Dans cette thèse, nous démontrons des travaux sur la synthèse à faible coût des matériaux de cathode et l'anode pour les piles lithium-ion. Pour les cathodes, nous avons utilisé des précurseurs à faible coût pour préparer LiFePO4 et LiFe0.3Mn0.7PO4 en utilisant une méthode hydrothermale. Tout d'abord, des matériaux composites (LiFePO4/C) ont été synthétisés à partir d'un précurseur de Fe2O3 par une procédé hydrothermique pour faire LiFePO4(OH) dans une première étape suivie d'une calcination rapide pour le revêtement de carbone. Deuxièmement, LiFePO4 avec une bonne cristallinité et une grande pureté a été synthétisé en une seule étape, avec Fe2O3 par voie hydrothermale. Troisièmement, LiFe0.3Mn0.7PO4 a été préparé en utilisant Fe2O3 et MnO comme des précurseurs de bas coûts au sein d'une méthode hydrothermale synthétique. Pour les matériaux d'anode, nous avons nos efforts concentré sur un matériau d'anode à faible coût α-Fe2O3 avec deux types de synthèse hydrothermales, une a base de micro-ondes (MAH) l’autre plus conventionnelles (CH). La nouveauté de cette thèse est que pour la première fois le LiFePO4 a été préparé par une méthode hydrothermale en utilisant un précurseur Fe3+ (Fe2O3). Le Fe2O3 est un précurseur à faible coût et en combinant ses coûts avec les conditions de synthèse à basse température nous avons réalisé une réduction considérable des coûts de production pour le LiFePO4, menant ainsi à une meilleure commercialisation du LiFePO4 comme matériaux de cathode dans les piles lithium-ion. Par cette méthode de préparation, le LiFePO4/C procure une capacité de décharge et une stabilité de cycle accrue par rapport une synthétisation par la méthode à l'état solide pour les mêmes précurseurs Les résultats sont résumés dans deux articles qui ont été récemment soumis dans des revues scientifiques. / In this thesis, low cost syntheses of cathode and anode materials for lithium ion batteries will be presented. For cathode materials, low cost precursors were used to prepare LiFePO4 and LiFe0.3Mn0.7PO4 using low temperature hydrothermal method. Initially, a LiFePO4/C composite material was synthesized from a Fe2O3 precursor using a hydrothermal method to prepare LiFePO4(OH) in a first step followed by a fast calcination and carbon coating. Secondly, LiFePO4 with good crystallinity and high purity was synthesized, in one step, with nanometric sized Fe2O3 by a hydrothermal method. Thirdly, LiFe0.3Mn0.7PO4 was prepared using low cost Fe2O3 and MnO as precursors within a hydrothermal synthetic method. For anode materials, a low cost anode material α-Fe2O3 was prepared using two hydrothermal synthetic methods, microwave assisted (MAH) and conventional hydrothermal (CH). The novelty of the thesis is for the first time LiFePO4 has been prepared using a low cost Fe3+ precursor (Fe2O3) by a hydrothermal method. Low cost precursors and low temperature synthesis conditions will greatly reduce the synthetic cost of LiFePO4, leading to greater commercialization of LiFePO4 as a cathode materials for lithium-ion batteries. The as-prepared LiFePO4/C product provided enhanced discharge capacity and cycling stability compared to that synthesized using a solid state method with the same precursors. The results were summarized within two articles that were recently submitted to peer reviewed scientific journals.

Dans cette thèse nous démontrons le travail fait sur deux matériaux de cathodes pour les piles lithium-ion. Dans la première partie, nous avons préparé du phosphate de fer lithié (LiFePO4) par deux méthodes de lithiation présentées dans la littérature qui utilisent du phosphate de fer (FePO4) amorphe comme précurseur. Pour les deux méthodes, le produit obtenu à chaque étape de la synthèse a été analysé par la spectroscopie Mössbauer ainsi que par diffraction des rayons X (DRX) pour mieux comprendre le mécanisme de la réaction. Les résultats de ces analyses ont été publiés dans Journal of Power Sources. Le deuxième matériau de cathode qui a été étudié est le silicate de fer lithié (Li2FeSiO4). Une nouvelle méthode de synthèse a été développée pour obtenir le silicate de fer lithié en utilisant des produits chimiques peu couteux ainsi que de l’équipement de laboratoire de base. Le matériau a été obtenu par une synthèse à l’état solide. Les performances électrochimiques ont été obtenues après une étape de broyage et un dépôt d’une couche de carbone. Un essai a été fait pour synthétiser une version substituée du silicate de fer lithié dans le but d’augmenter les performances électrochimiques de ce matériau. / In this thesis, we demonstrate work on two different cathode materials for lithium-ion batteries. First, the synthesis of lithium iron phosphate (LiFePO4) is reproduced from literature using two lithiation methods starting with amorphous iron phosphate (FePO4). For both reactions, the product at each step of the synthesis was analyzed using Mössbauer Spectroscopy and X-ray diffraction in order to gain further insight of the reaction mechanism. The results of this work were published in Journal of Power Sources. The second cathode material of interest was lithium iron silicate (Li2FeSiO4). A novel synthetic method was developed to produce lithium iron silicate cost effectively starting with low cost precursors and basic laboratory equipment. The material was synthesized using a solid- state synthesis after milling and carbon coating, electrochemical performance was evaluated. An attempt was made to synthesize off-stoichiometric lithium iron silicate in order to increase the electrochemical performance of the material.

