Thèses sur le sujet « Oxide Based Electrolytes »

The thesis details studies relating to polymer electrolytes; the solid ionic conductors farmed by the dissolution of salts in suitable high molecular weight polymers. An outline of polymer electrolyte study is presented with respect to current understanding of the phase behaviour, morphology and conductance behaviour of the electrolyte materials. (In particular, those based upon the linear homopolymer poly(ethylene oxide), PEO.) An electrochemical study has been undertaken (298 K) involving a low molecular weight PEO analogue, PEO(400)e = CH3C02(CH2CH20) CO CH3 (n = 8 - 9 ), containing LiCF3SO3 or LiClO4. The study has shown that at low to medium salt concentrations in polyether media ion - ion interactions are important and are realized as ion association. The conductance vs. concentration behaviour has been modelled according to an equilibrium between single, ion pair and triple ion species where the concentration of simple (single) ions are small and decreasing, and above a total salt concentration of about 0.01 mol kg−1, the majority of the current is carried by triple ion species of the form Li2X- LiX2 (X = CF3SO3 , CIO4). Equilibrium constant data were obtained for single and triple ion formation (from neutral ion pairs). Determination of triple ion formation constants vs. temperature has shown that the triple ion formation process for LiCF3SO3 in PEO(400)e is an exothermic process, negative, whereas for LiClO4 AH = 0 kJinal−1. Using nuclear magnetic resonance (nmr), diffusion coefficients have been obtained for the oligomer chain in PEO(400)e and PEO(400)e.LiCF3SO3 solutions. The chain diffusion coefficients have been shown to give good agreement with those for salt diffusion, determined from conductance measurements via the Nernst - Einstein relation. An in - depth nmr investigation of the PEO.LICF3SO3 system (high molecular weight PEO) has shown that there is partition of lithium environments, probably within the salt rich crystalline phase (EQ/Li - 3.5/1). Significant numbers of lithium nuclei are not observed with the nmr technique because they occupy environments of law symmetry. This was reinforced by other nmr measurements which suggested cation - anion proximity in the crystalline phase. A mixed salt system has been studied, PEO. LiCF3SO3. Nal, and it has been shown that the mixing of salts gave materials with superior conductivities to the relevant single salt systems (PEO. LiCF3SO3 and PEO.Nal) of the same overall salt content. Nmr has shown that the mixed salt effect was due to a larger amorphous (conducting) polymer phase and more potential charge carriers for the mixed salt in comparison to the single salt materials. A marked effect upon lithium motion was observed for PEO.LiCF3SO3 Nal system in comparison to PEO.LiCF3SO3 and it has been proposed that this was due to the observed lithium species becoming mobile at notably lower temperatures for the mixed salt system.

The main objective of this thesis was to explore, characterize and evaluate different CeO2-based electrolyte materials that could be employed to replace the existing yttria-stabilized zirconia oxide used as the electrolyte component of intermediate temperature solid oxide fuel cells (SOFCs). The electrolyte materials were synthesized using a radio frequency inductively coupled plasma reactor. CeO2-based fine powders doped with different compositions of Gd, Sm or Y were synthesized from nitrate salts dissolved in water. The powders were analyzed using X-ray diffraction, inductively coupled plasma (ICP), SEM and EDS (energy dispersive spectroscopy). It was demonstrated that the concentrations of Ce and dopants fed in the solutions were retained in the synthesized powders. The products were all crystalline and had multimodal size distributions. The effect of plasma synthesis parameters, i.e. plasma power, reactor pressure, and plasma flow rate on particle size distribution was studied. This analysis provides fundamental understanding of the mechanism of particle formation and collection in thermal plasma environments.

Scandia and ceria stabilized zirconia (10 mol% Sc2O3 – 1 mol% CeO2 – ZrO2, SCSZ) has superior ionic conductivity in the intermediate temperature range for the operation of solid oxide fuel cells, but it does not exhibit good phase stability in comparison with yttria stabilized zirconia (8 mol% Y2O3 – ZrO2, YSZ). To maintain high ionic conductivity and improve the stability of the electrolyte, layered structures with YSZ outer layers and SCSZ inner layers were designed, along with the referential electrolytes containing pure SCSZ or YSZ. The electrolytes were manufactured by tape casting, laminating, and pressureless sintering techniques. After sintering, while the thickness of YSZ outer layers remained constant at ~30 ?m, the thickness of inner layers of SCSZ for the 3-, 4- and 6-layer designs varied at ~30, ~60 and ~120 ?m, respectively. Selected characterizations were employed to study the structure, morphology, impurity content and the density of the electrolytes. Furthermore, in situ X-ray diffraction, neutron diffraction and Raman scattering were carried out to study the phase transition and lattice distortion during long-term annealing at 350 °C and 275 °C for SCSZ and YSZ, respectively, where the dynamic damping occurred when Young's modulus was measured. In YSZ/SCSZ electrolytes, thermal residual stresses and strains were generated due to the mismatch of coefficients of thermal expansion from each layer of different compositions. They could be adjusted by varying the thickness ratios of each layer in different designs of laminates. The theoretical residual stresses have been calculated for different thickness ratios. The effect of thermal residual stress on the biaxial flexural strength was studied in layered electrolytes. The biaxial flexure tests of electrolytes with various layered designs were performed using a ring-on-ring method at both room temperature and 800 °C. The maximum principal stress during fracture indicated an increase of flexural strength in the electrolytes with layered structure at both temperatures in comparison with the electrolytes without compositional gradient. Such an increase of strength is the result of the existence of residual compressive stresses in the outer YSZ layer. In addition, Weibull statistics of the strength values were built for the layered electrolytes tested at room temperature, and the effect of thermal residual stresses on Weibull distribution was established. The calculation of residual stress present at the outer layers was verified. The high ionic conductivity was maintained with layered electrolyte designs in the intermediate temperature range. It was also established that the ionic conductivity of layered electrolytes exhibited 7% – 11% improvement at 800 °C due to the stress/strain effects, and the largest improvements in a certain electrolyte was found to nearly coincide with the largest residual compressive strain in the outer YSZ layer. In addition to the study of layered electrolytes, mechanical properties of porous Ni/SCSZ cermet were studied. The anode materials were reduced by 65 wt% NiO – 35 wt% SCSZ (N65) and 50 wt% NiO – 50 wt% SCSZ (N50) porous ceramics in the forming gas. Young's modulus as well as strength and fracture toughness of non-reduced and reduced anodes has been measured, both at room and high temperatures. High temperature experiments were performed in the reducing environment of forming gas. It was shown that while at 700 °C and 800 °C the anode specimens exhibited purely brittle deformation, a brittle-to-ductile transition occurred at 800 – 900 °C, and the anode deformed plastically at 900 °C. Fractography of the anode specimens were studied to identify the fracture modes of the anodes tested at different temperatures.
Ph.D.
Doctorate
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

