Neste trabalho foram estudadas diferentes modificações superficiais do titânio (Ti) como método de preparação de superfícies de eletrodos para baterias de íons lítio (Li+) Inicialmente, as modificações foram produzidas pelas micro-indentações, com posterior corrosão eletroquímica por pites em soluções de brometo. As superfícies polidas, tratadas termicamente e modificadas através de micro-indentações foram avaliadas em diferentes parâmetros, tais como o potencial aplicado, concentração dos íons agressivos no eletrólito, temperatura, tempo dos testes e principalmente, sobre o impacto das deformações causadas pela força indentações para localização de orifícios produzidos por pites. Filmes porosos de titânia (TiO2) crescidos sobre o Ti puro, foram produzidos por anodização a plasma (anodização por centelhamento ou sparking) em 1M H3PO4 e em 1M Na2SO4 e por anodização nanotubular em 1M H3PO4 + 1M NaOH + 0,4 %(peso) HF. Os resultados mostraram, em óxidos tipo “esponja” formados na anodização a plasma em 1M H3PO4 e 1M Na2SO4, a incorporação de elementos do eletrólito contendo, respectivamente, P e S, numa relação de P/O > S/O e em óxidos nanotulares, a predominante incorporação de elemento de F. Posteriormente, as superfícies corroídas por pites e as superfícies de óxidos crescidos por anodização a plasma foram convertidas por sulfetação em diferentes materiais micro e nanoestruturados compostos por sulfetos e oxisulfetos de titânio, ajustando-se as condições de processo. O desenvolvimento proposto mostrou que é possível modificar a composição química do óxido formado por anodização a plasma para nanocristais de TiS2, nanofitas de TiS3 e TiOxSy, sem danificar a morfologia original dos nanoporos de TiO2. Os compostos formados podem ser usados como eletrodos nanoarquiteturados tridimensionais (3D) para microbaterias de íons lítio (Li+) com alta densidade de potência. A síntese desses compostos é realmente promissora, porque eles têm a capacidade de inserir mais íons lítio do que TiO2 puro, resultando em uma melhoria na capacidade das microbaterias. / In this study, different surface modifications of titanium (Ti) were studied as a method of surface preparation of electrodes for ion lithium batteries (Li+). Initially, the modifications were produced by micro-indentation with subsequent electrochemical pitting corrosion in solutions of bromide. The polished surfaces, heat treated and modified through micro indentations were evaluated for different values of parameters, such as applied potential, concentration of aggressive ions in the electrolyte, temperature, polarization time, and mainly intensity of the deformation caused by indentations for localizing holes produced by pitting. It was expected the adjust of location of these parameter settings promotes nucleation of pits, according to the pattern of indentations and growth of pitting depth for increased surface area. Porous films of titania (TiO2) were produced on pure Ti by plasma anodization (or sparking) in 1M H3PO4 and 1M Na2SO4. Nanotubes were synthesized by porous anodization in 1M NaOH + 1M H3PO4 + 0.4 (wt%) HF. The results showed oxide "sponge" like formed by plasma anodization, incorporating elements of the electrolyte containing respectively, P and S in a ratio P/O> S/O and, in nanotubular oxides, with predominant incorporation of F. Subsequently, the pitted surfaces and the surfaces of oxides grown by plasma anodization were converted by sulfidation into different micro and nanostructured materials consisting of titanium sulfide and oxisulfides by adjusting the process conditions. The proposed development has shown that it is possible to modify the chemical composition of the oxide formed by plasma anodizing to nanocrystals of TiS2 and nanobelts of TiS3 and TiOxSy without damaging the original morphology of the nanoporous TiO2. The formed compounds can be used as three-dimensional (3D) nanoarchitectured electrodes for ion lithium batteries (Li+) with high power density. The synthesis of these compounds is promising due to a higher ability to intercalate more ions lithium than pure TiO2, resulting in an improvement in the capacity of microbatteries.