Emerging energy storage applications are driving the demand for Li-ion battery positive electrode materials with higher energy densities and lower costs. The recent production of complete pseudo-ternary phase diagrams of the Li-Mn-Ni-O system generated using combinatorial methods has provided a greater understanding of the impact of initial composition, synthesis temperature, and cooling rate on the phases that form in the final materials. This thesis focuses on the synthesis and characterization of gram-scale positive electrode materials in the Li-Mn-Ni-O system. Structural analysis of these samples has resulted in the production of partial pseudo-ternary phase diagrams focusing on the positive electrode materials region of the Li-Mn-Ni-O system at 800°C and 900°C in air for both quenched and slow cooled compositions. These bulk-scale diagrams support the observations of the combinatorial diagrams, and show similar layered and cubic structures contained within several single- and multi-phase regions. The phases that form at each composition are shown to be dependent on both the reaction temperature and cooling rate used during synthesis. The electrochemical characterization of two composition series near Li2MnO3, one quenched and one slow cooled, is presented. The quenched compositions exhibited reversible cycling at 4.4 V, voltage plateaus and small increases in capacity above 4.6 V, and large first cycle irreversible capacity losses at 4.8 V. In the slow cooled series, all but one composition exhibited initial capacities below 100 mAh/g which began to continually increase with cycling, with several compositions exhibiting capacity increases of 300% over 150 cycles at 4.9 V. In both series, analysis of the voltage and differential capacity plots indicated that significant structure rearrangements are taking place in these materials during extended cycling, the possible origins of which are discussed. Finally, high precision coulometry studies of one Li-deficient and two Li-rich single-phase layered compositions are discussed. These materials exhibit minimal oxidation of simple carbonate-based electrolyte when cycled to high potential, with the Li-deficient composition producing less electrolyte oxidation at 4.6 V vs. Li/Li+ than commercial Li[Ni1/3Mn1/3Co1/3]O2 at 4.2 V. The inherent inertness of this composition may make it suitable for use as a thin protective layer in a core-shell particle.

Lithium‐ion batteries are particularly suitable as energy storage solutions in high power applications, such as hybrid electric vehicles. It is generally considered that one of the processes that limit the power density for lithium‐ion batteries is the mass transport in the electrolyte. Yet, it is still difficult to find a set of properties that fully describe the mass transport for the most common electrolytes. In this work, characterization studies of the mass transport were undertaken for two technically important lithium‐ion battery electrolytes: (1) a liquid electrolyte which consist of LiPF6 dissolved in ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and, (2) a gel electrolyte which consists of LiPF6 dissolved in ethylene carbonate, propylene carbonate (PC) and poly(vinylidenefluoride‐hexafluoropropylene) (P(VdFHFP)).The mass transport in the electrolytes was characterized by combining several experiments. The Maxwell‐Stefan equation was used as basis for the characterization. Models of the transport were formulated from the equation and the apparent transport properties were identified. The characterization methods were first analyzed mathematically in order to establish at which conditions the characterization experiments should be performed. The values of the apparent transport properties were then obtained by optimizing the models to the experimental responses. In order to give the characterization results a comprehensible interpretation and to allow benchmarking of electrolytes, the concept of a normalized potential gradient was introduced.The characterization results of the liquid electrolyte were used in a full cell model of a LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG‐10 cell. The model was developed to analyze the mass transport during a hybrid pulse power characterization (HPPC) test. The analysis was made with a method where the polarization was split up into parts each associated with a process within the cell. The optimum composition in terms of mass transport was found to lie between 0.5 and 1.2 mol/dm3 LiPF6 for the liquid electrolyte and between 5 and 7 wt. % LiPF6 for the gel electrolyte. Less amount of polymer in the gel electrolyte gave a faster mass transport. It was also found that the mass transport in the liquid electrolyte contributed to a major part of the polarization during HPPC tests. / Litiumjonbatterier är speciellt lämpliga som ackumulatorer i högeffektsapplikationer som elhybridfordon. Det är idag allmänt accepterat att en av processerna som begränsar