The need of substituting the current energetic model by a system based on clean Renewable Energy Sources (RES) have gained more importance in the last decades due to the environmental issues related to the use of fossil fuels. These energy sources are site-specific and intermittent, what makes essential the development of Energy Storage Systems (ESS) that allows the storage of the electricity generated by renewable energies. Among the technologies under development for the storage of electrical energy, Solid Oxide Electrolysis Cells (SOECs) have been proposed in the last decades as a promising technology. Achieving efficiencies higher than 85%, SOEC technology is able to convert electrical energy into chemical energy through the reduction of H2O, CO2 or the combination of both; generating H2, CO or syngas (H2 +CO). The implementation of this technology based on renewable electrical energy, combined with fuel cells would allow closing the carbon cycle. The work presented in this thesis has been devoted to enhance the performance of SOEC. The approach that is presented for that propose is based on the implementation of high surface area and thermally stable mesoporous metal oxide materials on the fabrication of SOEC electrodes. High performance and stability of the electrodes was expected during its characterization. Structural and electrochemical characterization techniques have been applied during the development of this thesis for this purpose. The thesis is organized in eight chapters briefly described in the following: Chapter 1 briefly analyses the current energy scenario presenting electrolysers as a promising technology for the storage of electrical energy. Besides, basic principles of SOECs operation and the state-of-the-art materials of SOECs are reviewed. Chapter 2 describes all the experimental methods and techniques employed in this thesis for the synthesis and characterization of synthesised materials and fabricated cells. Chapter 3 presents the results obtained from the structural characterization of the mesoporous materials and fabricated electrodes, revealing the successful implantation of the hard-template method for obtaining Sm0.2Ce0.8O1.9 (SDC), Ce0.8Gd0.2O1.9 (CGO) and NiO mesoporous powders, and the fabrication of SDC-SSC (Sm0.5Sr0.5CoO3-δ), CGO- LSCF (La0.6Sr0.4Co0.2Fe0.8O3) and NiO-SDC electrodes based on mesoporous materials. The attachment of the mesoporous scaffold for the fabrication of oxygen electrodes has been optimized at 900 °C. Chapter 4 compares electrolyte- and fuel electrode-supported cell configurations based on the same oxygen electrode. The electrochemical performance and the microstructural characterization of these cells are considered for that purpose. Showing a maximum current density of -0.83 and -0.81 A/cm2 on electrolysis and co- electrolysis modes respectively, fuel electrode-supported cells are considered more suitable for SOEC fabrication. Chapter 5 presents a study focused on analysing the influence of the oxygen electrode interface on the SOEC performance. The electrochemical and microstructural characterization of barrier layers and oxygen electrodes fabricated applying different methods are discussed in this chapter. The combination of a barrier layer fabricated by Pulsed Laser Deposition (PLD) with an oxygen electrode based on mesoporous materials resulted on the injection of up to -1 A/cm2, what allows concluding that this interface microstructure is directed related with the best performing SOECs in this thesis. Chapter 6 shows the performance of SOEC cells on co-electrolysis mode containing the optimized oxygen electrode, fabricated by infiltration of mesoporous scaffolds. The long-term stability of infiltrated mesoporous composites have been demonstrated during 1400 h, registering degradation rates of 2%/kh and <1%/kh when current densities of -0.5 A/cm2 and -0.75 A/cm2 are injected, respectively. Chapter 7 shows results of the scale-up of the mesoporous-based electrodes for the fabrication of large area cells. Their electrochemical performance shows high fuel flexibility, injecting -0.82 A/cm2 on co-electrolysis mode; and long-term stability injecting -0.5 A/cm2 for 600 h. The conclusions of this thesis are presented in Chapter 8.
Una de las principales desventajas de las fuentes de energías renovables es que producen energía eléctrica de forma discontinua. Los electrolizadores de alta temperatura basados en óxidos sólidos (SOEC) se presentan como una tecnología prometedora para el almacenamiento de energía eléctrica. Alcanzando eficiencias mayores de un 85%, los electrolizadores SOEC permite convertir energía eléctrica en energía química mediante la reducción de las moléculas de agua (H2O), dióxido de carbono (CO2), o la combinación de ambas; generándose hidrógeno (H2), monóxido de carbono (CO) o gas de síntesis (H2 +CO) como producto. El trabajo que se presenta en esta tesis tiene como objetico mejorar el rendimiento de los electrolizadores SOEC mediante la utilización de óxidos metálicos mesoporosos, caracterizados por poseer alta área superficial y ser estables a altas temperaturas. Esta tesis está organizada en ocho capítulos. Los capítulos 3, 4, 5, 6 y 7 presentan los resultados alcanzados: El capítulo 3 presenta la caracterización estructural de los materiales mesoporosos y de los electrodos fabricados. Además, la temperatura de adhesión del material mesoporoso ha sido optimizada y se ha fijado a 900 °C. El capítulo 4 compara electrolizadores fabricados soportados por el electrodo de combustible y por el electrolito. Los resultados muestran que las densidades de corriente más altas fueron inyectadas en los electrolizadores soportados por el electrodo de combustible, considerándose esta configuración la más apropiada. El capítulo 5 presenta la influencia de la microstructura de la intercara del electrodo de oxígeno en el rendimiento de los electrolizadores SOEC. La caracterización electroquímica, apoyada por la caracterización microestructural, ha demostrado que la máxima densidad de corriente ha sido inyectada por el electrolizador cuya barrera de difusión ha sido depositado por láser pulsado (PLD) y la capa funcional del electrodo de oxígeno mediante infiltración de materiales mesoporosos. El capítulo 6 estudia el electrodo de oxígeno optimizado. Durante 1400 h de operación continua y caracterización microstructural, se ha demostrado la estabilidad de este electrodo. Por último, el capítulo 7 muestra los resultados obtenidos del escalado de los electrodos mesoporosos en celdas de mayor área (25 cm2). La caracterización electroquímica muestra alta flexibilidad ante las composiciones de gases utilizadas, y estabilidad de los electrodos mesoporosos propuestos.

Cette thèse a pour but de caractériser le fonctionnement de supercondensateurs asymétriques composés de dioxyde de manganèse de structure birnessite et de carbone activé dans différents électrolytes. Les électrolytes aqueux neutres à base de sels inorganiques montrent les meilleures performances électrochimiques. La nature et la structure des cations et des anions du sel semblent impacter les performances électrochimiques et la stabilité de la structure du matériau d’oxyde de manganèse. Lors de cyclage en milieu aqueux avec de large de fenêtre de tension de fonctionnement appliquée, un mécanisme de dégradation du dispositif a été avancé tenant compte de la nature des anions ou des cations des sels utilisés. Quelques voies de modification du matériau MnO2, afin d’améliorer ces performances électrochimiques, ont été étudiés. Des électrolytes non aqueux originaux ont été également caractérisés et plus particulièrement, les solvants « Deep Eutectic » à base de N-méthylacétamide et de sels de Lithium. Ces derniers semblent prometteurs comme électrolytes pour des applications en température sur carbone activé ou matériaux d’insertion tels que le ferrophosphate de lithium. Cependant ils semblent non adaptés aux oxydes de manganèse, mais donnent de bons résultats en cyclage avec le carbone activé
The aim of this thesis was to investigate the performances of asymmetric supercapacitors based on manganese dioxide (birnessite) and activated carbon electrode materials using various electrolytes. From this work, it appears that neutral aqueous electrolytes containing inorganic salts have the best electrochemical performances. Furthermore, the nature and the structure of both ions (cations and anions) in solution seem to impact strongly the electrochemical performances of the supercapacitors, as well as, the MnO2’s structure stability and affinity. In the case of aqueous-based electrolyte, a device degradation mechanism has been proposed as a function of salt ions structure and nature to further understand the supercapacitor’s life-cycling when a large potential window is applied. Some novel synthesis ways and/or modifications were investigated to further improve the electrochemical properties of MnO2 material. Additionaly, original non-aqueous electrolytes has been also formulated and then characterized, particularly the ‘Deep Eutectic’ Solvents, based on the N-methylacetamide mixed with a lithium salt. However, these electrolytes don’t have a good affinity with manganese oxide-based materials. Interestingly, these Deep Eutectic Solvents show good cycling results with activated carbon. In fact, these electrolytes seem to be promising for high temperature energy storage applications, especially using activated carbon or insertion electrode material like the lithium ferrophosphate

Solid oxide fuel cells (SOFCs) have attracted much attention because of their potential of providing an efficient, environmentally benign, and fuel-flexible power generation system for both small power units and for large scale power plants. However, conventional SOFCs with yttria-stabilized zirconia (YSZ) electrolyte require high operation temperature (800-1000°C), which presents material degradation problems, as well as other technological complications and economic obstacles. Therefore, numerous efforts have been made to lower the operating temperature of SOFCs. The discovery of new electrolytes for low-temperature SOFCs (LTSOFCs) is a grand challenge for the SOFC community.

 Nanostructured materials have attracted great interest for many different applications, due to their unusual or enhanced properties compared with bulk materials. As an example of enhanced property of nanomaterials, the enhancement of ionic conductivity in the nanostructured solid conductors, known as “nanoionics”, recently become one of the hottest fields of research related to nanomaterials, since they can be used in advanced energy conversion and storage applications, such as SOFC. So in this thesis, we are aiming at developing a novel nanocomposite approach to design and fabricate ceria-based composite electrolytes for LTSOFC. We studied two ceria-based nanocomposite systems with different SDC morphologies.

 In the first part of the thesis, novel core-shell SDC/amorphous Na₂CO₃ nanocomposite was fabricated for the first time. The core-shell nanocomposite particles are smaller than 100 nm with amorphous Na₂CO₃ shell of 4~6 nm in thickness. The nanocomposite electrolyte shows superionic conductivity above 300 °C, where the conductivity reaches over 0.1 S cm-1. The thermal stability of such nanocomposite has also been studied based on careful XRD, BET, SEM and TGA characterization after annealing samples at various temperatures, which indicated that the SDC/Na₂CO₃ nanocomposite possesses better thermal stability on nanostructure than pure SDC. Such nanocomposite was applied in LTSOFCs with an excellent performance of 0.8 W cm-2 at 550 °C. The high performances together with notable thermal stability make the SDC/Na₂CO₃ nanocomposite as a potential electrolyte material for long-term SOFCs that operate at 500-600 °C.

In the second part of the thesis, we report a novel chemical synthetic route for the synthesis of samarium doped ceria (SDC) nanowires by homogeneous precipitation of lanthanide citrate complex in aqueous solutions as precursor followed by calcination. The method is template-, surfactant-free and can produce large quantities at low costs. To stabilize these SDC nanowires at high operation temperature, we employed the concept of “nanocomposite” by adding a secondary phase of Na₂CO₃, as inclusion which effectively hindered the grain growth of nanostructures. The SDC nanowires/Na2CO3 composite was compacted and sintered together with electrode materials, and was then tested for SOFCs performance. It is demonstrated that SOFCs using such SDC nanowires/Na₂CO₃ composite as electrolyte exhibited better performance compared with state-of-the-art SOFCs using conventional bulk ceria-based materials as electrolytes.

Steam electrolysis using a solid oxide electrolysis cell at elevated temperatures might offer a solution to high electrical energy consumption associated with conventional water electrolysers through a combination of favourable thermodynamics and kinetics. Although the solid oxide electrolysis cell has not. received significant attention over the past several decades and is yet to be commercialised, there has been an increased interest towards such a technology in recent years, aimed at reducing the cost of electrolytic hydrogen. Here, a one-dimensional dynamic model of a planar cathode-supported intermediate temperature solid oxide electrolysis cell stack has' been developed to investigate the potential for hydrogen production using such an electrolyser. Steady state simulations have indicated that the electrical energy consumption of the modelled stack is significantly lower than those of water electrolysers commercially available today. However, the dependence of stack temperature on the operating point has suggested that there is a need for temperature control. Analysis of a possible temperature control strategy by variation of the air flow rate through the stack has shown that the resulting changes in the convective heat transfer between the air flow and stack can alter the stack temperature. Furthermore, simulated transient responses indicated that manipulation of such an air flow rate can reduce stack temperature excursions during dynamic operation, suggesting that the p,oposed control strategy. has a good potential to prevent issues related to the stack temperature fluctuations.