Made available in DSpace on 2014-06-11T19:26:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-15Bitstream added on 2014-06-13T20:47:03Z : No. of bitstreams: 1 stetner_abo_me_bauru.pdf: 468326 bytes, checksum: 98097b70a204ef6b2bf5399976184c07 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As organizações têm enfrentado desafios relacionados à produtividade, desenvolvimento sustentável, posicionamento estratégico, motivação e bem estar de seus empregados. Neste contexto, o desempenho de Sistemas de Segurança e Saúde no Trabalho (SSST) ganha um significado cada vez mais importante nos resultados das empresas por meio da redução dos riscos de acidentes e promoção da saúde e da satisfação dos trabalhadores. No entanto, para que um SSST obtenha bons resultados, as organizações precisam estar atentas às dificuldades comumente encontradas durante o seu processo de implantação, procurando solucioná-las de maneira antecipada e estruturada. Pelo exposto, esta dissertação tem como objetivo elaborar recomendações baseadas no referencial teórico e nas boas práticas e dificuldades evidenciadas nos estudos de caso, que contribuiam com a implantação de sisteamas de segurança e saúde no trabalho em empresas fabricantes de baterias automotivas. Para o desenvolvimento da pesquisa optou-se pelo método de pesquisa qualitativa com base na elaboração de dois estudos de caso em empresas localizadas na cidade de Bauru. Os instrumentos de coleta de dados utilizados foram entrevistas semi-estruturadas, análise de documentos e observação in loco. Ao final da dissertação são propostas recomendações para implantação deste sistema relacionadas aos seguintes elementos: alta direção, estratégia organizacional, cultura organizacional, departamento de segurança e saúde do trabalho, técnicos de segurança e saúde do trabalho, recursos humanos, treinamentos, equipes multidisciplinares para solução de problemas de segurança e saúde do trabalho, comunicação interna, resistência à mudança, indicadores de desempenho, ferramentas gerenciais para solução de problemas, gestão de projetos, recompensas e incentivos, e integração dos sistemas. / Organizations have been facing challenges related to their employees' productivity, sustainable development, strategic positioning, motivation and welfare. In such a context, the occupational health and safety systems gains an ever-present major relevance in the companies' results, through the reduction of occupational hazards and the fostering of their workers' health and self-fulfillment. Nevertheless, for the occupational health and safety systems to achieve good results, organizations must be attentive to the difficulties they frequently have to overcome along their implantation process, by seeking to solve them in a structure in-advance manner. As already outlined, this dissertation has a its main purpose the development of suggestions based upon the theoretical referential and on the good practices and difficulties avidenced in the case studies, wich may contribute towards the implantation of the occupational health and safety systems in those companies which manufacture automotive batteries. The qualitative research method was chosen for the development of this work, relying on two case studies in companies in the city of Bauru. The data collection tools used were semi-structured interviews, documents analysis and in loco observation. At the end of this dissertation, suggestions are given for the implantation of such system, related to the elements which follow: high administration, organizational strategy, organizational culture, a department of the occupational health and safety with its respective technicians, human resources, training, multidisciplinary teams for solving the occupational health and safety problems, internal communication, resistance to changes, performance indicators, problem-solving managerial tools, management of projects, rewards and incentives, and also integration to the systems.

L’étain est une alternative privilégiée en remplacement du carbone graphite comme matériau d’électrode négative dans les batteries Li-ion en raison de son importante capacité théorique spécifique massique de 993 mAh.g-1. Toutefois son expansion volumique lors sa lithiation conduit à sa dégradation au cours du cyclage, diminuant la durée de vie du matériau. Pour pallier à sa pulvérisation, l’utilisation de l’espace inter-granulaire via la nanostructuration du matériau est complétée par l’adjonction d’une matrice carbonée ou d’un autre élément inactif vis-à-vis de la lithiation (utilisation d’alliages intermétalliques). L’objectif de ce travail porte sur l’élaboration de nouveaux procédés de synthèse de nanoparticules d’étain et d’alliage étain-cuivre en milieu liquide ionique. Des nanoparticules de Sn de taille variant de 7 à 45 nm, selon la combinaison cation-anion du liquide ionique et à partir de différents sels métalliques, ont été synthétisées, ainsi qu’un nano-alliage, le composé Cu6Sn5. La taille des nanoparticules est liée à la nature de l’anion bien que le cation présente une interaction privilégiée avec la surface métallique des nanoparticules. Isolées du liquide ionique, les nanoparticules de Sn et Cu6Sn5 montrent une architecture de type cœur-coquille avec un cœur cristallin métallique ou intermétallique et une coquille amorphe d’oxydes d’étain. Les nanoparticules de type Sn@SnOx présentent une capacité spécifique élevée supérieure à 950 mAh.g-1, mettant en lumière un mécanisme de conversion réversible du SnOx surfacique, et celle du nano-alliage Sn-Cu@SnOx est proche de la capacité attendue pour un mécanisme d’alliage, à plus de 530 mAh.g-1. / Tin is a promising alternative to replace graphite carbon as a negative electrode material in Li-ion batteries due to its high specific theoretical mass capacity of 993 mAh.g-1. However, change in volume during lithiation leads to its mechanical degradation during the cycling, and consequently very short life of the material. To overcome this issue, the use of the intergranular space via the nanostructuration of the material combined by the addition of a carbon matrix or other inactive element vs. lithium (intermetallic alloys), which buffers drastically the volume expansion during the lithium alloying process, is employed. The aim of this work is to develop new processes for the synthesis of tin nanoparticles and tin-copper alloys in ionic liquid medium. Sn nanoparticles varying in size from 7 to 45 nm were synthesized, according to the cation-anion combination of the ionic liquid and from different metallic salts, as well as a nano-alloy compound, Cu6Sn5. The size of the nanoparticles is directly related to the nature of the anion although the cation has a privileged interaction with the metal surface of the nanoparticles. Once isolated from the ionic liquid, Sn and Cu6Sn5 nanoparticles have a core-shell architecture with a metallic or intermetallic crystalline core and an amorphous shell of tin oxides. A reversible conversion mechanism of the SnOx from the shell is highlighted for Sn@SnOx nanoparticles, with a high specific capacity of approximately 950 mAh.g-1. Sn-Cu@SnOx nano-alloys have a capacity close to the theoretical for an alloy mechanism at more than 530 mAh.g-1.