effekttätheten för litiumjonbatterier är masstransporten i elektrolyten. Trots detta är det fortfarande svårt att få tag på data som fullständigt beskriver masstransporten i de vanligaste elektrolyterna. I det här arbetet har masstransportkarakteriseringar gjorts för två tekniskt viktiga elektrolyter: (1) en vätskeelektrolyt som består av LiPF6 upplöst i etylenkarbonat (EC) och etylmetylkarbonat (EMC), och (2) en gel elektrolyt som består av LiPF6 upplöst i EC, propylenkarbonat (PC) och poly(vinylidene fluoride‐hexafluoro propylene) (P(VdFHFP)). Masstransporten i elektrolyterna karakteriserades genom att kombinera ett antal karakteriseringsexperiment. Maxwell‐Stefans ekvation användes som utgångspunkt i karakteriseringarna. Modeller av transporten formulerades från ekvationen och de effektiva transportegenskaperna identifierades. En matematisk analys gjordes först av karakteriseringstekniken, så att det kunde fastslås för vilka förhållanden experimenten skulle utföras. Värderna av transportegenskaperna erhölls genom att optimera modellerna till det experimentella beteendet. För att ge karakteriseringsresultaten en begriplig tolkning och för att kunna mäta prestandan av elektrolyter, infördes konceptet normaliserad potentialgradient. Resultatet från karakteriseringen av vätskeelektrolyten användes i en model av en LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG‐10 cell. Modellen utvecklades för att analysera masstransporten i cellen under ett hybridpulstest (HPPC). Analysen gjordes med en metod där polarisationen delades upp i delar som var och en var kopplad till en process i batteriet. Den optimala sammansättningen med avseende på masstransporten låg i regionen 0.5–1.2 mol/dm3 LiPF6 för vätskeelektrolyten och 5‐7 vikt% LiPF6 för gelelektrolyten. Mindre mängd polymer i gelelektrolyten gav en snabbare masstransport. Det konstaterades också att masstransporten i vätskeelektrolyten bidrog med en av de största delarna till polarisationen i HPPC testen. / QC 20110128

Deux approches ont été considérées pour l’optimisation de matériaux lamellaires d’électrode positive pour batteries lithium-ion de type Li1+x(Ni1/2-yMn1/2-yCo2y)1-xO2 : la modification de surface (coating) et la substitution partielle. Dans un premier temps, nous avons montré que la substitution anionique du fluor à l’oxygène n’était pas effective contrairement aux hypothèses proposées dans la littérature par certains auteurs, mais qu’en réalité une couche de LiF était formée à la surface de ces matériaux, quelle que soit la voie de synthèse utilisée. Ces matériaux "coatés" présentent néanmoins une cyclabilité améliorée en batterie au lithium. Leurs propriétés structurales et physico-chimiques ont été caractérisées en combinant notamment la diffraction des rayons X, la spectroscopie RMN MAS du 7Li et du 19F et la spectroscopie d’électrons Auger. Dans un second temps, nous avons étudié l’effet de la substitution de l’aluminium (électrochimiquement inerte) au cobalt au sein de ces matériaux lamellaires riches en nickel et en manganèse. Les conditions de synthèse ont été optimisées et un matériau intéressant a ainsi été proposé. La structure, et plus particulièrement la distribution cationique, ont été déterminées par des analyses chimiques, par diffraction des rayons X et par des mesures magnétiques : la substitution de l’aluminium au cobalt entraîne une surlithiation moindre, un taux d’échange Li+ / Ni2+ plus important et par conséquent une diminution du caractère bidimensionnel de la structure. Ces matériaux présentent une bonne cyclabilité même à des régimes élevés et une stabilité thermique améliorée à l’état désintercalé. / Two approaches were considered for the optimization of Li1+x(Ni1/2-yMn1/2-yCo2y)1-xO2 positive electrode materials for lithium-ion batteries : the surface modification (coating) and partial substitution. First, we showed that fluorine substitution for oxygen is not effective, on the contrary to the hypotheses proposed in literature by others authors: in fact a thin LiF layer is formed at the surface of these materials irrespective of the synthesis route. These "coated" materials show a better cyclability. Their structural and physicochemical properties were characterized mainly by X-ray diffraction, 7Li and 19F MAS NMR spectroscopy and Auger electron spectroscopy. Secondly, we studied the effect of aluminum (electrochemically inert) substitution for cobalt within these layered materials rich in nickel and manganese. The synthesis conditions were optimized and an interesting material was thus proposed. The structure and cationic distribution were determined by chemical analyses, X-ray diffraction, magnetic measurements: aluminum substitution leads to a lower overlithiation, to a larger exchange Li+ / Ni2+ ratio and thus to a decreasing bidimensional character for the structure. These materials show a good cyclability even at high rates and an improved thermal stability in the deintercalated state.

No description available.

