>Magister Scientiae - MSc / Spinel lithium manganese oxide (LiMn2O4), for its low cost, easy preparation and nontoxicity, is regarded as a promising cathode material for lithium-ion batteries. However, a key problem prohibiting it from large scale commercialization is its severe capacity fading during cycling. The improvement of electrochemical cycling stability is greatly attributed to the suppression of Jahn-Teller distortion (Robertson et al., 1997) at the surface of the spinel LiMn2O4 particles. These side reactions result in Mn2+ dissolution mainly at the surface of the cathode during cycling, therefore surface modification of the cathode is deemed an effective way to reduce side reactions. The utilization of a nanocomposite which comprises of metallic Cu and Au were of interest because their oxidation gives rise to a variety of catalytically active configurations which advances the electrochemical property of Li-ion battery. In this research study, an experimental strategy based on doping the LiMn2O4 with small amounts of Cu-Au nanocomposite cations for substituting the Mn3+ ions, responsible for disproportionation, was employed in order to increase conductivity, improve structural stability and cycle life during successive charge and discharge cycles. The spinel cathode material was synthesized by coprecipitation method from a reaction of lithium hydroxide and manganese acetate using 1:2 ratio. The Cu-Au nanocomposite was synthesized via a chemical reduction method using copper acetate and gold acetate in a 1:3 ratio. Powder samples of LiMxMn2O4 (M = Cu-Au nanocomposite) was prepared from a mixture of stoichiometric amounts of Cu-Au nanocomposite and LiMn2O4 precursor. The novel LiMxMn2O4 material has a larger surface area which increases the Li+ diffusion coefficient and reduces the volumetric changes and lattice stresses caused by repeated Li+ insertion and expulsion. Structural and morphological sample analysis revealed that the modified cathode material have good crystallinity and well dispersed particles. These results corroborated the electrochemical behaviour of LiMxMn2O4 examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The diffusion coefficients for LiMn2O4 and LiMxMn2-xO4 obtained are 1.90 x10-3 cm2 / s and 6.09 x10-3 cm2 / s respectively which proved that the Cu-Au nanocomposite with energy band gap of 2.28 eV, effectively improved the electrochemical property. The charge / discharge value obtained from integrating the area under the curve of the oxidation peak and reduction peak for LiMxMn2-xO4 was 263.16 and 153.61 mAh / g compared to 239.16 mAh / g and 120 mAh / g for LiMn2O4. It is demonstrated that the presence of Cu-Au nanocomposite reduced side reactions and effectively improved the electrochemical performance of LiMn2O4.

Cette étude s’inscrit dans le cadre de la recherche de nouveaux matériaux anodiques à forte capacité pour accumulateurs à ion lithium. Il y est décrit, la synthèse de systèmes graphite-étain obtenus par réduction, en présence de graphite à des taux variables, des chlorures d’étain SnCl2 et SnCl4, par les hydrures alcalins NaH et LiH activés par un alcoolate. Les nanomatériaux préparés présentent des capacités réversibles stables en cyclage, assez proches de celles calculées à partir des teneurs en métal déterminées par analyse élémentaire. Cependant, on peut noter des différences importantes entre les valeurs et l’évolution en cyclage des capacités irréversibles selon l’hydrure ou le mélange d’hydrure utilisé(s). Avec l’hydrure de sodium NaH, la capacité irréversible, très élevée au premier cycle, s’annule pratiquement dès le deuxième cycle ; avec l’hydrure de lithium LiH, cette capacité irréversible, bien que plus faible au premier cycle, donne une valeur résiduelle récurrente aux cycles suivants. Il a finalement été montré que l’utilisation du mélange des deux hydrures NaH/LiH permet de préserver les avantages des deux systèmes précédents et d’obtenir des matériaux combinant de manière synergique leurs propriétés. / This study is devoted to the development of new anodic materials with high capacities for lithium-ion batteries. The synthesis of graphite-tin systems obtained by reduction, in the presence of graphite at various rates, of the tin Chlorides SnCl2 and SnCl4, by the alkoxide-activated alkaline hydrides ( sodium hydride or lithium hydride) is described. The nanomaterials prepared have stable reversible capacities in cycling, close to those calculated from the amounts of metal given by elemental analysis. However, important differences between the values and the evolution in cycling of the irreversible capacities depending on the hydride or the mixture of hydride used were observed. With sodium hydride, the irreversible capacity, very high during the first cycle, is practically cancelled at the second cycle; with lithium hydride, this irreversible capacity, although lower to the first cycle, gives a recurring residual value at the following cycles. The use of the NaH/LiH allowed to preserve the advantages of the two preceding systems and to synergistically combine their properties.