abstract: There is a fundamental attractiveness about harnessing renewable energy in an age when sustainability is an ethical norm. Lithium ion batteries and hydrogen fuels are considered the most promising energy source instead of fossil fuels. This work describes the investigation of new cathode materials and devices architectures for lithium ion batteries, and photocatalysts for their usage in water splitting and waste water treatment. LiCoO2 and LiNi1/3Mn1/3Co1/3O2 were exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into functional cathode materials with microwave hydrothermal assistance, indicating that new cathodes can be obtained by reassembling nanosheets. This method can pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks. Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions. Origami lithium-ion battery made in this method that can be deformed at an unprecedented high level, including folding, bending and twisting. Spray pyrolysis was used to prepare films of AgInS2 with and without Sn as an extrinsic dopant. The photoelectrochemical performance of these films was evaluated after annealing under a N2 or S atmosphere with different amounts of the Sn dopant. Density Function Theory (DFT) was used to calculate the band structure of AgInS2 and understand the role of Sn doping in the observed properties. Cr(VI) removal was investigated using multiple oxide photocatalyst and additives. The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. While sulfite alone can chemically reduce Cr(VI), sulfite in combination with a photocatalyst resulted in faster and complete removal of Cr(VI) in 10 min using a SO32−/Cr(VI) ratio >35 in pH ∼ 8 solutions. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2016

abstract: Lithium ion batteries prepared with a ceramic separator, have proven to possess improved safety, reliability as well as performance characteristics when compared to those with polymer separators which are prone to thermal runaway. Purely inorganic separators are highly brittle and expensive. The electrode-supported ceramic separator permits thinner separators which are a lot more flexible in comparison. In this work, it was observed that not any α-alumina could be used by the blade coating process to get a good quality separator on Li4Ti5O12 (LTO) electrode. In this work specifically, the effect of particle size of α-alumina, on processability of slurry was investigated. The effect of the particle size variations on quality of separator formation was also studied. Most importantly, the effect of alumina particle size and its distribution on the performance of LTO/Li half cells is examined in detail. Large-sized particles were found to severely limit the ability to fabricate such separators. The α-alumina slurry was coated onto electrode substrate, leading to possible interaction between α-alumina and LTO substrate. The interaction between submicron sized particles of α-alumina with the substrate electrode pores, was found to affect the performance and the stability of the separator. Utilizing a bimodal distribution of submicron sized particles with micron sized particles of α-alumina to prepare the separator, improved cell performance was observed. Yet only a specific ratio of bimodal distribution achieved good results both in terms of separator formation and resulting cell performance. The interaction of α-alumina and binder in the separator, and its effect on the performance of substrate electrode was investigated, to understand the need for bimodal distribution of powder forming the separator. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2017