Ce travail vise à identifier l’impact potentiel des impulsions périodiques de courant sur laperformance et la durée de vie des accumulateurs graphite/LiFePO4. Il apparait que,contrairement aux résultats connus pour les accumulateurs Plomb-acide et à ceux annoncéspar certains auteurs de la littérature pour les accumulateurs Li-ion, l’application d’impulsionspériodiques de courant ne présente pas d’intérêt dans une logique d’amélioration de laperformance et/ou de la durée de vie des accumulateurs Li-ion. De surcroit, certains typesd’impulsions ont été identifiés pour entrainer des effets préjudiciables à ces derniers. En seréférant à une application de véhicule industriel hybride électrique, nous avons évalué sur descritères techniques et économiques l’intérêt d’implémenter un système de stockage d’énergiecombiné, c'est-à-dire mutualisant l’usage d’une batterie Li-ion et desupercondensateurs/condensateurs. Il apparait que les stratégies consistant à agir sur lescomposantes hautes fréquences du signal pour ajouter/retirer des impulsions du profil vu parla batterie ne permettent pas d’accéder à des allongements de durée de vie qui pourraientcompenser le surcoût actuel lié à l’implémentation de ces systèmes. En outre, il apparait quele meilleur levier d’optimisation du bilan technique et économique associé au système destockage d’énergie est son dimensionnement. En effet, même si les systèmes de stockaged’énergie combinés utilisant les supercondensateurs permettent d’atteindre des réductions duratio coût/durée de vie considérables, la prise en compte globale des critères de coût, de duréede vie, de masse et d’encombrement s’avère plus favorable à la solution constituée d’unebatterie seule, de taille optimisée vis-à-vis de son application. / This work aims to identify the possible impact of periodic current pulses on both performanceand lifetime of graphite/LiFePO4 secondary batteries. Contrary to the well-known results onlead-acid batteries and to results announced in previously published works, periodic pulses donot bring any benefit to the performance and the lifetime of Li-ion batteries. Moreover,certain pulse types have been identified to be detrimental to Li-ion batteries. Using the hybridelectric vehicle application as a reference, we evaluated both the technical and economicalaspects of implementing combined energy storage systems composed with Li-ion batteriesand supercapacitors/capacitors. We found that the control strategies acting on high frequencyharmonics of the current signal to adding/retrieving pulses to the Li-ion battery profile doesnot prolong its life enough to compensate the extra cost of such system implementation.Furthermore, it seems that the best way to optimize the technico-economic balance of theenergy storage system is the sizing. Even if combined energy storage systems using Li-ionbatteries and supercapacitors enable to considerably increase the lifetime/cost ratio, a generalconsideration of the criteria cost, life, mass and volume is more favorable to a solution whereone single Li-ion battery is optimally sized for its application.

De nouvelles architectures de traction (hybride, électrique) entrent en concurrence avec les motorisations thermiques conventionnelles. Des batteries Lithium-ion équipent ces véhicules innovants. La durabilité de ces batteries constitue un enjeu majeur mais dépend de nombreux paramètres environnementaux externes. Les outils de prédiction de durée de vie actuellement utilisés sont souvent trop simplificateurs dans leur approche. L’objet de ces travaux consiste à caractériser les conditions d’usage de ces batteries (température, tension, courant, SOC et DOD) afin d’étudier avec précision la durée de vie que l’on peut en attendre en fonction de l’application visée. Différents types de véhicules électrifiés (vélos à assistance électrique, voitures électriques, voitures hybrides, et trolleybus) ont été instrumentés afin de documenter les conditions d’usage réel des batteries. De larges volumes de données ont été recueillis puis analysés au moyen d’une méthode innovante qui s’appuie sur la classification d’impulsions de courant par l’algorithme des K-means et la génération de cycles synthétiques par modélisation par chaine de Markov. Les cycles synthétiques ainsi obtenus présentent des caractéristiques très proches de l’échantillon complet de données récoltées et permettent donc de représenter fidèlement l’usage réel. Utilisés lors de campagnes de vieillissement de batteries, ils sont susceptibles de permettre l’obtention d’une juste prédiction de la durée de vie des batteries pour l’application considérée. Plusieurs résultats expérimentaux sont présentés afin d’étayer la pertinence de cette approche / Lithium-ion batteries are being used as energy storage systems in recent electric and hybrid electric vehicles coming to market. Current cycle-life estimation techniques show evidence of discrepancy between laboratory results and real-world results. This work is aimed at characterizing actual battery usage in electrified transportation applications. Factors such as temperature, State Of Charge, Depth Of