The paper describes investigation on new types of supercapacitors based on composite polyani-line/reduced graphene oxide with network nanocomposite polymer electrolyte. Its prototypes are all solid state. The new network polymer electrolytes based on polyethylene glycol diacrylate and nanoparticle SiO2 was synthesized by reaction of radical polymerization in the environment of liquid organic electrolyte. The work is aimed to obtain a polymer electrolyte that is compatible with the electrode materials of superca-pacitors. For these purposes the method of FTIR spectroscopy, a.c. electrochemical impedance and gal-vanostatic cycling were used. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35510

Fast oxide-ion and proton conductors are the subject of considerable research due to their technological applications in sensors, ceramic membranes and solid oxide fuel cells (SOFCs). This thesis describes the use of computer modelling techniques to study point defects, dopants and clustering effects in fluorite-and perovskitetype ion conductors with potential SOFC applications. Bi2O3 related phases are being developed with the objective of high oxide-ion conductivities at lower operating temperatures than 1000°C, as in current generation SOFC electrolytes. Doped Bi2O3 phases have shown promise as materials capable of accomplishing this goal. First, the Y-doped phase, Bi3YO6, has been investigated including the ordering of intrinsic vacancies. The defect and dopant characteristics of Bi3YO6 have been examined and show that a highly mobile oxygen sub-lattice exists in this material. A preliminary structural modelling study of a new Re-doped Bi2O3 phase was also undertaken. A comprehensive investigation of the proton-conducting perovskites BaZrO3, BaPrO3 and BaThO3 is then presented. Our results suggest that intrinsic atomic disorder in BaZrO3 and BaThO3 is unlikely, but reduction of Pr4+ in BaPrO3 is favourable. The water incorporation energy is found to be less exothermic for BaZrO3 than for BaPrO3 and BaThO3, but in all cases the results suggest that the proton concentration would decrease with increasing temperature, in accord with experimental data. The high binding energies for all the dopant-OH pair clusters in BaPrO3 and BaThO3 suggest strong proton trapping effects. Finally, a study of multiferroic BiFeO3 is presented, in which the defect, dopant and migration properties of this highly topical phase are investigated. The reduction process involving the formation of oxygen vacancies and Fe2+ is the most favourable redox process. In addition, the results suggest that oxide-ion migration is anisotropic within this system.

Thesis (M.S.Ch.E.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science degree in Chemical Engineering." Bibliography: leaves 72-77.

Negli ultimi decenni è stata dedicata una grande attenzione alle tecnologie che utilizzano fonti di energia rinnovabili. Ciò è dovuto alla maggiore consapevolezza riguardo alle emissioni di gas serra e ai limiti della disponibilità e affidabilità future dei sistemi basati su fonti fossili. L'energia rinnovabile può essere considerata come gratuita, semi-infinita e pulita; tuttavia, alcuni svantaggi devono essere tenuti in considerazione. La necessitá di adempiere ala domanda istantanea di elettricità e all'utilizzo come carburante per i trasporti rappresentano alcune delle piú importanti sfide che devono essere affrontate dalle fonti di energia rinnovabili. L'energia solare ed eolica, ad esempio, sono caratterizzate da una forte variabilità, che le rende incapaci di soddisfare istantaneamente la domanda di energia. Pertanto risulta fondamentale l’integrazione di un accumulo di energia per gestire il bilancio tra domanda e produzione. Il presente studio è dedicato alla progettazione e all'analisi di un sistema integrato per la produzione di combustibili sintetici come mezzo per l’accumulo di energia generata attraverso fonti rinnovabili. Il sistema proposto integra un elettrolizzatore ad ossidi solidi, un gassificatore a letto trascinato e la sintesi di Fischer-Tropsch. Il principale prodotto del sistema è il diesel di sintesi via Fischer-Tropsch, prodotto da vapore, CO2 e diverse risorse rinnovabili, ossia biomassa lignocellulosica ed elettricità generata da sistemi fotovoltaici ed eolici. Questo approccio presenta il vantaggio di accumulare, sotto forma di energia chimica dei combustibili idrocarburici, l'energia elettrica in eccesso proveniente dalle tecnologie a fonti rinnovabili, per un ulteriore utilizzo durante le ore di picco della domanda di energia. Inoltre, l'utilizzo di questi combustibili sintetici si traduce in un aumento della quota di energia da fonti rinnovabili nel sistema di trasporto. Nello stesso tempo vengono sfruttate tecnologie di distribuzione e conversione esistenti che presentano ancora buone efficienze operative. Il sistema proposto viene analizzato da diversi punti di vista, quali quello termodinamico, economico e ambientale. Questo studio include diversi aspetti della ricerca contemporanea, dalla ricerca della condizione operativa ottimale dei sottosistemi per produzione di syngas alla valutazione del potenziale teorico di sistemi integrati in diverse località.

Le premier objectif de cette thèse est l’étude de l’influence de charges inorganiques (additifs) sur les propriétés des électrolytes polymères composites, à base de poly(oxyde d’éthylène) de basses et hautes masses moléculaires. Pour étudier tout les facteurs, nous avons choisi trois oxydes d’aluminium et deux oxydes de titane, distincts de par la taille des grains. Il apparaît exclusivement que les échantillons d’oxyde d’aluminium aux grains de taille micrométrique sont clairement modifiés ; les particules d’oxyde d’aluminium sont plus sensibles au traitement que les oxyde de titane et l’effet est plus marqué pour les particules de taille micrométriques par rapport aux particules nanométriques d’oxyde d’aluminium. Ensuite les poudres (au total 26) étaient utilisées comme charge pour les électrolytes polymères à base de dimétoxy-poly(oxyde d’éthylène) de masse moléculaire moyenne 500 g•mol-1 (liquide à température ambiante) et le poly(oxyde d'éthylène de masse moléculaire moyenne 5•102g•mol-1(solide à température ambiante). Le perchlorate de lithium (LiClO4) a été à chaque fois utilisé comme sel et sa concentration fixée à de 1 mol•kg-1. En résumé – des électrolytes contenant un large panel de poudres ont été étudiés, et il a été montré que les conditions de préparation des électrolytes avec les mêmes matériaux de départ peuvent conduire à l’obtention de matériaux finaux différents. Cela peut expliquer les divergences entre les résultats rapportés dans la littérature ces dernières années. Enfin, l’influence des poudres sur la conductivité et les conditions de son augmentation ont été déterminées
The primary goal of this work was to study the influence of surface-modified inorganic fillers on the properties of composite polymeric electrolytes based on poly(oxyethylene) of both low and high molecular weight. To study all interesting factors we chose three different aluminas and two titanias characterised by different grain sizes. It appeared that only microsized aluminas are readily modified. Less sensitive to the treatment is nano alumina and the least are titanias. Then obtained powders (26 in total) were applied as fillers for polymeric electrolytes based on poly(oxyethylene) of molecular weight aqual to 500 g•mol-1 (liquid at room temperature) and 5•106 g•mol-1 (liquid at room temperature) and 5•106 g•mol-1(solid at room temperature). Lithium perchlorate was used as a salt, its concentration was fixed to be 1 mol•kg-1. In general, a vast population of samples was prepared and it was shown that starting with the same material, one can obtain totally different products. That can explain many of the discrepancies found in the literature published on this subject over the last 20 years. Apart from that a universal procedure of samples preparation was established and conditions of conductivity improvement determined