abstract: The automotive industry is committed to moving towards sustainable modes of transportation through electrified vehicles to improve the fuel economy with a reduced carbon footprint. In this context, battery-operated hybrid, plug-in hybrid and all-electric vehicles (EVs) are becoming commercially viable throughout the world. Lithium-ion (Li-ion) batteries with various active materials, electrolytes, and separators are currently being used for electric vehicle applications. Specifically, lithium-ion batteries with Lithium Iron Phosphate (LiFePO4 - LFP) and Lithium Nickel Manganese Cobalt Oxide (Li(NiMnCo)O2 - NMC) cathodes are being studied mainly due to higher cycle life and higher energy density values, respectively. In the present work, 26650 Li-ion batteries with LFP and NMC cathodes were evaluated for Plug-in Hybrid Electric Vehicle (PHEV) applications, using the Federal Urban Driving Schedule (FUDS) to discharge the batteries with 20 A current in simulated Arizona, USA weather conditions (50 ⁰C & <10% RH). In addition, 18650 lithium-ion batteries (LFP cathode material) were evaluated under PHEV mode with 30 A current to accelerate the ageing process, and to monitor the capacity values and material degradation. To offset the high initial cost of the batteries used in electric vehicles, second-use of these retired batteries is gaining importance, and the possibility of second-life use of these tested batteries was also examined under constant current charge/discharge cycling at 50 ⁰C. The capacity degradation rate under the PHEV test protocol for batteries with NMC-based cathode (16% over 800 cycles) was twice the degradation compared to batteries with LFP-based cathode (8% over 800 cycles), reiterating the fact that batteries with LFP cathodes have a higher cycle life compared to other lithium battery chemistries. Also, the high frequency resistance measured by electrochemical impedance spectroscopy (EIS) was found to increase significantly with cycling, leading to power fading for both the NMC- as well as LFP-based batteries. The active materials analyzed using X-ray diffraction (XRD) showed no significant phase change in the materials after 800 PHEV cycles. For second-life tests, these batteries were subjected to a constant charge-discharge cycling procedure to analyze the capacity degradation and materials characteristics. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2017

Ce travail de thèse se base sur quatre matériaux modèles, de composition LiNi1/3Mn1/3Co1/3O2, qui différent de par leur microstructure. Le lien entre leur morphologie et les performances électrochimiques est étudié par la combinaison de la caractérisation exhaustive de leur microstructure, l’étude de leur comportement en batterie et la modélisation de leur réponse électrochimique. L’étape limitant le processus électrochimique est identifiée par voltampérométrie cyclique et nous montrons que la transition attendue d’une limitation par le transfert de charge à une limitation par la diffusion en phase solide a lieu à différents régimes selon la microstructure. Ce comportement est expliqué par l’utilisation d’outils de simulations numériques. Selon leur forme et leur agglomération, les cristallites agissent collectivement ou indépendamment les unes des autres. Ces résultats rationalisent les performances en puissance obtenues sur nos matériaux. Les résultats de simulation montrent également qu’une faible fraction de la surface développée est électroactive, ce qui remet en question la large utilisation de la surface BET dans la littérature. Nous montrons également que, si les matériaux poreux sont les plus performants en puissance gravimétrique, la tendance est inversée pour la puissance volumique. Les stratégies de nanostructuration largement employées, qui se basent sur la capacité spécifique pour caractériser les matériaux, ne doivent pas oublier faire oublier le compromis nécessaire entre surface développée et volume. / Four NMC materials are synthesized by co-precipitation. They exhibit a hierarchical architecture made of reasonably spherical agglomerates. One is constituted of flake-shaped, spatially oriented, crystallites that leave large apparent void spaces in the agglomerate, while the other results from the tight agglomeration of micron-sized cuboids. Porous material exhibits the best power performances. It is impossible to identify a geometrical parameter that predict performances, even after achieving the full characterization of the microstructures. Cyclic voltammetry reveals two behaviours depending on the shape of crystallites: processes limited by solid-state diffusion (cuboids) and the ones limited by charge transfer even at high rates (flake-shaped). This observation challenges active materials design strategies that assume diffusion as the limiting process of lithium intercalation. Focusing on enhancing kinetics could be the way to increase performances. Charge-transfer is first investigated by measuring electronic conductivities over a wide range of frequencies, allowing to discriminate relaxations arising at various length scales. We show that flake-shaped crystallites facilitate the motion of electrons at all scale levels compared to cuboids. Charge-transfer limitations originate from the electrolyte/material interface in materials exhibiting high surface areas. Numerical simulations reveal that BET measurements largely overestimate the actual electroactive surface, which is understood by HRTEM images of flake-shaped crystallites. Only a small percentage, limited to the edge plane is truly electroactive.