Structured electrodes with tailored nanoscale morphology and chemistry are highly desirable for a range of applications. In particular, emerging energy storage applications such as thick Lithium-ion battery (LIB) electrodes and photoanodes for watersplitting require new electrode structures that simultaneously optimise electron, ion, and thermal transport. In this PhD thesis, advanced structured electrodes are fabricated by creating 3D carbon-inorganic hybrid architectures. In this process, patterned vertically aligned carbon nanotubes (CNT) were used as the structural scaffolds to shape the electrodes while inheriting the excellent thermal and electrical properties of CNTs. First, UV and colloidal lithographic patterning processes were developed to create micro- and nanopores respectively within the CNT structures. Those structures provide high surface area and conductive backbone for the synthesis of hybrid CNT-inorganic structures. Specifically, the parameter space to create honeycomb shaped CNT structures with pores ranging from 300~nm to 30~$\mu$m has been established. Next, the micro-pore CNT structures have been chemically modified with iron oxide using microwave-assisted, hydrothermal synthesis for fabricating high areal loading LIB anodes. The areal loading was increased by 120\% compared to a standard battery film while at the same time retaining a high capacity (900 mAhg$^{-1}$ at 0.2 C). Then thick electrodes with optimised diffusion pathways were created by coating the nanopatterned CNTs with silicon using physical vapour deposition. These electrode structures are up to 50\% thicker than previously reported structures and still retain a stable capacity (650 mAhg$^{-1}$) and a good high-rate performance. Finally, the honeycomb shaped CNT structures have been coated with bismuth vanadate using a hotcasting process and the electrode architecture has been optimized for good conductivity by the addition of a Pd/Au layer between the CNTs and the BiVO$_{4}$. The photoelectrode performance was measured and shows a clear increase in current density when exposed to light. Each of these novel electrodes illustrate how patterning vertically aligned carbon nanotube structures combined with inorganic surface modification enables the creation of advanced electrodes with new formfactors and improved performance in comparison to literature and to classic drop-casted battery films of the same materials.

This thesis includes five main studies/ first, in order to enhance the conductivity of LiTi204, a new doping strategy is used and LiTi204−xCx ramsdellite is successfully fabricated. It is found that unit cell parameters a and b decline while c increases with more carbon inserted. The conductivity of LiTi204−xCx increases with more carbon insertion. Material with more carbon shows better reversibility and lower electrochemical polarization observed from potentiostatic curve. The material has better retention rate and rate ability with more carbon substitute doped. LiTi203.925C0.0375 has 151 mAh∙g−1 capacity under current density of 100 mAh∙g−1 and capacity decreased by 5.57% after 100 cycles. Second, in order to improve the capacity of LiTi204−xCx, Ti204−xCx is successfully fabricated through topotactic oxidation. It is found that the lattice parameters b and c decline while a keeps stable. With more carbon inserted, the retention ability increases. Ti01.9625C0.0375 has the capacity 320 mAh∙g−1 under 200 mAh∙g−1 and capacity retention loss by 9.1% per 100 cycles due to the balance of high conductivity and disordered channel resistance. Third, in order to study the process of lithium insertion, the structures and the atom sites of LiTi204−xCx ( R ) are obtained through refinement of the neutron diffraction patterns. The unit cell parameters a and b increase while c keeps stable for more lithium, atoms insertion. The channels for lithium insertion become wider and more round with lithium arranged in a line when x rises in the range of 0 < x < 0.5. When the x increases to 1, the channels turn into ordered parallelogram. Fourth, the lithium-contained spinelloid (a potential cathode material) is explored, but it is not found in this work. But spinels LI1−0.5xFe2.5xM1−xP1−xO4 (M=Fe, Co, Ni, Mn) are found and phosphorous insertion makes the structure stable during cycling. At last, to enhance the energy density, the 3D electrode is fabricated in in-situ growth by infiltration method. By powder infiltration, the load of activity material reaches over 60% of electrode mass. The morphology is porous and the particle size of the activity material is 20nm. The energy density based on LiCoO2 (250 WH∙g−1) is much higher than that of the traditional (200 WH∙g−1) 2D electrode reported.