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:97/00727-3

Esistono attualmente varie ragioni per cui ampio interesse scientifico e tecnologico è rivolto verso sistemi di generazione di energia alternativi rispetto ai metodi convenzionali (quali i sistemi a turbine o i motori a combustione interna). Dal punto di vista ecologico, cresce il bisogno di ridurre la produzione di sostanze inquinanti per far fronte a uno sviluppo sostenibile. Da un punto di vista socio-economico, invece, aumenta il bisogno di far fronte a un continuo aumento della richiesta di energia, mentre nello stesso tempo le principali fonti di energia, quali i combustibili fossili, si stanno esaurendo. E infine, da un punto di vista socio-politico, la scarsità delle attuali fonti di energia sta creando drammatiche tensioni tra le varie aree economiche del mondo. La diminuzione della dipendenza mondiale dai combustibili fossili e l’introduzione di forme di generazione di energia alternative potrebbero sanare tale situazione. Il concetto di energia alternativa è stato introdotto già da vari anni. Ci sono diverse fonti d energia alternativa, come l’energia solare, l’energia eolica o la fusione nucleare. Un diverso approccio consiste nello sviluppo di sistemi di generazione di energia alternativi, che siano in grado di lavorare con alti rendimenti e di limitare al massimo la produzione di inquinanti. Allo stato attuale i motori a combustione interna presentano un’efficienza totale del 20-30%. Questo significa che solo il 20-30% dell’energia termica contenuta nel gasolio viene utilizzata come lavoro meccanico. Alti rendimenti si traducono, invece, in costi ridotti per unità di lavoro prodotto. Le celle a combustibile sono sistemi di conversione di energia alternativi i quali permettono la conversione diretta dell’energia chimica dei reagenti in energia elettrica, producendo al contempo basse emissioni inquinanti. Tra i diversi tipi di celle a combustibile, le celle a ossidi solidi (SOFCs) presentano vari vantaggi; tra i primi, lavorando ad alta temperatura (800-100°C) queste celle raggiungono valori di rendimento molto alti, permettono l’uso di diversi combustibili e l’unica emissione inquinante rilevante è quella di CO2, la quale rimane comunque un terzo di quella emessa da un motore a combustione interna a parità di kW/h prodotti. Tuttavia le alte temperature di lavoro comportano anche degli svantaggi: materiali costosi, elevati stress termici, difficoltà nel sigillare la cella, lunghi tempi di accensione e spegnimento del sistema. Per risolvere questi problemi la ricerca è orientata nell’abbassare la temperatura di funzionamento delle SOFCs nel cosiddetto range di temperature intermedie (400-700°C). Abbassare la temperatura di funzionamento si traduce in un peggioramento delle performance dei vari componenti della cella, e per questo lo studio di nuovi materiali risulta essenziale nella prospettiva di rendere le SOFC commercializzabili. Lo scopo di tale lavoro di tesi è appunto lo studio di materiali elettrolitici ed elettrodici che presentino buone proprietà conduttive a temperature di funzionamento intermedie e che allo stesso tempo siano chimicamente stabili. Nel capitolo 1A della tesi si presentano i principi basilari di funzionamento di una SOFC e una breve illustrazione dei materiali più studiati in letteratura sia per le alte e intermedie temperature di funzionamento. In particolare, tra i materiali ceramici con buone proprietà conduttive a basse temperature si trovano i conduttori protonici. Nel Capitolo 2A vengono illustrate le principali proprietà chimico-fisiche ed elettrochimiche di tali materiali ceramici. Molti ossidi perovskitici presentano conduzione protonica a temperature intermedie quando esposti ad atmosfera di idrogeno e/o vapore acqueo. Tuttavia nessuno di questi ossidi presenta contemporaneamente le due proprietà essenziali richieste ad un buon elettrolita: alta conducibilità ionica e buona stabilità chimica. La seconda parte della tesi presenta i risultati del lavoro sperimentale svolto, il quale è stato rivolto alla preparazione e caratterizzazione di conduttori protonici ceramici elettrolitici con alta conducibilità e buona stabilità chimica e allo sviluppo di elettrodi a - hoc per tali elettroliti. Il Capitolo 1B riporta l’ottimizzazione di una tecnica di sintesi sol gel per produrre i seguenti conduttori protonici: BaZr0.8Y0.2O3-δ (BZY) e BaCe0.8Y0.2O3-δ (BCY). Attraverso il metodo di sintesi ottimizzato si sono sintetizzate fasi singole dei suddetti composti. Le basse temperature di calcinazione richieste dal processo hanno portato a polveri di particelle nanometriche. I due composti sono stati sinterizzati in forma di pasticche circolari e caratterizzati elettricamente mediante spettroscopia di impedenza. Inoltre sono stati svolti test termici in flusso di anidride carbonica per valutare la stabilità chimica dei due composti, osservando una buona stabilità solo nel caso del BZY. Tuttavia le performance in cella di tale elettrolita si sono rilevate insufficienti rispetto ai target richiesti per la commercializzazione. Nel Capitolo 2B si è cercato di implementare le prestazioni del BZY sostituendo nel sito B della struttura perovskitica diverse quantità di Ce. Gli elettroliti cosi prodotti sono stati analizzati ai raggi X, sotto il punto di vista della stabilità chimica e della conducibilità elettrica. Il miglior compromesso tra stabilità chimica e conducibilità elettrica è risultato il composto con stechiometria BaZr0.5Ce0.3Y0.2O3-δ. Un ulteriore miglioramento della conduzione elettrica rispetto al BaZr0.5Ce0.3Y0.2O3-δ, pur mantenendo un’ottima stabilità chimica, è stato ottenuto realizzando un elettrolita “a doppio strato”, il quale è descritto nel Capitolo 3B. Una pasticca spessa 1 mm di BCY è stata protetta con uno strato sottile (circa un micron) di BZY cresciuto tramite la tecnica di deposizione a laser pulsato. Questo nuovo elettrolita ha presentato elevata conducibilità e buone prestazioni in cella in termini di stabilità chimica e densità potenza fornita. Nel Capitolo 4B si sono invece investigati elettrodi funzionali per tali elettroliti a conduzione protonica. Un catodo composito e stato realizzato unendo un conduttore misto ionico/elettronico, La1-xSrxCo1-yFeyO3-δ (LSCF), e un conduttore misto protonico/elettronico BaCe0.9Yb0.1O3-δ (10YbBC). L’uso di catodi compositi aumenta i siti di reazione al catodo, diminuendo quindi le cadute di potenziale dovute alle reazioni catodiche.
There are increasing reasons to explore alternatives to conventional energy generation methods (that is to say coal-fired steam turbine and gasoline internal combustion engine). From an ecological point of view, there is the need to reduce the polluting by-products of conventional energy generation. From a socio-economical standpoint, the worldwide demand for energy continues to rise as more and more nations join the group of the industrialized countries, while hydrocarbon fuels go to exhaustion. Finally, from a socio-political perspective, the situation described above has created several and often dramatic tensions between different world economic areas, as evidenced by frequent wars. Lowering the global dependence on oil might reduce such tensions. However, despite all of this, changes in the energy generation methods are extremely slow, as evidenced by the wide (if we cannot say total) use of the internal combustion engine. The concept of alternative energy has been introduced a long time ago. Several different sources of energy are proposed, which can have the potential to replace conventional generation methods. Popular examples include solar radiation, wind motion, and nuclear fusion. Each of these technologies has its own set of problems that have slowed down its commercialization, but much research is being conducted to overcome these problems. In fact, the research towards the development of alternative, highly efficient, eco-friendly energy production technologies is expanding. There is a general push towards higher efficiencies. At present, automobiles based on internal combustion engines have an overall efficiency of about 20-30%. That is, only 20-30% of the thermal energy content of the gasoline is converted into useful mechanical work and the rest is wasted. Higher efficiencies translate into reduced energy costs per unit of work done. Fuel cells, an alternative energy technology, have received growing interest in recent years since they represent one of the most promising energy production systems to reduce pollutant emissions. They are electrochemical devices that allow the direct conversion of chemical energy into electrical energy. Among the different type of fuel cells, solid oxide fuel cells (SOFCs) offer great promise as a clean and efficient technology for energy generation and provide significant environmental benefits. They produce negligible hydrocarbons, CO or NOx emissions, and, as a result of their high efficiency, about one-third less CO2 per kW/h than internal combustion engines. Unfortunately, the current SOFC technology based on a stabilized zirconia electrolyte requires the cell to operate from 700 to 1000°C to avoid unacceptable ohmic losses. These high operating temperatures demand specialized (expensive) materials for fuel cell interconnectors, long start-up time, and large energy input to heat the cell up to the operating temperature. Therefore, if fuel cells could be designed to give a reasonable power output at intermediate temperatures (IT, 400-700°C), tremendous benefits may result. In particular, in the IT range ferrite steel interconnects can be used instead of expensive and brittle ceramic materials. In addition, sealing becomes easier and more reliable; rapid start-up is possible; thermal stresses (namely, those caused by thermal expansion mismatches) are reduced; electrode sintering becomes negligible. Combined together, all these improvements result in reduced initial and operating costs. Therefore, the major trend in the present research activities on SOFCs is the reduction of the operating temperature. The problem is that lowering the operating temperatures lowers the electrolyte conductivity, whereas the electrode polarization greatly increases, reducing the overall fuel cell performance. Considering the described scenario, it is clear how the study of materials assumes a considerable role in lowering SOFC operating temperature. Making SOFCs commercially competitive with conventional energy generation methods means developing a highly efficient and environmental friendly energy production device to provide for a global sustainable energy system. IT-SOFCs represent not only a laboratory research activity, but a great challenge for the entire society. The purpose of the present dissertation is the development of a stable highly-conductive electrolyte and performing electrodes for lower temperature SOFCs. Chapter 1A presents the physico-chemical principles of SOFCs functioning, the demands imposed on the components materials, together with a literature survey on the state of-the art technology. Starting from more “conventional” oxygen ion conducting electrolytes, the need for reducing the operation temperature leads to a discussion on the properties of proton conducting materials as a feasible alternative to reach the goal of fabricating an IT-SOFCs. Chapter 2A describes the main properties of ceramic proton conductors. Several perovskite-type oxides, such as doped BaCeO3, SrCeO3, BaZrO3, and SrZrO3, show proton conductivity in the IT range when exposed to hydrogen and/or water vapour containing atmospheres. They are generally known as high temperature proton conductors (HTPCs). The main challenge in the field of HTPC is to find a compound that concurrently satisfies two of the essential requirements for fuel cell application, namely high proton conductivity and good chemical stability under fuel cell operating conditions. The second part of this dissertation describes the experimental results achieved during the research carried out. In view of the considerations given in Chapter 2a, Chapter 1B describes the optimization of the sol-gel procedure to prepare BaZr0.8Y0.2O3-δ (BZY) proton conductor electrolyte. Producing BZY powders with controlled compositional homogeneity and microstructure using a proper synthesis method could improve the electrochemical performance of this electrolyte. The optimized sol–gel procedure allowed the reduction of the diffusion path up to a nanometric scale, and thus required lower calcination temperatures. Nanocrystalline single-phase powders of BZY were produced at temperatures as low as 1100 °C. The same sol-gel procedure was also used to synthesize BaCe0.8Y0.2O3-δ (BCY) proton conductor electrolyte achieving also in this case nanometric particles powder at the calcination temperature of 100°C. The performance of the synthesized BZY and BCY proton conductors were examined in terms of chemical stability. After exposure to CO2 at high temperatures, the synthesized BZY powders presented good chemical and microstructural stability, differently from BCY which strongly decomposed after the CO2 treatment. Electrical conductivity and fuel cell performance were investigated only for the stable BZY electrolyte, however without achieving the required performance for practical application. Chapter 2 presents the application of the optimized synthetic procedure to the preparation of different proton conductor electrolytes. To further improve the electrochemical performance of barium zirconate electrolyte, the B-site of the BZY perovskite structure was doped with Ce producing several BaZr0.8-xCexY0.2O3-δ compounds (0.0≤x≤0.8). The prepared samples were analyzed in terms of chemical stability in CO2 environment, electrical conductivity, microstructural characteristics, and finally under fuel cell tests. Among the tested electrolytes, the BaZr0.5Ce0.3Y0.2O3-δ composition represented the best compromise between electrical performance and chemical stability. In fact it was able to maintain almost the same chemical stability of BZY, but with improved, more than twice, fuel cell performance. Chapter 3 describes a further improvement of the HTPC electrolyte performance. To obtain a highly conductive and chemically stable proton conductor electrolyte, a sintered Y-doped barium cerate (BCY) pellet was protected with a thin BZY layer, grown by pulsed laser deposition. The overall performance of the bilayer electrolyte turned out to be of great interest for practical use in IT-SOFCs application. The promising performance of this bilayer electrolyte rose from the very good crystallographic matching at the interface between the two materials, as well as the microstructure properties of the protecting layer in terms of uniformity, density and filling factor. However, while the bilayer conductivity was only slightly smaller than the conductivity of the BCY pellet, the measured fuel cell performances were negatively affected by the interface of the Pt electrodes with the BZY layer. For this reason the development of a superior cathode is crucial to make IT-SOFCs based on proton conductors competitive with the more established SOFCs using oxygen-ion conductor electrolytes. Chapter 4 focuses on the optimization of composite cathodes for application in IT-SOFC based on HTCP electrolytes. To explore different cathode materials with respect to the most commonly used for proton conductor electrolytes, such as platinum or cobalto-ferrites, the area specific resistance (ASR) of composite cathodes was investigated. Firstly, BaCe0.9Yb0.1O3-δ (10YbBC) and SrCe0.9Yb0.1O3-δ (10YbSC) were tested as cathode materials since they show mixed protonic-electronic conductivity. However, the ASR of the interface of these cathode materials with Y-doped barium cerate proton conductor electrolyte was extremely large, probably because of their too low partial electronic conductivity. For this reason, La1-xSrxCo1-yFeyO3-δ (LSCF), which presents high electronic conductivity, was combined with 10YbSC or 10YbBC to form composite cathodes. LSCF was chosen also because it allows faster oxygen surface exchange being a mixed O2-/e- conductor. The lowest ASR values were achieved with the composite cathode made of LSCF and 10YbBC in a1:1 ratio. Single phase Pt and LSCF cathodes were tested and it was found that they showed higher interfacial resistance than LSCF/10YbBC(1:1) composite cathode. This finding clearly suggests the importance of the proton conductor phase within the electrode, which actually should increase the triple phase boundary (TPB) density and so improve the cathode performance. The good performance observed for LSCF/10YbBC(1:1) composite cathode make it a cheaper and more efficient alternative to the Pt cathode that can actually improve the performance of IT-SOFCs based on proton conductor electrolytes.

