faisant intervenir la participation d'anions tels que TFSI-, ont été mis en évidence pour la première fois dans cette thèse. Les dispositifs tout solides correspondants présentent des efficacités optiques élevées et une bonne durabilité.
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Shi, Z., L. Lü, and Gerbrand Ceder. "Solid State Thin Film Lithium Microbatteries." 2003. http://hdl.handle.net/1721.1/3672.
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Solid state thin film lithium microbatteries fabricated by pulsed-laser deposition (PLD) are suggested. During deposition the following process parameters must be considered, which are laser energy and fluence, laser pulse duration, laser pulse frequency, target composition, background gasses, substrate temperature, target-substrate distance and orientation. The effects of the variations of the process parameters can be obtained by measuring stoichiometry, thickness, phases and structure (grain size and texture), and stress of the deposited films. Electrochemical measurements will be conducted to test the microbattery properties through open-circuit voltage, charge-discharge cycling, cyclic voltammetry, and impedance analysis.Singapore-MIT Alliance (SMA)
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Chen, Jing. "Electrical and switching characteristics of lithium niobate thin films." Thesis, 1996. http://hdl.handle.net/1911/14058.
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C-V and I-V measurements combined with pulse application were employed to study the electrical characteristics of lithium niobate thin film samples. Though the C-V measurements showed some classical features, a lithium drifted n-i-p junction model was postulated to explain the low nominal dielectric constant in C-V characteristics. The I-V characteristics were analyzed and the field dependence was determined to be Frenkel-Poole emission at low field and possibly Fowler-Nordheim at high field.
A four-pulse dual-polarity pulse train was then used to study the switching kinetics of these thin films. The resulting transient current was captured and unstable switching was found in some samples. The polarization reversal was found to be dominated by forward domain growth with virtually no sideways motion. Finally, some important time constants such as nucleation time and domain wall growth time were determined and analyzed.
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Stone, Barbara Ann. "Physical characterization of lithium niobate thin films on silicon substrates." Thesis, 1988. http://hdl.handle.net/1911/13320.
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The structure and orientation of radio frequency sputtered lithium niobate (LiNbO$\sb3$) films on silicon substrates is determined using x-ray diffraction. The structure of the LiNbO$\sb3$ films is determined to be a strong function of the substrate temperature. The preferred crystal orientation of the film is found to depend on the substrate orientation. Of particular importance is the observation of LiNbO$\sb3$ polycrystalline films oriented with the c axis of the crystallites normal to the surface of $\langle$111$\rangle$ silicon substrates. This result is important since the ferroelectric polarization and photocurrents are directed along the c axis of crystal, making the development of ferroelectric memory devices using LiNbO$\sb3$ possible. Scanning electron microscopy revealed that the films were generally smooth, and no ferroelectric domain contrast was observed. Ellipsometry was used to determine the refractive indices and thicknesses of the films.
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Wang, Shunxi. "Lithium niobate thin films on diamond substrates for SAW devices." Thesis, 2001. http://hdl.handle.net/1911/18047.
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Lithium niobate thin films have been grown on diamond/silicon substrates by metallo-organic decomposition and radio frequency (R. F.) magnetron sputtering. The surface acoustic wave (SAW) characterizations of the multilayer lithium niobate/diamond/silicon are calculated. The lithium niobate thin films as well as the diamond/silicon substrates are structurally analyzed using techniques such as Bragg X-ray diffraction, scanning electron microscopy, atomic force microscopy, electron microprobe, and Raman spectroscopy to determine their crystal structure, surface morphology and composition distribution. With the use of a lift-off photolithography planar process, surface acoustic wave filter devices on substrates such as lithium niobate single crystal plates, zinc oxide/diamond/silicon, and lithium niobate/diamond/silicon, are fabricated. Microwave characterizations, such as the frequency response, of these filters are measured, and their impulse response in the time domain are obtained by fast Fourier transformation. SAW activities for LiNbO3/diamond/silicon structure are observed. Discussions about the results and further improvements are presented.
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CHOLAPRANEE, TARA. "INVESTIGATION OF LITHIUM - NIOBIUM TRIOXIDE THIN FILMS IN MIS STRUCTURE (FERROELECTRIC)." Thesis, 1986. http://hdl.handle.net/1911/15964.
Full textAbstract:
Thin film LiNbO(,3) was deposited on silicon substrates by using r.f. sputtering techniques under different conditions. A set of films was deposited with different substrate temperatures and with different gas mixtures between O(,2) and Ar to study the effect on crystallinity and electrical properties. X-ray diffraction was used to study the crystal structures of the films. It was found that good polycrystalline films were obtained when O(,2) and Ar were used at the equal partial pressures and the substrate temperature was raised to above about 550(DEGREES)C. At the substrate temperature much below 550(DEGREES)C the film is amorphous.