Discharge, current and voltage have to be carefully considered for accurate cycle-life prediction within a given application. Five electrified vehicles have been studied (two electric bicycles, one light EV, one mainstream HEV and one Heavy-Duty trolleybus). These vehicles have been equipped with sensors and data-logger and then test-driven on open roads under real-world conditions. Large amounts of data have been stored and later processed through an innovative method for analysis of actual usage. This method relies on data mining based on K-means clustering and synthetic duty cycle generation based on Markov chain modeling. Resulting synthetic cycles exhibit features similar to those observed on the large original datasets. This enables accurate prediction of cycle-life through realistic ageing trials of Lithium-ion batteries. Several experimental results are presented in order to assess the fitness of this method

The magnificent development of on-board solutions for electronics has resulted in the race towards scaling down of autonomous micro-power sources. In order to maintain the reliability of miniaturized devices and to reduce the power dissipation in high density memories like CMOS RAM, localized power for such systems is highly desirable. Therefore these micro-power sources need to be integrated in to the electronic chip level, which paved the way for the research and development of rechargeable thin film batteries (TFB). A Thin film battery is defined as a solid-state electrochemical source fabricated on the same scale as and using the same type of processing techniques used in microelectronics. Various aspects of deposition and characterization of LiCoO2/LiPON/Sn thin film battery are investigated in this thesis. Prior to the fabrication of thin film battery, individual thin film layers of cathode-LiCoO2, electrolyte-LiPON and anode-Sn were optimized separately for their best electrochemical performance. Studies performed on cathode layer include theoretical and experimental aspects of deposition of electrochemically active LiCoO2 thin films. Mathematical simulation and experimental validation of process kinetics involved in sputtering of a LiCoO2 compound target have been performed to analyze the effect of process kinetics on film stoichiometry. Studies on the conditioning of a new LiCoO2 sputtering target for various durations of pre-sputtering time were performed with the help of real time monitoring of glow discharge plasma by OES and also by analysing surface composition, and morphology of the deposited films. Films deposited from a conditioned target, under suitable deposition conditions were electrochemically tested for CV and charge/discharge, which showed an initial discharge capacity of 64 µAh/cm2/µm. Studies done on the deposition and characterization of solid electrolyte layer-LiPON have shown that, sputtering from powder target can be useful for certain compounds like Li3PO4 in which breaking of ceramic target and loss of material are severe problems. An ionic conductivity of 1.1 x10-6 S/cm was obtained for an Nt/Nd ratio of 1.42 for a RF power density of 3 W/cm2 and N2 flow of 30 sccm. Also the reasons for reduction in ionic conductivity of LiPON thin films on exposure to air have been analyzed by means of change in surface morphology and surface chemistry. Ionic conductivity of 2.8 x10-6 S/cm for the freshly deposited film has dropped down to 9.9 x10-10 S/cm due to the reaction with moisture, oxygen and carbon content of exposed air. Interest towards a Li-free thin film battery has prompted to choose Sn as the anode layer due to its relatively good electrochemical capacity compared with other metallic thin films and ease of processing. By controlling the rate of deposition of Sn, thin films of different surface morphology, roughness and crystallinity can be obtained with different electrochemical performance. The reasons for excessive volume changes during lithiation/delithiation of a porous Sn thin film have been analyzed with the aid of physicochemical characterization techniques. The results suggest that the films become progressively pulverized resulting in increased roughness with an increase in lithiation. Electrochemical impedance data suggest that the kinetics of charging becomes sluggish with an increase in the quantity of Li in Sn-Li alloy. Thin film batteries with configuraion LiCoO2/LiPON/Sn were fabricated by sequential sputter deposition on to Pt/Si substartes. Pt/Cu strips were used as the current collector leads with a polymer packaging. Electrochemical charge/discharge studies revealed discharge capacities in the range 6-15 µAh/cm2/µm with hundreds of repeated cycles. TFB with a higher capacity of 35 µAh/cm2/µm suffered capacity fade out after 7 cycles, for which reasons were analyzed. The surface and cross-sectional micrographs of cycled TFB showed formation of bubble like features on anode layer reducing integrity of electrolyte-anode interface. The irreversible Li insertion along with apparent surface morphology changes are most likely the main reasons for the capacity fade of the LiCoO2/LiPON/Sn TFB.