Oxygen is used for a wide range of applications, with a globally projected production capacity of 1.8 million tonne per day in 2020. Depending on the economic range and the required purity, various methods are used to extract oxygen. Conventionally, cryogenic air separation is used for the large to medium production scale, characterised by high purity oxygen and relatively low energy consumption, whilst pressure swing adsorption (PSA) is widely used for the small-scale production, with lower oxygen purity and higher energy consumption. A high-efficiency system for high purity oxygen production based on the integration of solid oxide- fuel and electrolysis cells (SOFC and SOEC) was first proposed by Iora and Chiesa in 2009. However, the lack of a detailed methodology and the novelty of such a system necessitated a system-level energy analysis with an emphasis on the SOFC and SOEC to understand the nature of thermal and electrical coupling between them. Here, the initial feasibility of the system has been evaluated considering the lumped-parameter modelling of the SOFC, SOEC and balance of plant. A system energy consumption that is significantly less than that of PSA systems was predicted, and a significant contribution of the stack energy consumption to the overall system energy consumption was observed, suggesting the need for a thorough examination of the electrochemical models. Therefore, the parameter estimation technique has been implemented to validate the electrochemical models based on a 5-cell stack and a single repeating unit SOEC experimental data. A good agreement was obtained between the experimental and model-predicted cell potential across all operating conditions, and key electrochemical parameters were estimated with confidence. The validated electrochemical model has then been integrated into a newly-developed onedimensional model of a planar SOFC-SOEC stack to further improve the predictions of the stack and system performance. Significant contributions of experimental validation and distributed modelling on enhancing the predictions of the stack model were observed. The advantages of the system over PSA systems in terms of energy efficiency and oxygen purity were confirmed. A potential design point of the system was selected via a techno-economic study, revealing an extremely low contribution of the electricity cost to the total cost of production. An adequate thermal integration at both the stack and system levels were demonstrated at the design point.

Le développement des dispositifs microélectroniques a dopé la recherche dans le domaine des microbatteries tout solide rechargeables. Mais actuellement, les performances de ces microbatteries élaborées par des technologies couche mince (2D) sont limitées et le passage à une géométrie 3D adoptant le concept “Li-ion” ou“rocking chair” est incontournable. Cette dernière condition implique de combiner des matériaux de cathode comme LiCoO2, LiMn2O4 or LiFePO4 avec des anodes pouvant réagir de manière réversible avec les ions lithium. Parmi tous les matériaux pouvant servir potentiellement d'anode, les nanotubes de TiO2 révèlent des propriétés intéressantes pour concevoir des microbatteries Li-ion 3D. Facilement réalisable, la nano-architecture auto-organisée a montré des résultats très prometteurs en termes de capacités à des cinétiques relativement modérées. L'utilisation des nanotubes de TiO2 en tant qu'anode conduit à des cellules présentant de faible autodéchargeet élimine le risque de surcharge grâce au haut potentiel de fonctionnement (1.72 V vs. Li+/Li). Dans ce travail de thèse, nous avons étudié la substitution des ions Ti4+ par Sn4+ et Fe2+ dans les nanotubes de TiO2. Bien que la présence d'ions Fe2+ n'ait pas amélioré les performances électrochimiques des nanotubes, nous avons pu mettre en évidence l'effet bénéfique des ions Sn4+. Nous avons aussi pu montré que la fabrication de matériaux composites à base de nanotubes de TiO2 et d'oxyde de métaux de transition électrodéposés se présentant sous forme de particules (NiO et Co3O4 ) augmentait les capacités d'un facteur 4
The advent of modern microelectronic devices has necessitated the search for high-performance all-solid-state (rechargeable) microbatteries. So far, only lithium-based systems fulfill the voltage and energy density requirements of microbatteries. Presently, there is a need to move from 2D to 3D configurations, and also a necessity to adopt the “Li-ion” or the “rocking-chair” concept in designing these lithium-based (thin-film) microbatteries. This implies the combination of cathode materials such as LiCoO2, LiMn2O4 or LiFePO4 with the wide range of possible anode materials that can react reversibly with lithium. Among all the potential anode materials, TiO2 nanotubes possess a spectacular characteristic for designing 3D Li-ion microbatteries. Besides the self-organized nano-architecture, TiO2 is non-toxic and inexpensive, and the nanotubes have been demonstrated to exhibit very good capacity retention particularly at moderate kinetic rates. The use of TiO2 as anode provides cells with low self-discharge and eliminates the risk of overcharging due to its higher operating voltage (ca. 1.72 V vs. Li+/Li). Moreover, their overall performance can be improved. Hence, TiO2 nanotubes and their derivatives were synthesized and characterized, and their electrochemical behaviour versus lithium was evaluated in lithium test cells. As a first step towards the fabrication of a 3D microbattery based on TiO2 nanotubes, electrodeposition of polymer electrolytes into the synthesized TiO2 nanotubes was also studied; the inter-phase morphology and the electrochemical behaviour of the resulting material were studied