The bulk photovoltaic effect was studied in these films. I-V characteristics under dark and illuminated conditions indicated that there was a photovoltaic effect in these films. The saturation field was estimated to be about 4.1 KV/cm and the short-circuit photocurrent was 9 pA at the light intensity 29 mW/cm('2). The low saturation field was attributed to the high photoconductivity of the thin film. The transient photocurrent was also studied and it was attributed to the pyroelectric effect.
C-V and G-V characteristics under dark and post-illuminated conditions confirmed that the photovoltaic effect was indeed the bulk photovoltaic effect. C-f and G-f characteristics had different features at low frequency for polycrystalline and amorphous films. For the amorphous film (sample 17c), the capacitance varied as 1/SQRT.((omega)) and the conductance varied as SQRT.((omega)). For the polycrystal- line film sample 16c, the capacitance almost did not change with frequency. The conductance varied with the frequency faster than that of the amorphous film, and close to the frequency dependence of the conductance calculated from the second circuit model given in fig. 5.9 b).
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Hwang, Fu-Tsai, and 黃富財. "The Study of Lithium Niobate Thin Films by RF Sputtering Method." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/35494896255427060073.
Full textAbstract:
博士國立中央大學
光電科學研究所
94
Abstract Very high quality LiNbO3 films were deposited on both silicon and quartz substrates for the applications of surface acoustic wave and optical waveguide by RF magnetron sputtering. We have investigated the dependence of the surface morphology, texture, crystallinity, thickness, refractive index, extinction coefficient properties with the sputtering parameters and annealing process. The optimum deposition temperature was measured by differential thermal analysis. The crystallinity was examined by x-ray and low angle x-ray diffractometer (XRD). The roughness of LiNbO3 thin films was examined by atomic force microscopy (AFM). AFM and XRD measurements were used to investigate the mechanisms of the variation in the surface morphology and crystallinity of LiNbO3 thin films.The optimum deposition temperature was found to be about 575℃. In this investigation the optimum ratio of the mass flow Ar/O2 was found to be about 1:1. Simultaneously, the RF power necessary for texture was found to be about 100W. The thickness, refractive index and extinction coefficient of LiNbO3 thin films were examined by ellipsometer. We have found the refractive index (n) is 2.2 (at 632.8nm), which is identical with the parameter of LiNbO3 ever reported. At the same time, the extinction coefficient of LiNbO3 thin films approachs to zero , represents that these thin films are suitable for optical waveguides.
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Kim, Yoon Gu. "Plasma-assisted directed vapor deposition for synthesizing lithium phosphorus oxynitride thin films /." 2008. http://wwwlib.umi.com/dissertations/fullcit/3327009.
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An-Chi, Huang, and 黃安祺. "The Study of Lithium Niobate High Dielectric Thin Films by RF Sputtering." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/52542511711495769396.
Full textAbstract:
碩士國立雲林科技大學
電子與資訊工程技術研究所
86
In this thesis, Lithium Niobate (LiNbO3) thin films were deposited by radio-frequency (RF) magnetron sputtering. The material and electric properties of the deposited LiNbO3 films were investigated. Lithium Niobate thin films were prepared on p-type Si (100) substrates. Post-deposited thermal treatments with various conditions were applied to the LiNbO3 films. Al/LiNbO3/Si (MIS) structure was fabricated to measure the electrical properties. LiNbO3 films were investigated from the viewpoint of leakage current density, dielectric constant and dielectric breakdown strength. According to the C-V and I-V measurements, the dielectric constant was estimated to be 41 and the leakage current density was observed to be 5×10-7 A/cm2 at 1.5 V bias for the 50-nm-thick LiNbO3 film annealed at 600℃, 30 minutes in N2 ambient. The dielectric breakdown strength is as high as 28 MV/cm at 25℃. At the electric field E = 1 MV/cm, TBD is determined to be about 12 years.
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Zhu, Jie. "Processing and characterization of lithium niobate thin films for ferroelectric nonvolatile memory applications." Thesis, 2002. http://hdl.handle.net/1911/17566.