At the nuclear power plant in Forsmark, several different securitysystems are used. One of these systems comprises uninterruptiblepower supply (UPS) and consists of lead-acid batteries. The batteries are dimensioned to supply the load for two hours and are constantly charged. This to ensure they’re fully charged in case the regular power source fails. Discoveries have been made that the lifetime of the batteries are shorter than calculated and this thesis examines if the environmental temperature is the reason. Higher temperatures will cause the batteries to corrode more easily which leads to a decrease of the capacity of the batteries. The temperature have been logged in selected areas during two weeks in April 2018. The results have been compared to the meteorological temperature and analyzed together with capacity tests of the batteries. The batteries that have inferior results in the capacity tests are placed in spaces with high temperatures and needs to be cooled as soon as possible. In longterm, installation of a proper cooling system is recommended. To measure the temperature during several periods throughout the year ensures if the meteorological temperature affects the environment of the batteries. If so, more spaces where batteries are placed may need cooling during the hotter period of the year.

CAPES / Este trabalho traz um estudo da aplicação do conversor Full-Bridge bidirecional como um carregador de banco de baterias em um barramento CC de fontes de energia renováveis. O problema principal destas fontes é que são sazonais e não oferecem uma continuidade de fornecimento de potência. Assim, o uso de banco de baterias, conectado a um barramento CC compartilhado com outras fontes renováveis traz contribuições na continuidade do fornecimento de energia. O conversor proposto neste trabalho visa conectar o banco de baterias ao barramento CC e ao mesmo tempo que faz a integração dos modos de carga e descarga em um único conversor. Adicionalmente, para reduzir volume, é utilizado um transformador planar que oferece alta eficiência (máximo de 99,5%) e uma reduzida relação volume/potência. O conversor foi desenvolvido para carregar um banco de baterias de 192V. No modo de descarga, ele é suado para alimentar um barramento CC de 400V com uma potência máxima de 1,34kW. Apesar do uso do conversor full-bridge não ser novidade nestes tipos de aplicação, dois fatores serviram de motivação para este trabalho: o uso do transformador planar e a tendência mundial de integração de fontes renováveis. / This work presents a study of the application of the Full-bridge bidirectional DC converter as a battery bank charger in a DC bus of renewable energy sources. The main problem is that these sources are seasonal and do not offer a continuously power supply. Thus, the use of a battery bank connected to a DC bus shared with other renewable sources brings contributions in the continuity of power supply. The converter proposed in this work aims to connect the battery bank to the DC bus at the same time it integrates the charging and discharging modes into a single converter. Additionally, to reduce the volume, it is used a planar transformer that provides high efficiency (up to 99.5%) and a reduced volume/power ratio. The converter is designed to charge a bank of batteries of 192V. At the discharge mode, it is designed to feed a 400V DC bus with maximum power of 1.34 kW. Despite the use of the full-bridge converter is not new in these types of application, two factors served as motivation for this work: the use of planar transformer and the global trend of integration of renewable sources.

CAPES / Este trabalho traz um estudo da aplicação do conversor Full-Bridge bidirecional como um carregador de banco de baterias em um barramento CC de fontes de energia renováveis. O problema principal destas fontes é que são sazonais e não oferecem uma continuidade de fornecimento de potência. Assim, o uso de banco de baterias, conectado a um barramento CC compartilhado com outras fontes renováveis traz contribuições na continuidade do fornecimento de energia. O conversor proposto neste trabalho visa conectar o banco de baterias ao barramento CC e ao mesmo tempo que faz a integração dos modos de carga e descarga em um único conversor. Adicionalmente, para reduzir volume, é utilizado um transformador planar que oferece alta eficiência (máximo de 99,5%) e uma reduzida relação volume/potência. O conversor foi desenvolvido para carregar um banco de baterias de 192V. No modo de descarga, ele é suado para alimentar um barramento CC de 400V com uma potência máxima de 1,34kW. Apesar do uso do conversor full-bridge não ser novidade nestes tipos de aplicação, dois fatores serviram de motivação para este trabalho: o uso do transformador planar e a tendência mundial de integração de fontes renováveis. / This work presents a study of the application of the Full-bridge bidirectional DC converter as a battery bank charger in a DC bus of renewable energy sources. The main problem is that these sources are seasonal and do not offer a continuously power supply. Thus, the use of a battery bank connected to a DC bus shared with other renewable sources brings contributions in the continuity of power supply. The converter proposed in this work aims to connect the battery bank to the DC bus at the same time it integrates the charging and discharging modes into a single converter. Additionally, to reduce the volume, it is used a planar transformer that provides high efficiency (up to 99.5%) and a reduced volume/power ratio. The converter is designed to charge a bank of batteries of 192V. At the discharge mode, it is designed to feed a 400V DC bus with maximum power of 1.34 kW. Despite the use of the full-bridge converter is not new in these types of application, two factors served as motivation for this work: the use of planar transformer and the global trend of integration of renewable sources.