Transition metals (TMs) are ‘elements whose atoms have partially filled d-shell, or which can give rise to cations with an incomplete d-shell’. In TMs, the d-shell overlaps with next higher s-shell. Most of the TMs exhibit more than one (multiple) oxidation states. Some TMs, such as silver and gold, occur naturally in their metallic state but, most of the TM minerals are generally oxides. Most of the minerals on the planet earth are metal oxides, because of large free energies of formation for the oxides. The thermodynamic stability of the oxides is determined from the Ellingham diagram. Ellingham diagram shows the temperature dependence of the stability (free energy) for binaries such as metal oxides. Ellingham diagram also shows the ease of reducibility of metal oxides. TM oxides of general formulas MO, M2O3, MO2, M2O5, MO3 are known to exist, many of them being the ultimate products of oxidation in air in their highest oxidation states. In addition, TM oxides also exist in lower oxidation states which are prepared under controlled conditions. The nature of bonding in these oxides varies from mainly ionic (e.g. NiO, CoO) to mainly covalent (e.g. OsO4). Simple binary oxides of the compositions, MO, generally possess the rock salt structure (e.g. NiO), while the dioxides, MO2, possess the rutile structure (e.g. TiO2); many sesquioxides, M2O3, possess the corundum structure (e.g. Cr2O3). TMs form important ternary oxides like perovskites (e.g. CaTiO3), spinels (e.g. MgFe2O4) and so on. In TM oxides, the valence (outer) d-shell could be empty, d0 (e. g. TiO2), partially filled, dn (1≤ n≤ 9) (e.g. TiO, VO, NiO etc.) or completely filled, d10 (e.g. ZnO, CdO, Cu2O etc.). The outer d electrons in TM oxides could be localized or delocalized. Localized outer d electrons give insulators/semiconductors, while delocalized/itinerant d electrons make the TM oxide ‘metallic’ (e.g. ReO3, RuO2). Partially filled dn states are normally expected to give rise to itinerant (metallic) electron behaviour. But most of TM oxides with partially filled d shell are insulators because of special electronic energy (correlation energy) involved in d electron transfer to adjacent sites. Such insulating TM oxides are known as Mott insulators (e. g. NiO, CoO etc.). Certain TM oxides are known to exhibit both localized (insulating) and itinerant (metallic) behaviour as a function of temperature or pressure. For example, VO2 shows a insulator–metal transition at ~340K. Similar transitions are also known for V2O3, metal-rich EuO and so on. The chemical composition and bonding of TM oxides, which determine the crystal and electronic structures, give rise to functional properties. Table 1 gives representative examples. Properties like ionic conductivity and diffusion are governed by both the crystal structure and the defect structure (point defects), whereas properties such as magnetism and electron transport mainly arise from the electronic structures of the materials. Accordingly, TM oxides provide a platform for exploring functional materials properties. Among the various functional materials properties exhibited by transition metal oxides, the present thesis is devoted to investigations of lithium ion battery cathodes, inorganic pigments and magnetic perovskites. Over the years, most of the lithium containing first row transition metal oxides of rock salt derived structure have been investigated for possible application as cathode materials in lithium ion batteries (LIBs). First major breakthrough in LIBs research was achieved by electrochemically deinserting and inserting lithium in LiCoO2. A new series of cathode materials for LIBs were prepared by incorporating excess lithium into the transition metal containing layered lithium oxides through solid solution formation between Li2MnO3–LiMO2 (M = Cr, Mn, Fe, Co, Ni), known as lithium-rich layered oxides (LLOs). LLOs exhibit improved electrochemical performance as compared to the corresponding end members and hence received significant attention as a potential next generation cathode materials for LIBs in recent times. LiCoO2 (R-3m) crystallizes in the layered α-NaFeO2 structure with the oxygens in a ccp arrangement. Li+ and Co3+ ions almost perfectly order in the octahedral sites (3a and 3b) to give alternating (111) planes of LiO6 and CoO6 octahedra. Table 1. Materials properties exhibited by representative TM oxides. Property Example(s) Ferroelectricity BaTiO3, PbTiO3, Bi4Ti3O12 Nonlinear Optical Response LiNbO3 Multiferroic response BiFeO3, TbMnO3 Microwave dielectric properties Ba3ZnTa2O9 Relaxor Dielectric Properties Pb3MgNb2O9, Colossal Magnetoresistance Tl2Mn2O7 Metallic ‘Ferroelectricity’ Cd2Re2O7 Superconductivity AOs2O6(A = K, Rb, Cs) Redox deinsertion/insertion of LiCoO2 lithium Photocatalysis/water splitting TiO2 Pigment Ca(1-x)LaxTaO(2-x)N1+x (yellow-red), YIn1-xMnxO3 (blue) Metallic Ferromagnetism CrO2 Antiferromagnetism NiO, LaFeO3 Zero thermal expansion ZrW2O8 The reversible capacity of LiCoO2 in common LIBs is relatively low at around 140 mA h g-1 (half of theoretical capacity), corresponding to: LiCo3+O2 → Li0.5Co3+0.5Co4+0.5O2 + 0.5Li+ + 0.5e– . Substitution