Made available in DSpace on 2014-06-11T19:26:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-30Bitstream added on 2014-06-13T19:06:10Z : No. of bitstreams: 1 souza_cl_me_bauru.pdf: 1683744 bytes, checksum: 01408dd015968c885377375501713f24 (MD5) / Esta pesquisa tem como objetivo identificar as empresas produtoras de baterias automotivas esstão lidando com as barreiras e as motivações para a adoção de práticas de green supply chain managment (GSCM). O método de pesquisa utilizado foi o estudo de múltiplos casos nas cinco principais empresas produtoras de baterias automotivas instaladas no Brasil. Os resultados dessa pesquisa apontam que as principais práticas de GSCM adotadas pelas empresas estudadas são a gestão ambiental interna e a logística reversa e consequentemente as mais afetadas pelos fatores interno Processo de melhoria interno e externo Regulamentações Governamentais e Legislações. A forma como as empresas lidam com o fator interno é através da implantação de certificações, auditorias frequentes e respeito às exigências dos padrões de qualidade e, externamente é cumprido com as legislações e regulamentações vigentes e pertinentes ao setor. Adicionalmente, esta pesquisa apresenta guidelines para o setor de baterias automotivas instaladas no Brasil no que concernem as oportunidades e desafios para a adoção de práticas de GSCM / This research aims to identify how automotive batteries enterprisess are dealing with the barriers and drivers for the adoption of green supply chain management practices. The research method used was a multiple case study in five major automotive batteries enterprises installed in Brazil. The results of this study indicate that the main GSCM practices adopted by companies studied are internal environmental management and reverse logistics, and therefore most affected by internal factors Internal process improvement and external Government Regulations and Laws. The way companies deal with the internal factor is thorugh the deployment of certificates, frequent audits and compliance with the requirements of quality standards, and externally is complying with laws and regulations and relevant to the sector. Additionally, this research presents guidelines for the sector of automotive batteries enterprises installed in Brazil that concern the opportunities and challenges for the adoption of GSCM practices

Orientador: Ana Beatriz Lopes de Sousa Jabbour / Banca: Andrea Lago da Silva / Banca: Daniel Jugend / Resumo: Esta pesquisa tem como objetivo identificar as empresas produtoras de baterias automotivas esstão lidando com as barreiras e as motivações para a adoção de práticas de green supply chain managment (GSCM). O método de pesquisa utilizado foi o estudo de múltiplos casos nas cinco principais empresas produtoras de baterias automotivas instaladas no Brasil. Os resultados dessa pesquisa apontam que as principais práticas de GSCM adotadas pelas empresas estudadas são a gestão ambiental interna e a logística reversa e consequentemente as mais afetadas pelos fatores interno "Processo de melhoria interno" e externo "Regulamentações Governamentais e Legislações". A forma como as empresas lidam com o fator interno é através da implantação de certificações, auditorias frequentes e respeito às exigências dos padrões de qualidade e, externamente é cumprido com as legislações e regulamentações vigentes e pertinentes ao setor. Adicionalmente, esta pesquisa apresenta guidelines para o setor de baterias automotivas instaladas no Brasil no que concernem as oportunidades e desafios para a adoção de práticas de GSCM / Abstract: This research aims to identify how automotive batteries enterprisess are dealing with the barriers and drivers for the adoption of green supply chain management practices. The research method used was a multiple case study in five major automotive batteries enterprises installed in Brazil. The results of this study indicate that the main GSCM practices adopted by companies studied are internal environmental management and reverse logistics, and therefore most affected by internal factors "Internal process improvement" and external "Government Regulations and Laws". The way companies deal with the internal factor is thorugh the deployment of certificates, frequent audits and compliance with the requirements of quality standards, and externally is complying with laws and regulations and relevant to the sector. Additionally, this research presents guidelines for the sector of automotive batteries enterprises installed in Brazil that concern the opportunities and challenges for the adoption of GSCM practices / Mestre