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Both highly c-axis and randomly-oriented LiNbO3 thin films are grown on p-type Si (111) substrates by RF magnetron sputtering and metallo-organic decomposition (MOD), respectively. Ellipsometry, X-ray diffraction, AFM and SEM are used to analyze the structural quality of the deposited ferroelectric thin films, including thickness, crystallinity, stoichiometry and surface roughness. Metal-ferroelectric-semiconductor structures are fabricated and electrically characterized with polarization vs. electric field (P-E) and capacitance vs. voltage (C-V) measurements. Hysteresis curves based on polarization switching are observed, verifying the ferroelectricity of deposited LiNbO3 thin films. Comparison of different film growth mechanisms between these two deposition methods is made, and their effects on physical and electrical characteristics of the derived LiNbO3 thin films are discussed. RF magnetron sputtering is proved to be a more promising thin-film growth technique than MOD for ferroelectric nonvolatile memory applications.
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Wang, Xuguang. "Electrical characterizations of lithium niobate thin films in a metal-ferroelectric-semiconductor capacitor." Thesis, 2002. http://hdl.handle.net/1911/17559.
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A LiNbO3 thin film Metal-Ferroelectric-Semiconductor capacitor is analyzed with various electrical characterization methods for studying the polarization switching and the thin film conduction behavior. The polarization density vs. electric field (P-E) curve shows that the remnant polarization is 16.85muC/cm2 and the coercive field is 117.25 KV/cm when maximum applied field is 286.2KV/cm for a sinusoidal input waveform. The capacitance vs. voltage bias (C-V) curve further demonstrates that the polarization charge is the dominant charge in controlling the ferroelectric semiconductor interface property. The switching transient current curve from a dual polarity four pulses chain study (P-S) gives the switching time of the sample about 80--100ns. Current vs. voltage (I--V) curve is explained with a back-to-back Schottky barrier controlled conduction mechanism. These electrical characterization results demonstrate that LiNbO3 is a promising candidate for a Metal-Ferroelectric-Semiconductor-Field-Effect-Transistor (MFSFET) non-volatile non-destructive memory application.
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Lin, Albert Jian. "Lithium niobate thin films deposited on silicon substrates for SAW applications (surface acoustic wave)." Thesis, 1996. http://hdl.handle.net/1911/14063.
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Lithium niobate has a number of attractive piezoelectric and ferroelectric properties that have been exploited for several different applications. The main purpose of this work is to produce lithium niobate thin films on silicon substrates (with amorphous SiO$\sb2$ coating) and to make low insertion loss surface acoustic wave (SAW) devices. For SAW devices, the insertion loss mainly relates to the electromechanical coupling coefficient (K$\sp2$) of the materials. To get low insertion loss in SAW devices, we need use high K$\sp2$ materials. Among common piezoelectric materials, lithium niobate has the highest K$\sp2$ value. Theoretical curves of SAW properties of lithium niobate bulk crystals and films on SiO$\sb2$(amorphous)/Si(100) were obtained. Thin films of lithium niobate have been deposited on SiO$\sb2$(amorphous)/Si(100) substrates by rf magnetron sputtering. The film samples were structurally analyzed by x-ray diffraction (XRD). Lithium niobate XRD peaks (012), (104) and (110) were identified. Highly textured lithium niobate film samples with very good transparency and uniformity were obtained.
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Shih-AnWang and 王時安. "Effects of dopants in silicon thin films on the performance of lithium-ion battery." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/24233670003477911679.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系
104
Purified silicon without impurities is bound to exhibit low conductance. When pure silicon is employed as an active material for lithium-ion battery, the performance of the battery is always poor because of the low conductivity. To enhance the performance of silicon anode lithium-ion battery, we intend to investigate the doping effect in silicon on batteries performance. Our approach is conducted through silicon thin film deposited by electron beam evaporation, when silicon targets are prepared by grinding various type of silicon wafer, including undoped silicon, p-type silicon and n-type silicon into small pieces. We successfully deposit silicon films on copper substrate with good adhesion. Scanning Electron Microscopy, Multipurpose X-Ray Thin-Film Diffractometer and Transmission Electron Microscopy are used to investigate the crystallinity of the as-deposited silicon films. Secondary Ion Mass Spectrometer is employed to confirm the existence and distribution of impurities in the silicon films. Four-point probe measurement method is used to measure the resistance of the as-deposited silicon thin films. After finishing material characterization, lithium metal is adopted as reference electrode, while silicon thin film is taken as test electrode. Coin cells is studied by electrochemical test to study doping effect by observing battery performance. Electrochemical impedance spectroscopy is also used to measure the impedance change between 20cycles and 200cycles of silicon anode coin cell. The coin cells after of 3cycles and 100cycles are dissembled to studied the morphology change of silicon active materials during charge and discharge.