of one or more transition metal ions in LiCOO2 has been explored to improve the electrochemical performance. The structure of LLOs is described as a solid solution or nano composite of Li2MnO3 (C2/m) and LiMO2 (R-3m). The electrochemical deinsertion/insertion behaviour of LLOs is complex and also not yet understood completely. The present thesis consists of four parts. After a brief introduction (Part 1), Part 2 is devoted to materials for Li-ion battery cathode, consisting of three Chapters 2.1, 2.2 and 2.3. In Chapter 2.1, we describe the synthesis, crystal structure, magnetic and electrochemical characterization of new LiCoO2 type rock salt oxides of formula, Li3M2RuO6 (M = Co, Ni). The M =Co oxide adopts the LiCoO2 (R-3m) structure, whereas the M = Ni oxide also adopts a similar layered structure related to Li2TiO3. Magnetic susceptibility measurements reveal that in Li3Co2RuO6, the oxidation states of transition metal ions are Co3+, Co2+ and Ru4+, whereas in Li3Ni2RuO6, the oxidation states are Ni2+ and Ru5+. Li3Co2RuO6 orders antiferromagnetically at ~10K. On the other hand, Li3Ni2RuO6 presents a ferrimagnetic behaviour with a Curie temperature of ~100K. Electrochemical Li-deinsertion/insertion studies show that high first charge capacities (between ca.160 and 180 mA h g−1) corresponding to ca.2/3 of theoretical capacity are reached albeit, in both cases, capacity retention and cyclability are not satisfactory. Chapter 2.2 presents a study of new ruthenium containing LLOs, Li3MRuO5 (M = Co and Ni). Both the oxides crystallize in the layered LLO type LiCoO2 (α-NaFeO2) structure consisting of Li[Li0.2M0.4Ru0.4]O2 layers. Magnetic susceptibility data suggest that the oxidation states of transition metals are Li3Co3+Ru4+O5 for the M = Co compound and Li3Ni2+Ru5+O5 for the M = Ni compound. Electrochemical investigations of lithium deintercalation–intercalation behaviour reveal that both Co and Ni phases exhibit attractive specific capacities of ca. 200 mA h g-1 at an average voltage of 4 V, that has been interpreted as due to the oxidation of Co3+ and Ru4+ in Li3CoRuO5 and Ni2+ to Ni4+ in the case of Li3NiRuO5. Thus, we find that ruthenium plays a favourable role in LLOs than in non-LLOs in stabilizing higher reversible electrochemical capacities. In Chapter 2.3, we describe the synthesis, crystal structure and lithium deinsertion–insertion electrochemistry of two new LLOs, Li3MRuO5 (M=Mn, Fe) which are analogs of the oxides described in Chapter 2.2. The Li3MnRuO5 oxide adopts a structure related to Li2MnO3 (C2/m), while the Li3FeRuO5 oxide adopts a near-perfect LiCoO2 (R-3m) structure. Lithium electrochemistry shows typical behaviour of LLOs for both oxides, where participation of oxide ions in the electrochemical processes is observed. A long first charge process with capacities of 240 mA h g-1 (2.3 Li per f.u.) and 144 mA h g-1 (1.38 Li per f.u.) is observed for Li3MnRuO5 and Li3FeRuO5, respectively. Further discharge–charge cycling points to partial reversibility. X-ray photoelectron spectroscopy (XPS) characterisation of both pristine and electrochemically oxidized Li3MRuO5 reveals that in the Li3MnRuO5 oxide, Mn3+ and Ru4+ are partially oxidized to Mn4+ and Ru5+ in the sloping region at low voltage, while in the long plateau, O2- is also oxidized. In the Li3FeRuO5 oxide, the oxidation process appears to affect only Ru (4+ to 5+ in the sloping region) and O2- (plateau), while Fe seems to retain its 3+ state. Another characteristic feature of TMs is formation of several coloured solid materials where d–d transitions, band gap transitions and charge transfer transitions are involved in the colouration mechanism. Coloured TM oxides absorbing visible light find important applications as visible light photocatalyst (for example, yellow BiVO4 for solar water splitting and red Sr1-xNbO3 for oxidation of methylene blue) and inorganic pigments [for example, Egyptian blue (CaCuSi4O10), Malachite green (Cu2CO3(OH)2), Ochre red (Fe2O3)]. Pigments are applied as colouring materials in inks, dyes, paints, plastics, ceramic glazers, enamels and textiles. In this thesis, we have focused on the coloured TM oxides for possible application as inorganic pigments. Generally, colours arise from electronic transitions that absorb visible light. Colours of the inorganic pigments arise mainly from electronic transitions involving TM ions in various ligand fields and charge transfer transitions governed by different selection rules. The ligand field d–d transitions are parity forbidden but are relaxed due to various reasons, such as distortion (absence of center of inversion) and vibronic coupling. The d-electrons can be excited by light absorption in the visible region of the spectrum imparting colour to the material. Charge transfer transitions in the visible region are not restricted by the parity selection rules and therefore give intense colours. Here we have investigated the colours of manganese in unusual oxidation state (Mn5+) as well as the colours of different 3d-TM ions in distorted octahedral and trigonal prismatic sites in appropriate colourless crystalline host oxides. These results are discussed in