Made available in DSpace on 2018-08-01T21:58:48Z (GMT). No. of bitstreams: 1 tese_10827_Dissertação Jenifer Rigo Almeida - FINAL.pdf: 2105933 bytes, checksum: 17fccc5751be81765e75282388ce4b0c (MD5) Previous issue date: 2017-03-27 / Baterias de íon-Lítio (LIBs) exauridas são consideradas resíduos sólidos perigosos devido à presença de metais e compostos orgânicos em sua composição, representando desperdício de recursos naturais não renováveis e de metais valiosos quando descartadas. Este trabalho tem por objetivo fornecer dados quantitativos sobre a composição química do material ativo do cátodo (MAC) de diferentes LIBs exauridas visando monitorar variações com o passar dos anos e auxiliar nos processos de reciclagem do material. Os elementos Al, Co, Cr, Cu, Ga, Li, Mg, Mn, Ni, Ti e Zn foram determinados por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) após lixiviação ácida empregando 2,0 mol.L-1 de ácido cítrico (HCit) e H2O2 (0,25 mol.L-1) como alternativa ambientalmente favorável. As condições otimizadas para adequação do meio às curvas analíticas foram: para Al, Cu: Curva de HCit diluído 10 vezes sem padrão interno (PI); para Co, Li, Mn, Ni: Curva de HCit diluído 500 vezes sem PI; para Ga, Zn: Curva de HCit diluído 10 vezes com Y. O procedimento analítico empregado alcançou limites de detecção de 0,01 mg.L-1 para Al; 0,20 mg.L-1 para Co; 0,006 mg.L-1 para Cr; 0,02 mg.L-1 para Cu; 0,004 mg.L-1 para Ga; 0,02 mg.L-1 para Li; 0,0005 mg.L-1 para Mg; 0,07 mg.L-1 para Mn; 0,70 mg.L-1 para Ni; 0,0005 mg.L-1 para Ti e 0,007 mg.L-1 para Zn. A exatidão do procedimento foi confirmada por testes de adição e recuperação dos analitos obtendo-se valores entre 92-113 %. Os elementos majoritários Co (43-67 % m/m), Li (5,3-6,8 % m/m), Mn (0,8-8,2 % m/m), Ni (0,1-11,7 % m/m) e Al (0,06-3,2 % m/m) e os elementos minoritários Cr (0,0005-0,002 % m/m), Cu (0,01-0,05 % m/m), Mg (0,005-0,02 % m/m), Ti (0,001-0,07 % m/m), Ga (0,0009-0,03 % m/m) e Zn (0,009-0,05 % m/m) demonstraram que a composição do MAC pode variar de acordo com a capacidade e ano de fabricação. As baterias mais antigas foram as que apresentaram maiores teores de Co e Li. As baterias de menor capacidade foram as que continham os maiores teores de Mn e Ni, indicando que o Co foi substituído. O pó do MAC e o resíduo após lixiviação foram caracterizados por difratometria de raios X (DRX) obtendo-se LiCoO2 como composto principal, podendo ser reutilizado.

In today’s world, we have reached the point where conventional energy forms are inevitably running out. At the same time, the technology for alternative energy harnessing is improving with big steps, especially with society rethinking their high consumption of finite energy and material. This opens the opportunity und increases acceptance for projects and research to prove its actual implementation and to push the boundaries of current technology further.One particular area of application is the automotive sector showcasing raise of costs due to depleting fuel. Solar powered cars are raising interest as it could be a way to complete independence of any resource that has to be produced, mined or in any way transported to the place of consumption. Involvement with the view to enhance their research in this field has become interesting for universities.With solar powered cars, new problems emerge, amongst others the amount of harnessed sun power and the storage to have it available at the point of use. Due to the low energy available, energy storage as light and as efficient as possible is needed. A system is required that allows to be operated independently of its surrounding in a way it is controllable.Lithium-ion based batteries were seen as the most applicable way to execute this, as they give the highest energy density with lower losses than stable, commercially available energy storage mediums.It was decided to design, build and integrate a battery system with its safety circuit into a solar car. After material selection suppliers were searched and contacted. With the successful manufacturing of this system combining different processing methods, partially at university and partially in the industry, the project included a monitoring and management system and protective measures. It was implemented so that neither the limitations of the chemistry and the physical cells nor the vibration occurring while driving the car prevents its proper use. Besides this, communication and dimensions to operate within the car followed, allowing the driver and convoy to access information and control the system.This battery system proved to be practical in street use comparable with that of regular cars and posed as a safe and effective energy supply for an electrically driven car, meeting the given demands.