Le mécanisme élémentaire de l'électrodépôt de films de MnO2 fût étudié sur des électrodes de Pt massif dans des électrolytes aqueux. Il se révèle être une réaction multi-étapes sensible au pH et à la force ionique. La chronoampérométrie couplée à des électrolytes neutres peu concentrés favorise l'électrodépôt de films stables de MnO2. Le FTO est un meilleur substrat que l'ITO parce qu'il présente une activité électrochimique plus élevée et favorise la stabilité mécanique de films électrodéposés de MnO2. De plus, le potentiel d'électrodépôt influence à la fois la structure et la morphologie des films de MnO2. Les films amorphes de MnO2 obtenus à potentiel élevé possèdent une activité électrocatalytique et une stabilité plus élevées que la birnessite. Un traitement thermique peut améliorer amplement leur activité électrocatalytique et leur stabilité mécanique. Une transition de phase des films de MnO2 apparaît à 500 °C. Leur morphologie change de façon dramatique après chauffage au-delà de cette température. Les échantillons chauffés à 500 °C ont la meilleure activité électrocatalytique pour l'OER. Les cations Na+, K+, Ca2+ and Mg2+ sont insérés en petites quantités dans la structure des films de MnO2 au cours de la démarche d'électrodépôt, mais ils influencent néanmoins la structure et la morphologie des films. Finalement, les films de birnessite ou amorphes apparaissent comme des candidats prometteurs en tant que catalyseurs pour la dissociation photoélectrochimique de la dissociation de l'eau, puisqu'ils génèrent des photocourants considérables sous lumière solaire. Pour cela, des films de MnO2 épais, amorphes et recuits à 500 °C produisent les meilleures performances
The basic electrodeposition mechanism of MnO2 films was studied first on bulk Pt electrodes in various aqueous electrolytes. It was revealed that MnO2 electrodeposition is a multi-step reaction that is sensitive to pH and ionic strength. Chronoamperometry coupled to low concentration neutral aqueous solutions favors the electrodeposition of stable MnO2 films. FTO was found to be a better substrate than ITO, because it has a higher electrochemical activity and could enhance the mechanical stability of electrodeposited MnO2 films. Moreover, the potential used for electrodeposition has great influence on both the structure and the morphology of MnO2 films. Amorphous MnO2 films obtained at high potential possess higher electrocatalytic activity and stability than the birnessite-type MnO2 variety. The heat treatment can greatly enhance the electrocatalytic activity and mechanical stability. A phase transition of MnO2 films appears at 500 °C. The morphology changes dramatically after heating above this temperature. Samples heated at 500 °C are found to have the best electrocatalytic activity towards OER. Na+, K+, Ca2+ and Mg2+ cations were found to be inserted in small amounts into the structure of MnO2 films during the electrodeposition procedure but they influence the structure and morphology of the films. Finally, birnessite type and amorphous MnO2 films appear to be promising candidates as catalysts for photoelectrochemical water splitting, as they are able to generate considerable photocurrents under solar light illumination. In this purpose, thick and amorphous films with 500 °C heat treatment are supposed to produce the best performances

In this thesis, the focus is on studying BaZrO3-BaCeO3 based proton conductors due to that they represent very promising proton conductors to be used for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs). Here, dense BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) ceramics were selected as the major studied materials. These ceramics were prepared by different sintering methods and doping strategies. Based on achieved results, the thesis work can simply be divided into the following parts: 1) An improved synthesis method, which included a water-based milling procedure followed by a freeze-drying post-processing, was presented. A lowered calcination and sintering temperature for a Hf0.7Y0.3O2-δ (YSH) compound was achieved. The value of the relative density in this work was higher than previously reported data. It is also concluded that this improved method can be used for mass-production of ceramics. 2) As the solid-state reactive sintering (SSRS) represent a cost-effective sintering method, the sintering behaviors of proton conductors BaZrxCe0.8-xLn0.2O3-δ (x = 0.8, 0.5, 0.1; Ln = Y, Sm, Gd, Dy) during the SSRS process were investigated. According to the obtained results, it was found that the sintering temperature will decrease, when the Ce content increases from 0 (BZCLn802) to 0.3 (BZCLn532) and 0.7 (BZCLn172). Moreover, the radii of the dopant ions similar to the radii of Zr4+ or Ce4+ ions show a better sinterability. This means that it is possible to obtain dense ceramics at a lower temperature. Moreover, the conductivities of dense BZCLn532 ceramics were determined. The conductivity data indicate that dense BZCY532 ceramics are good candidates as either oxygen ion conductors or proton conductors used for ITSOFCs. 3) The effect of NiO on the sintering behaviors, morphologies and conductivities of BZCY532 based electrolytes were systematically investigated. According to the achieved results, it can be concluded that the dense BZCY532B ceramics (NiO was added during ball-milling before a powder mixture calcination) show an enhanced oxygen and proton conductivity. Also, that BZCY532A (NiO was added after a powder mixture calcination) and BZCY532N (No NiO was added in the whole preparation procedures) showed lower values. In addition, dense BZCY532B and BZCY532N ceramics showed only small electronic conductivities, when the testing temperature was lower than 800 ℃. However, the BZCY532A ceramics revealed an obvious electronic conduction, when they were tested in the range of 600 ℃ to 800 ℃. Therefore, it is preferable to add the NiO powder during the BZCY532 powder preparation, which can lower the sintering temperature and also increase the conductivity. 4) Dense BZCY532 ceramics were successfully prepared by using the Spark Plasma Sintering (SPS) method at a temperature of 1350 ℃ with a holding time of 5 min. It was found that a lower sintering temperature (< 1400 ℃) and a very fast cooling rate (> 200 ℃/min) are two key parameters to prepare dense BZCY532 ceramics. These results confirm that the SPS technique represents a feasible and cost-effective sintering method to prepare dense Ce-containing BaZrO3-BaCeO3 based proton conductors. 5) Finally, a preliminary study for preparation of Ce0.8Sm0.2O2-δ (SDC) and BZCY532 basedcomposite electrolytes was carried out. The novel SDC-BZCY532 based composite electrolytes were prepared by using the powder mixing and co-sintering method. The sintering behaviors, morphologies and ionic conductivities of the composite electrolytes were investigated. The obtained results show that the composite electrolyte with a composition of 60SDC-40BZCY532 has the highest conductivity. In contrast, the composite electrolyte with a composition of 40SDC-60BZCY532 shows the lowest conductivity. In summary, the results show that BaZrO3-BaCeO3 based proton-conducting ceramic materials represent very promising materials for future ITSOFCs electrolyte applications.

QC 20150423

Energy storage devices are generally evaluated on two main requirements; power and energy. In supercapacitors these two performance criteria are altered by the capacitance, resistance and voltage. (For complete abstract open document)

Le développement de catalyseurs de la réaction de dégagement de l’oxygène (OER) pour les électrolyseurs à membrane échangeuse de protons (PEM) dépend de la compréhension du mécanisme de cette réaction. Cette thèse est consacrée à l'application de la spectroscopie d’émission de photoélectrons induits par rayons X (XPS) et de la spectroscopie de structure près du front d'absorption de rayons X (NEXAFS) operando sous une pression proche de l'ambiante (NAP) dans le but d’étudier les mécanismes de la réaction d’oxydation de l’eau sur des anodes à base d’iridium et de ruthénium et leurs dégradation dans les conditions de la réaction. Cette thèse montre les mécanismes différents de la réaction OER pour les anodes à base d’Ir et de Ru impliquant respectivement des transitions anioniques (formation d’espèce OI- électrophile) ou cationiques (formation des espèces de Ru avec l’état d'oxydation supérieur à IV) quelle que soit la nature (thermique ou électrochimique) des oxydes
Development of oxygen evolution reaction (OER) catalysts for proton exchange membrane water electrolysis technology depends on the understanding of the OER mechanism. This thesis is devoted to the application of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and near edge X-ray absorption fine structure (NEXAFS) techniques for operando investigation of the Ir, Ru - based anodes. For Ru-based systems, we observe the potential-induced irreversible transition of Ru (IV) from an anhydrous to a hydrated form, while the former is stabilized in the presence of Ir. Regarding single Ir-based anodes, the analysis of O K edge spectra reveals formation of electrophilic oxygen OI- as an OER intermediate. Higher stability of Ir catalysts supported on antimony-doped tin oxide (ATO) is related to their lower oxidation. This work demonstrates different OER mechanisms on Ir, Ru-based anodes involving anion and cation red-ox chemistry, correspondingly, regardless the oxide nature

