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1
Clark, John. "Computer modelling of positive electrode materials for lithium and sodium batteries." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616648.
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Providing cleaner sources of energy will require significant improvements to the solid-state materials available for energy storage and conversion technologies. Rechargeable lithium and sodium batteries are generally regarded as the best available candidates for future energy storage applications, particularly with regard to implementation within hybrid or fully electric vehicles, due to their high energy density. However, production of the next generation of rechargeable batteries will require significant improvements in the materials available for the cathode, anode and electrolyte. Modern computer modelling techniques enable valuable insights into the fundamental defect, ion transport and voltage properties of battery materials at the atomic level. Polyanionic framework materials are being investigated as alternative cathodes to LiCoO2 in Li-ion batteries largely due to their greater stability, cost and environmental benefits. In this thesis, four types of polyanion materials are examined using computational techniques. Firstly, the pyrophosphate material, Li2FeP2O7 is investigated, which has the highest voltage (3.5 V) for an iron-based phosphate cathode. In this pyrophosphate material the anti-site defect in which the Li+ and Fe2+ cations exchange positions is the intrinsic defect type found with the lowest energy. Lithium ion diffusion will follow non-linear, curved paths in the b-axis and c-axis directions, which show low migration energies. Hence, in contrast to 1D diffusion in LiFePO4, fast Li+ transport in Li2FeP2O7 is predicted to be through a 2D network in the bc-plane, which is important for good rate capability and for the function of particles without nano-sizing. Favourable doping is found for Na+ on the Li+ site, and isovalent dopants (e.g., Mn2+, Co2+, Cu2+) on the Fe2+ site; the latter could be used in attempts to increase the Fe2+/Fe3+ redox potential towards 4V. Secondly, the relative abundance and low cost associated with Na-ion batteries now make them an attractive alternative for large-scale grid storage. Therefore, defect chemistry and ion migration results are presented for the sodium-based pyrophosphate framework, Na2MP2O7 (where M = Fe, Mn). Formation energies for Na/M ion exchange are found to be higher than Li/Fe exchange, which has been related to the larger size of the Na ion compared to the Li ion. Low activation energies are found for long-range diffusion in all crystallographic directions in Na2MP2O7 suggesting three-dimensional (3D) Na-diffusion. Thirdly, the search for high voltage cathodes for lithium-ion batteries has led to recent interest in the Li2Fe(SO4)2 material which has a voltage of 3.83 V vs lithium, the highest recorded for a fluorine-free iron-based compound. Ion conduction paths through the Li2M(SO4)2 (M = Fe, Mn, Co) marinite family of cathode materials, show low activation energies for lithium migration along the a-axis channels giving rise to long-range 1D diffusion, supported by molecular dynamics (MD) simulations. Density functional theory (DFT) simulations were used to reproduce the observed high voltage of Li2Fe(SO4)2 and to make predictions of the voltages of both Li2Mn(SO4)2 and Li2Co(SO4)2, and also examine local structural distortions on lithium extraction. Finally, the layered and tavorite polymorphs of LiFeSO4OH have recently attracted interest as sustainable cathode materials offering low temperature synthesis routes. Using DFT techniques the experimental voltage and structural parameters are accurately reproduced for the tavorite polymorph. An important result for the layered structure, is that similar accuracy in both cell voltage and structure can only be obtained if a van der Waals functional is included in the DFT methodology to account for the inter-layer binding.
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Blidberg, Andreas. "Iron Based Materials for Positive Electrodes in Li-ion Batteries : Electrode Dynamics, Electronic Changes, Structural Transformations." Doctoral thesis, Uppsala universitet, Strukturkemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-317014.
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Li-ion battery technology is currently the most efficient form of electrochemical energy storage. The commercialization of Li-ion batteries in the early 1990’s revolutionized the portable electronics market, but further improvements are necessary for applications in electric vehicles and load levelling of the electric grid. In this thesis, three new iron based electrode materials for positive electrodes in Li-ion batteries were investigated. Utilizing the redox activity of iron is beneficial over other transition metals due to its abundance in the Earth’s crust. The condensed phosphate Li2FeP2O7 together with two different LiFeSO4F crystal structures that were studied herein each have their own advantageous, challenges, and scientific questions, and the combined insights gained from the different materials expand the current understanding of Li-ion battery electrodes. The surface reaction kinetics of all three compounds was evaluated by coating them with a conductive polymer layer consisting of poly(3,4-ethylenedioxythiophene), PEDOT. Both LiFeSO4F polymorphs showed reduced polarization and increased charge storage capacity upon PEDOT coating, showing the importance of controlling the surface kinetics for this class of compounds. In contrast, the electrochemical performance of PEDOT coated Li2FeP2O7 was at best unchanged. The differences highlight that different rate limiting steps prevail for different Li-ion insertion materials. In addition to the electrochemical properties of the new iron based energy storage materials, also their underlying material properties were investigated. For tavorite LiFeSO4F, different reaction pathways were identified by in operando XRD evaluation during charge and discharge. Furthermore, ligand involvement in the redox process was evaluated, and although most of the charge compensation was centered on the iron sites, the sulfate group also played a role in the oxidation of tavorite LiFeSO4F. In triplite LiFeSO4F and Li2FeP2O7, a redistribution of lithium and iron atoms was observed in the crystal structure during electrochemical cycling. For Li2FeP2O7, and increased randomization of metal ions occurred, which is similar to what has been reported for other iron phosphates and silicates. In contrast, triplite LiFeSO4F showed an increased ordering of lithium and iron atoms. An electrochemically induced ordering has previously not been reported upon electrochemical cycling for iron based Li-ion insertion materials, and was beneficial for the charge storage capacity of the material.