Part 3 of the thesis. In Chapter 3.1, we describe a blue/green inorganic material, Ba3(P1−xMnxO4)2 (I) based on tetrahedral Mn5+O4 :3d2 chromophore. The solid solutions (I) which are sky-blue and turquoise-blue for x ≤ 0•25 and dark green for x ≥ 0•50, are readily synthesized in air from commonly available starting materials, stabilizing the Mn5+O4 chromophore in an isostructural phosphate host. We suggest that the covalency/ionicity of P–O/Mn–O bonds in the solid solutions tunes the crystal field strength around Mn(V) such that a blue colour results for materials with small values of x. The material could serve as a nontoxic blue/green inorganic pigment. In Chapter 3.2, an experimental investigation of the stabilization of the turquoise-coloured Mn5+O4 chromophore in various oxide hosts, viz., A3(VO4)2 (A = Ba, Sr, Ca), YVO4, and Ba2MO4 (M = Ti, Si), has been carried out. The results reveal that substitution of Mn5+O4 occurs in Ba3(VO4)2 forming the entire solid solution series Ba3(V1−xMnxO4)2 (0 < x ≤ 1.0), while, with the corresponding strontium derivative, only up to about 10% of Mn5+O4 substitution is possible. Ca3(VO4)2 and YVO4 do not stabilize Mn5+O4 at all. With Ba2MO4 (M = Ti, Si), we could prepare only partially substituted materials, Ba2M1−xMn5+xO4+x/2 for x up to 0.15, that are turquoise-coloured. We rationalize the results that a large stabilization of the O 2p-valence band states occurs in the presence of the electropositive barium that renders the Mn5+ oxidation state accessible in oxoanion compounds containing PO43−, VO43−, etc. By way of proof-of-concept, we synthesized new turquoise-coloured Mn5+O4 materials, Ba5(BO3)(MnO4)2Cl and Ba5(BO3)(PO4)(MnO4)Cl, based on the apatite – Ba5(PO4)3Cl – structure. Chapter 3.3 discusses crystal structures, and optical absorption spectra/colours of 3d-transition metal substituted lyonsite type oxides, Li3Al1-xMIIIx(MoO4)3 (0< x ≤1.0) (MIII = Cr, Fe) and Li3-xAl1-xMII2x(MoO4)3 (0< x ≤1.0) (MII = Co, Ni, Cu). Crystal structures determined from Rietveld refinement of PXRD data reveal that in the smaller trivalent metal substituted lyonsite oxides, MIII ions occupy the octahedral (8d, 4c) sites and the lithium ions exclusively occur at the trigonal prismatic (4c) site in the orthorhombic (Pnma) structure; on the other hand, larger divalent cations (CoII/CuII) substituted derivatives show occupancy of CoII/CuII ions at both the octahedral and trigonal prismatic sites. We have investigated the colours and optical absorption spectra of Li3Al1-xMIIIx(MoO4)3 (MIII = Cr, Fe) and Li3-xAl1-xMII2x(MoO4)3 (MII = Co, Ni, Cu) and interpreted the results in terms of average crystal field strengths experienced by MIII/MII ions at multiple coordination geometries. We have also identified the role of metal-to-metal charge transfer (MMCT) from the partially filled transition metal 3d orbitals to the empty Mo – 4d orbitals in the resulting colours of these oxides. B The ABO3 perovskite structure consists of a three dimensional framework of corner shared BO6 octahedra in which large A cation occupies dodecahedral site, surrounded by twelve oxide ions. The ideal cubic structure occurs when the Goldschmidt’s tolerance factor, t = (rA + rO)/{√2(rB + rO)}, adopts a value of unity and the A–O and B–O bond distances are perfectly matched. The BO6 octahedra tilt and bend the B – O – B bridges co-operatively to adjust for the non-ideal size of A cations, resulting deviation from ideal cubic structure to lower symmetries. Ordering of cations at the A and B sites of perovskite structure is an important phenomenon. Ordering of site cations in double (A2BB'O6) and multiple (A3BB'2O9) perovskites give rise to newer and interesting materials properties. Depending upon the constituent transition metals and ordering, double perovskite oxides exhibit a variety of magnetic behaviour such as ferromagnetism, ferrimagnetism, antiferromagnetism, spin-glass magnetism and so on. We also have coupled magnetic properties such as magnetoresistance (Sr2FeMoO6), magnetodielectric (La2NiMnO6) and magnetooptic (Sr2CrWO6) behaviour. Here we have investigated new magnetically frustrated double perovskite oxides of the formula Ln3B2RuO9(B = Co, Ni and Ln = La, Nd). The Chapter 4.1 describes Ln3B2RuO9 (B = Co, Ni and Ln = La, Nd) oxides (prepared by a solid state metathesis route) which adopt a monoclinic (P21/n) A2BB'O6 double perovskite structure, wherein the two independent octahedral 2c and 2d sites are occupied by B2+ and (B2+1/3Ru5+2/3) atoms, respectively. Temperature dependence of the molar magnetic susceptibility plots obtained under zero field cooled (ZFC) condition exhibit maxima in the temperature range 25–35K, suggesting an antiferromagnetic interaction in all these oxides. Ln3B2RuO9 oxides show spin-glass behavior and no long-range magnetic order is found down to 2 K. The results reveal the importance of competing nearest neighbour (NN), next nearest neighbor (NNN) and third nearest neighbour (third NN) interactions between the magnetic Ni2+/Co2+ and Ru5+ atoms in the partially ordered double perovskite structure that conspire to thwart the expected ferromagnetic order in these materials.