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:03/07331-0

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Os catalisadores eletroquímicos binários de PtSn/C, PdSn/C e PtPd/C foram sintetizados em diferentes proporções pelo método da redução via borohidreto, posteriormente estes foram caracterizados por microscopia eletrônica de transmissão, difração de raios X, espectroscopia no infravermelho por transformada de Fourier (PtSn/C e PdSn/C) e energia dispersiva de raios X. As atividades eletroquímicas dos diferentes materiais preparados foram avaliadas por intermédio de voltametria cíclica, cronoamperometria e curvas de polarização em célula a combustível alimentada diretamente por etileno glicol em eletrólito alcalino. As curvas de densidade de potência indicaram que os catalisadores eletroquímicos contendo Sn e Pd são mais ativos para a reação de oxidação do etileno glicol, especialmente a composição 70%:30% - relação molar entre os metais suportados em carbono - dos catalisadores PtSn/C, PdSn/C e PtPd/C todos superando as medidas de potência do Pt/C. Este resultado indica que a adição de Sn e Pd favorece a oxidação do etileno glicol em meio alcalino. O melhor desempenho observado para os catalisadores eletroquímicos PtSn/C, PdSn/C e PtPd/C (70%:30%) poderia estar associado à sua maior seletividade quanto a formação de oxalato, ou seja , a formação deste produto resulta em um maior número de elétrons, por consequência em maiores valores de corrente.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Fuel cells are electrochemical devices that convert chemical energy in electrical energy by a reaction directly. The solid oxide fuel cell (SOFC) works in temperature between 900?C up to 1000?C, Nowadays the most material for ceramic electrolytes is yttria stabilized zirconium. However, the high operation temperature can produce problems as instability and incompatibility of materials, thermal degradation and high cost of the surround materials. These problems can be reduced with the development of intermediate temperature solid oxide fuel cell (IT-SOFC) that works at temperature range of 600?C to 800?C. Ceria doped gadolinium is one of the most promising materials for electrolytes IT-SOFC due high ionic conductivity and good compatibility with electrodes. The inhibition of grain growth has been investigated during the sintering to improve properties of electrolytes. Two-step sintering (TSS) is an interesting technical to inhibit this grain growth and consist at submit the sample at two stages of temperature. The first one stage aims to achieve the critical density in the initiating the sintering process, then the sample is submitted at the second stage where the temperature sufficient to continue the sintering without accelerate grain growth until to reach total densification. The goal of this work is to produce electrolytes of ceria doped gadolinium by two-step sintering. In this context were produced samples from micrometric and nanometric powders by two routes of two-step sintering. The samples were obtained with elevate relative density, higher than 90% using low energy that some works at the same area. The average grain size are at the range 0,37 μm up to 0,51 μm. The overall ionic conductivity is 1,8x10-2 S.cm and the activation energy is 0,76 eV. Results shown that is possible to obtain ceria-doped gadolinium samples by two-step sintering technique using modified routes with characteristics and properties necessary to apply as electrolytes of solid oxide fuel cell
As c?lulas a combust?vel s?o dispositivos eletroqu?micos que convertem energia qu?mica em energia el?trica por uma rea??o direta. As c?lulas a combust?veis de ?xido s?lidos (Solid Oxide Fuel Cell - SOFC) operam em temperaturas entre 900 e 1000?C, com eletr?litos de cer?mica. Atualmente o material mais utilizado ? a zirc?nia estabilizada com ?tria, no entanto a alta temperatura de opera??o pode causar problemas de instabilidade e incompatibilidade de materiais, degrada??o t?rmica e alto custo dos materiais perif?ricos. Com a inten??o de minimizar esses problemas, s?o realizadas pesquisas para desenvolver c?lulas a combust?vel de ?xido s?lido de temperatura intermedi?ria (IT-SOFC) que operam na faixa de temperatura de 600 a 800?C, utilizando c?ria dopada com gadol?nia como um dos mais promissores materiais para eletr?litos de IT-SOFC devido ? alta condutividade i?nica e uma boa compatibilidade com os eletrodos. Formas de inibir o crescimento do gr?o durante a sinteriza??o para melhorar as propriedades dos eletr?litos s?o investigadas. Para tal, ? utilizada a t?cnica de sinteriza??o em dois passo (two-step sintering - TSS), que consiste em submeter a amostra a dois est?gios de temperatura. O primeiro est?gio visa atingir a densidade cr?tica para dar in?cio ao processo de sinteriza??o. Em seguida a amostra ? submetida a um segundo est?gio de temperatura capaz de dar continuidade ? sinteriza??o sem que haja acelerado crescimento de gr?o, at? sua total densifica??o. O principal objetivo deste trabalho foi produzir eletr?litos de c?ria dopada com gadol?nia pelo processo de sinteriza??o em dois passos. Neste contexto foram produzidas amostras a partir de p?s microm?tricos e nanom?tricos atrav?s de duas rotas de sinteriza??o em dois passos. Foram obtidas amostras com elevada densidade relativa, superior a 90%. Os tamanhos m?dios de gr?os obtidos est?o na faixa de 0,37 μm a 0,51 μm. Foram obtidas amostras com condutividade i?nica total de 1,8x10-2 S.cm e energia de ativa??o de 0,76 eV. A partir dos resultados obtidos neste trabalho, foi poss?vel obter amostras de c?ria dopada com gadol?nia atrav?s da t?cnica de sinteriza??o em dois passos, utilizando rotas modificadas com caracter?sticas e propriedades necess?rias para serem aplicadas como eletr?litos de c?lulas a combust?vel de ?xido s?lido

Tendo como vantagem a elevada resistência ao choque térmico da zircônia:magnésia e a alta condutividade iônica da zircônia:ítria, compósitos dessas cerâmicas foram preparados por meio da mistura, em diferentes concentrações, de eletrólitos sólidos de ZrO2: 8,6 mol% MgO e de ZrO2: 3 mol% Y2O3, compactação e sinterização. A caracterização microestrutural foi feita por meio de difração de raios X e microscopia eletrônica de varredura. A análise do comportamento térmico foi feita por dilatometria. As propriedades elétricas foram estudadas por meio de espectroscopia de impedância. Foi feita uma montagem experimental para monitorar a resposta elétrica gerada em função do teor de oxigênio a altas temperaturas. Os principais resultados mostram que os compósitos cerâmicos são parcialmente estabilizados nas fases monoclínica, cúbica e tetragonal, e apresentam comportamento térmico similar ao apresentado por eletrólitos sólidos de zircônia:magnésia de dispositivos sensores de oxigênio. Além disso, os resultados de análise de espectroscopia de impedância mostram que a adição da zircônia:ítria melhora o comportamento elétrico da zircônia:magnésia, e que resposta elétrica gerada é dependente do teor de oxigênio a 1000 °C, mostrando ser possível construir sensores de oxigênio utilizando compósitos cerâmicos.
Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO2: 8.6 mol% MgO and ZrO2: 3mol% Y2O3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO2: 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 °C, showing that the ceramic composites can be used in oxygen sensors.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Ce travail de thèse est consacré à l’étude des nickelates La2-xPrxNiO4+δ, comme nouveaux matériauxde cathodes pour piles à combustible haute température, SOFC, et en particulier à la caractérisationde leur stabilité chimique et leur comportement en fonctionnement. En effet, du fait de leurpropriété de conduction mixte ionique et électronique, MIEC, les nickelates de structure typeK2NiF4, Ln2NiO4+δ (Ln = La, Pr, Nd), correspondant au terme n = 1 de la série de Ruddlesden-Popper (An+1MnO(3n+1)), sont des matériaux prometteurs pour des fonctionnements à températureintermédiaire, IT-SOFC (T < 800 °C). Compromis entre la stabilité chimique de La2NiO4+δ et lestrès bonnes performances électrochimiques de Pr2NiO4+δ, les phases La2-xPrxNiO4+δ, ont étésynthétisées et leurs propriétés physico-chimiques, de transport et électrochimiques ont étédéterminées. L’étude approfondie des caractéristiques des électrodes par spectroscopied’impédance en cellules symétriques a été réalisée à courant nul et sous polarisation anodique etcathodique sur des périodes d’un mois. De façon surprenante, même après la dissociation complètede Pr2NiO4+δ en PrNiO3-δ, Pr4Ni3O10+δ et Pr6O11, la résistance de polarisation ne montre pas dechangement significatif. L’étude de PrNiO3-δ et Pr4Ni3O10+δ, comme matériau de cathode pour pilesà combustible, démontre l’excellent comportement de la phase Pr4Ni3O10+δ et ceci en cellulesymétrique (Rp (Pr4Ni3O10+δ) = Rp (Pr2NiO4+δ) = 0.15 Ω.cm² à 600 ° C) et cellule complète (1.6W.cm-2 at 800 °C)
This PhD work is dedicated to stability and ageing studies of Praseodymium based nickelates ascathodes for Solid Oxide Fuel Cells (SOFCs). With this respect Ln2NiO4+δ (Ln=La, Pr or Nd)compounds with the K2NiF4 type structure act as alternative cathode materials for IT-SOFC due totheir mixed ionic and electronic conductivity (i.e. MIEC properties). Pr2NiO4+δ shows excellentelectrochemical properties at intermediate temperature (i.e. low polarization resistance Rp value, Rp= 0.03 Ω.cm² at 700 °C), while La2NiO4+δ exhibits higher chemical stability. So, the properties ofLa2-xPrxNiO4+δ nickelates were investigated with the aim to find best compromise between chemicalstability and electrochemical performances. After synthesis, the physical and chemical properties aswell as their transport and electrochemical properties have been determined. Measurements of thepolarization resistance of symmetrical half-cells have been carried out by impedance spectroscopy.Then, the chemical stability and the electrochemical performance of the materials have been studiedfor duration up to one month. As an interesting point, even after complete dissociation of Pr2NiO4+δinto PrNiO3-δ,Pr4Ni3O10+δ and Pr6O11, the polarization resistance does not show significant change.So finally, two new materials PrNiO3-δ and Pr4Ni3O10+δ were investigated as SOFCs cathodeshowing very promising results for Pr4Ni3O10+δ in symmetrical cell (Rp (Pr4Ni3O10+δ) = Rp(Pr2NiO4+δ) = 0.15 Ω.cm² à 600 ° C) and complete cell (1.6 W.cm-2 at 800 °C)