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Sun, Meiling. "Elaboration of novel sulfate based positive electrode materials for Li-ion batteries." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066686/document.
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Le besoin croissant de batteries à ions lithium dans notre société exige le développement de matériaux d'électrode positive, avec des exigences spécifiques en termes de densité énergétique, de coût et de durabilité. Dans ce but, nous avons exploré quatre composés à base de sulfate: un fluorosulfate - LiCuSO4F et une famille d'oxysulfates - Fe2O(SO4)2, Li2Cu2O(SO4)2 and Li2VO(SO4)2. Leur synthèse, structure et performances électrochimiques sont présentées pour la première fois. Étant électrochimiquement inactif, LiCuSO4F présente une structure triplite ordonnée qui est distincte des autres fluorosulfates. L'activité électrochimique des composés oxysulfate a été explorée face au lithium. Plus spécifiquement, Fe2O(SO4)2 délivre une capacité réversible d'environ 125 mA∙h/g à 3.0 V par rapport à Li+/Li0; Li2VO(SO4)2 et Li2Cu2O(SO4)2 présentent respectivement les potentiels les plus élevés de 4.7 V vs. Li+/Li0 parmi les composés à base de V et de Cu. Enfin, la phase Li2Cu2O(SO4)2 révèle la possibilité d'une activité électrochimique anionique dans une électrode positive polyanionique. Leurs propriétés physiques, telles que les conductivités ioniques et les propriétés magnétiques, sont également rapportées. Dans l'ensemble, les oxysulfates sont intéressants à étudier en tant qu'électrodes positives polyanioniques pour les batteries à ions lithiumThe increasing demand of our society for Li-ion batteries calls for the development of positive electrode materials, with specific requirements in terms of energy density, cost, and sustainability. In such a context, we explored four sulfate based compounds: a fluorosulfate – LiCuSO4F, and a family of oxysulfates – Fe2O(SO4)2, Li2Cu2O(SO4)2 and Li2VO(SO4)2. Herein their synthesis, structure, and electrochemical performances are presented for the first time. Being electrochemically inactive, LiCuSO4F displays an ordered triplite structure which is distinct from other fluorosulfates. The electrochemical activity of the oxysulfate compounds was explored towards lithium. Specifically, Fe2O(SO4)2 delivers a sustained reversible capacity of about 125 mA∙h/g at 3.0 V vs. Li+/Li0; Li2VO(SO4)2 and Li2Cu2O(SO4)2 respectively exhibit the highest potential of 4.7 V vs. Li+/Li0 among V- and Cu- based compounds. Last but not least, the Li2Cu2O(SO4)2 phase reveals the possibility of anionic electrochemical activity in a polyanionic positive electrode. Their physical properties, such as ionic conductivities and magnetic properties are also reported. Overall, this makes oxysulfates interesting to study as polyanionic positive electrodes for Li-ion batteries
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Martin, Andréa Joris Quentin. "Nano-sized Transition Metal Fluorides as Positive Electrode Materials for Alkali-Ion Batteries." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21619.