Les batteries lithium-ion s'affichent comme de bons candidats pour assurer le stockage réversible de l'énergie électrique sous forme électrochimique. Toutefois, elles sont à l'origine d'un certain nombre d'incidents aux conséquences plus ou moins dramatiques. Ces incidents sont souvent liés au phénomène d'emballement thermique. La sécurité des batteries Li-ion représente par conséquent un enjeu technique et sociétal très important. C'est dans ce contexte que vient s'inscrire ce travail de thèse dans le cadre d'une collaboration entre IFPEN, l'INERIS et le LISE. Une double approche de modélisation et expérimentation a été retenue. Un modèle 3D du comportement thermique a été développé à l'échelle de la cellule, couplant les phénomènes thermiques et chimiques, et prenant en compte le vieillissement par croissance de la SEI sur l'électrode négative. Le modèle a été calibré pour la chimie LFP/C sur deux technologies A123s (2,3 Ah) et LifeBatt (15 Ah), puis validé expérimentalement. Le modèle permet d'identifier les paramètres critiques d'emballement de cellules, il permet également de discuter l'effet du vieillissement sur l'emballement thermique. Grâce à l'expérimentation, les connaissances en termes d'amorçage et de déroulement d'un emballement thermique d'une batterie Li-ion, ont pu être enrichies, en particulier pour les cellules commerciales LFP/C cylindriques A123s, LifeBatt, et pour les cellules NMC/C prismatiques en sachet souple PurePower (30 Ah). Cette étude ouvre de nouvelles possibilités pour améliorer la prédiction des différents événements qui ont lieu lors de l'emballement thermique des batteries Li-ion, à différentes échelles. / Li-ion secondary batteries are currently the preferred solution to store energy since a decade for stationary applications or electrical traction. However, because of their safety issues, Li-ion batteries are still considered as a critical part. Thermal runaway has been identified as a major concern with Li-ion battery safety. In this context, IFPEN, INERIS and LISE launched a collaboration to promote a PhD thesis so called « understanding and modeling of thermal runaway events pertaining to new and aged Li-ion batteries ». To achieve this goal, a double approach with modeling and experimental investigation is used. A 3D thermal runaway model is developed at cell level, coupling thermal and chemical phenomena, and taking into account the growth of the SEI layer as main ageing mechanism on negative electrode. Advanced knowledge of cells thermal behavior in over-heated conditions is obtained particularly for commercial LFP / C cylindrical cells: A123s (2,3Ah), LifeBatt (15Ah), and NMC / C pouch cells: PurePower (30 Ah). The model was calibrated for LFP / C cells, and then it was validated with thermal abuse tests on A123s and LifeBatt cells. This model is helpful to study the influence of cell geometry, external conditions, and even ageing on the thermal runaway initiation and propagation. This study opens up new possibilities for improving the prediction of various events taking place during Li-ion batteries thermal runaway, at various scales for further practical applications for safety management of LIBs.

Polymer electrolyte membrane fuel cell (PEMFC) stacks require sealing around the perimeter of the cells to prevent the gases inside the cell from leaking. Elastomeric materials are commonly used for this purpose. The overall performance and durability of the fuel cell is heavily dependent on the long-term stability of the gasket. In this study, the degradation of three elastomeric gasket materials (silicone rubber, commercial EPDM and a developed EPDM 2 compound) in an accelerated ageing environment was investigated. The change in properties and structure of a silicone rubber gasket caused by use in a real fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. Three accelerated ageing media were used. The first one was dilute sulphuric acid solution with the pH values of 1, 2 and 4. Secondly, Nafion® membrane suspended in water was used for accelerated ageing at a pH 3 to 4. Finally, diluted trifluoroacetic acid (TFA) solution of pH 3.3 was chosen. Weight change and the tensile properties of the aged gasket samples were measured. In addition, compression set behaviour of the elastomeric seal materials was investigated in order to evaluate their potential sealing performance in PEM fuel cells. The results showed that acid hydrolysis was the most likely mechanism of silicone rubber degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. The effect of TFA solution on silicone rubber was more aggressive than sulphuric acid and Nafion® solutions with the same acidity (pH value) suggesting that TFA accelerated the acid hydrolysis of silicone rubber. In addition, acid ageing in all three acidic solutions caused visible surface damage and a significant decrease in tensile strength of the silicone rubber material, but did not significantly affect the EPDM materials. EPDM 2 compound had a desirable (low) compression set value which was similar to silicone rubber and much better than the commercial EPDM. It also showed a very good performance in the fuel cell test rig conforming that it a potential replacement for silicone rubber in PEMFCs.