L’étude de l'électrocatalyse des réactions de réduction de l'oxygène (RRO) et de dégagement de l'oxygène (RDO) est étroitement reliée au développement de matériaux cathodiques et anodiques pour les piles à combustible et les électrolyseurs. L’objectif de cette thèse est de développer et d’étudier des matériaux d’électrodes à base d’oxydes de Mn et de Co, actifs et stables, à la fois pour la RRO et la RDO. Les relations entre les caractéristiques électrochimiques des compositions pérovskite / carbone et les propriétés de leurs composants sont établies et étayées expérimentalement dans la thèse. Il a été constaté que la résistance des matériaux carbonés à la corrosion dans les conditions de la RDO est influencée non seulement par leur ordre cristallin, mais également par leur activité intrinsèque pour la RDO. Il a été démontré que les activités des pérovskites à base de Mn et de Co dépendent linéairement du nombre de cations de Mn et de Co rechargeables, respectivement pour la RRO et la RDO. Il a été découvert qu'une intercalation réversible de l'oxygène dans la structure cristalline des pérovskites à base de Co se produit dans les conditions de la RDO, ainsi qu'à des potentiels plus faibles
A study of electrocatalysis of oxygen reduction (ORR) and oxygen evolution (OER) reactions is closely related with a development of cathodic and anodic materials for fuel cells and elec-trolyzers. An objective of this thesis is to develop and investigate Mn, Co-oxide-based elec-trode materials active and stable in both the ORR and OER. Relationships between electro-chemical characteristics of perovskite/carbon compositions and properties of their compo-nents are stated and experimentally substantiated in the thesis. It is found a corrosion re-sistance of carbon materials under OER conditions is influenced not only by their crystalline order, but also by their intrinsic OER activity. It is shown the ORR and OER activity of Mn, Co-based perovskites linearly depends on the number of rechargeable Mn and Co cations, respectively. It is revealed a reversible oxygen intercalation through a crystal structure of Co-based perovskites occurs under OER conditions as well as at lower potentials

碩士
國立臺北科技大學
材料科學與工程研究所
99
The IT-SOFC electrolytes, co-doped bismuth oxide based, were prepared by the solid state reaction. Due to the high oxide ionic conductivity of the bismuth oxide, it is a good material for application in SOFC electrolyte. The Bi0.76Y0.24-xGdxO1.5 (x=0.02~0.10), Bi0.76Y0.24-xNbxO1.5+δ (x=0.02~0.10), Bi0.76Y0.24-xScxO1.5 (x=0.02~0.10), Bi0.76Y0.24-xZr2xO1.5-δ (x=0.02~0.10) and Bi0.76Y0.24-xBa2xO1.5-δ (x=0.02~0.10) were prepared and sintered at 825oC~1025oC for 2 hours, respectively. The microstructure, crystal structure and ionic conductivity of the sintered specimens were analyzed by using SEM, XRD and DC resistance meters, respectively. The results show that most of the crystal structure of the sintered specimens are cubic.The best conductivity of these specimens is Bi0.76Y0.14Zrx0.10O1.5+δ with 1 S/cm at 800oC.

碩士
國立成功大學
化學工程學系
87
The composite electrolytes (CEs) were prepared by impregnating the ternary composites consisting polypropylene glycol based waterborne polyurethane (denoted as WPU(PPG)), polytetramethylene glycol based waterborne polyurethane (denote as WPU(PTMG), and polyethylene oxide (PEO) with LiClO4/PC. The data of the swollen weight (Sw) and the room temperature conductivity (25) for CEs were fitted as empirical regression equations by using mixture design. These empirical equations were used to construct contour plots, facilitating comparisons of synergistic/antagonistic effects among the mixed polymers. The contour plots show that the maximum Sw (64.3%) appears at point X3(PEO 95%, WPU(PPG) 5%), while the maximum 25 (~ 10-3 S cm-1) appears in a wide region (WPU(PPG)=5 ~ 43%, WPU(PTMG) < 37%, and PEO > 27%). Differential scanning calorimetry (DSC) results showed immiscibility between WPU(PTMG) and PEO and partial immiscibility between WPU(PPG) and WPU(PTMG)/PEO. Polarized microscope (PM) for ternary composites were also examined. The contour plot results of Sw and 25 can reasonably explained the interactions among polymers on the basis of their molecular structures, which are also evidenced by both DSC and PM results.

碩士
國立臺北科技大學
材料及資源工程系研究所
100
The purpose of this study was to develop apatite-type lanthanum germanate-based solid electrolytes for SOFC (Solid Oxide Fuel Cell). In order to achieve the best conductivity of the electrolyte materials applications, these ceramics were doped with various ions with larger ionic radii than that of Ge4+ ion and to substitute part of the ion Ge4+ in La9.5Ge6O25.25. Various dopants including Al2O3、MnO2、MoO3、TiO2、WO3、Ga2O3、Nb2O5、Fe2O3、NiO、SnO2 and MgCO3 were added into to La9.5□0.5(GeO4)6O2±y, respectively. These lanthanum germanate-based solid electrolyte powders were synthesized by solid state reaction. These specimens were sintered at various temperatures and periods of time, then the conductivity of the specimens were measured. The results showed that, sintering temperature is too high for achieve the desired densities by doping MnO2, secondary phase is formed by doping TiO2, the electrical conductivity is reduced significantly by doping NiO. Therefore, the three kinds of dopant were unfavorable used in the lanthanum germanate-based electrolytes. However, other doped specimens such as La9.5Ge5.5Al0.5O26, La9.5Ge5.5Mo0.5O26.75, La9.5Ge5.5W0.5O26.75, La9.5Ge5.5Fe0.5O26 and La9.5Ge5.5Nb0.5O26.5 have better conductivity, which are similar to that of 8YSZ measured at 800oC. Among them La9.5Ge5.5Nb0.5O26.5 possesses the best conductivity (0.045 S/cm) at 800oC.

碩士
中原大學
化學研究所
91
Polyacrylonitrile (PAN) was adding into various particle size and proportion of α-aluminum oxide to achieve a series of gel-type polymer electrolytes. The significances of the addition of inorganic nanoparticles into the polyacrylonitrile based gel polymer electrolyte was also studied. AC impedance was employed to exam the conductivity of composed gel polymer electrolyte, moreover, powder X-Ray, SEM, DMA, CV and battery testing system were all used to comparison the physical or chemical properties between neat polymer-based or composite-based electrolytes. The best result of conductivity of composite-based electrolyte was presented at particle size of 50 nm with 7wt% addition of α-Aluminum oxide in concentration of LiClO4, F=0.6 at 30℃. It is also realized the α-aluminum oxide were disperse evenly in the electrolyte shown by the SEM-EDX tests, and the addition of which was found to lower the softening point, shown by the DMA tests. Furthermore, it is confirmed by the battery test system that addition of α-aluminum oxide indeed enhance the ability of charge/discharge for the lithium coin cell.

碩士
國立成功大學
化學工程學系
87
Composite electrolytes (CEs) containing polyethylene oxide (PEO), polytetramethylene glycol based waterborne polyurethane(WPU(PTMG)), LiClO4/propylene carbonate (PC), and aluminum oxide (Al2O3) have been prepared by blending. The influences of the addition of Al2O3 in CEs were investigated by the following methods. Differential scanning calorimetry (DSC) and polarizing microscopy (PM) were employed for material characterization. The swollen weight of CEs was measured to appraise the maximum tolerating intake. Alternating current (AC) impedance was employed to obtain the ionic conductivity. Furthermore, Li/CE/LiCoO2 laminated cells were assembled to measure open-circuit voltages (Voc) for the application evaluation. Accordingly, the CE consisting of 20 % PEO, 20 % WPU(PTMG), 10 % Al2O3, and 50 % LiClO4/PC possesses the best performance for all investigated characteristics. Furthermore, the effects of co-solvent/co-salt were investigated by using mixture design.

碩士
國立臺灣科技大學
機械工程系
93
In order to develop an outstand electrolyte that owns high mechanical and electric properties and a metallic interconnect that exhibits better oxidation-resistance for Solid Oxide Fuel Cell (SOFC) application in intermittent operation at high temperature. The purpose of this thesis is to investigate the mechanical properties and toughness behavior of zirconia electrolyte. Besides, the electric properties and oxidative problem of metallic interconnect were discussed in this study. A systematic study involves mechanical properties measurements, phase-composition characteristics and microstural analysis were conducted by micro-indentation hardness testing, X-ray diffractometer, in-situ compression-diffraction using synchrotron radiation source and Raman scattering spectrum, respectively. The experimental results show that coexistence of two mechanisms, the ferroelastic domain switching and the stress-induced phase transformation were not observed in the YNbO4-modified ZrO2 (3Y) ceramics under stress loading at different levels. It is different from the results in the past literature. In the in-situ compression-diffraction experiment using synchrotron radiation, the results suggest there is a lattice adjustment of cubic phase occurred under stress loading. Besides the O2- and Zr4+ ions vibration varied under cyclic loading was observed using Raman scattering spectrum. The La0.7Sr0.3MnO3 (LSMO) layer was coated on stainless steels (SUS430 and SUS304) using Sol-gel method and radio frequency (RF) sputtering. The results exhibit the best annealing temperature is 800℃ and LSMO coating layer produces high conductivity of (Mn,Fe)Cr2O4 that is one thousand times the electric conductivity of Cr2O3 and decreases the content of Cr2O3, because of Mn3+ content increase. This seems that t’-to-m’ phase transformation and cubic phase to adjust itself might be the primary energy-absorbing mechanism in the ZrO2-based electrolyte and LSMO coating layer improves the oxidation-resistance of metallic interconnect for SOFC application.