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Übergangsmetallfluoridverbindungen sind sehr vielversprechende Kandidaten für die nächste Generation von Kathoden für Alkaliionenbatterien. Dennoch verhindern einige Nachteile dieser Materialklasse ihre Anwendung in Energiespeichermedien. Metallfluoride haben eine stark isolierende Wirkung, außerdem bewirken die Mechanismen beim Lade-/Entladevorgang, große Volumenänderungen und somit eine drastische Reorganisation des Materials, welche nur geringfügig umkehrbar ist. Um diese Nachteile zu reduzieren, werden in dieser Arbeit innovative Syntheserouten für die Umwandlung von Metallfluoridverbindungen sowie deren Anwendung in Alkaliionenbatterien vorgestellt. Im ersten Teil werden MFx Verbindungen (M = Co, Fe; x = 2 oder 3) untersucht. Diese Materialien zeigen eine hohe Ausgangskapazität aber nur bei sehr geringen C-Raten und zudem sehr geringe Zyklisierbarkeiten. Ex-situ-XRD und -TEM zeigen, dass die geringe Umkehrbarkeit der Prozesse hauptsächlich aus der Umwandlungsreaktion während des Be-/Entladens resultieren. Im zweiten Teil werden sowohl die Synthesen als auch die elektrochemischen Eigenschaften von Perowskiten aus Übergangsmetallfluoriden vorgestellt. NaFeF3 zeigt hierbei exzellente Leistungen und Reversibilitäten. Die Untersuchung der Mechansimen durch ex-situ und operando XRD während der Be- und Entladeprozesse hinsichtlich verschiedener Alkalisysteme zeigt, dass das kristalline Netzwerk über den Zyklus erhalten bleibt. Dies führt zur hohen Reversibilität und hohen Leistung selbst bei hohen C-Raten. Der Erhalt der Kristallstruktur wird durch elektrochemische Stabilisierung der kubischen Konformation von FeF3 ermöglicht, welche normalerweise erst bei hohen Temperaturen (400 °C) beobachtet wird und durch geringere Reorganisationen innerhalb des Kristallgerüsts erklärt werden kann. Ähnliche elektrochemische Eigenschaften können für KFeF3 und NH4FeF3 beobachtet werden, wobei erstmalig von Ammoniumionen als Ladungsträger in Alkaliionensystemen berichtet wird.Metal fluoride compounds appear as very appealing candidates for the next generation of alkali-ion battery cathodes. However, many drawbacks prevent this family of compounds to be applicable to storage systems. Metal fluorides demonstrate a high insulating character, and the mechanisms involved during the discharge/charge processes atom engender large volume changes and a drastic reorganization of the material, which induces poor reversibility. In order to answer these problematics, the present thesis reports the elaboration of innovative synthesis routes for transition metal fluoride compounds and the application of these fluoride materials in alkali-ion battery systems. In a first part, MFx compounds (M = Co, Fe; x = 2 or 3) are studied. Those compounds exhibit high initial capacity but very poor cyclability and low C-rate capabilities. Ex-situ X-ray diffraction and transmission electron microscopy demonstrate that the low reversibility of the processes is mainly due to the conversion reaction occurring during their discharge/charge. In the second part, the syntheses of transition metal fluoride perovskites are reported, as well as their electrochemical properties. NaFeF3 demonstrates excellent performances and reversibility. The study of the mechanisms occurring during its charge/discharge processes towards different alkali systems by ex-situ and operando X-ray diffraction reveals that its crystalline framework is maintained along the cycles, resulting in high reversibility and excellent C-rate performance. This retention of the crystal framework is possible by an electrochemical stabilization of a cubic conformation of FeF3, which is usually only observable at high temperature (400 °C), and can be explained by lower reorganizations within the crystal framework. Similar electrochemical properties could be observed for KFeF3 and NH4FeF3, where ammonium ions are reported for the first time as a charge carrier in alkali-ion systems.
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Chen, Chih-Yao. "A study on positive electrode materials for sodium secondary batteries utilizing ionic liquids as electrolytes." Kyoto University, 2014. http://hdl.handle.net/2433/192207.
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Boivin, Édouard. "Crystal chemistry of vanadium phosphates as positive electrode materials for Li-ion and Na-ion batteries." Thesis, Amiens, 2017. http://www.theses.fr/2017AMIE0032/document.
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Ce travail de thèse a pour but d'explorer de nouveaux matériaux de type structural Tavorite et de revisiter certains déjà bien connus. Dans un premier temps, les synthèses de compositions ciblées ont été réalisées selon des procédures variées (voies tout solide, hydrothermale, céramique assistée par sol-gel, broyage mécanique) afin de stabiliser d'éventuelles phases métastables et d'ajuster la microstructure impactant fortement les performances électrochimiques de tels matériaux polyanioniques. Ces matériaux ont ensuite été décrits en profondeur, dans leurs états originaux, depuis leurs structures moyennes, grâce aux techniques de diffraction (diffraction des rayons X sur poudres ou sur monocristaux et diffraction des neutrons) jusqu'aux environnements locaux, en utilisant des techniques de spectroscopie (résonance magnétique nucléaire à l'état solide, absorption des rayons X, infra-rouge et Raman). Par la suite, les diagrammes de phases et les processus d'oxydoréduction impliqués pendant l'activité électrochimique des matériaux ont été étudiés grâce à des techniques operando (diffraction et absorption des rayons X). La compréhension des mécanismes impliqués pendant le cyclage permet de mettre en évidence les raisons de leurs limitations électrochimiques : La synthèse de nouveaux matériaux (composition, structure, microstructure) peut maintenant être développée afin de contrepasser ces limitations et de tendre vers de meilleures performancesThis PhD work aims at exploring new Tavorite-type materials and at revisiting some of the well-known ones. The syntheses of targeted compositions were firstly performed using various ways (all solid state, hydrothermal, sol-gel assisted ceramic, ball milling) in order to stabilize eventual metastable phases and tune the microstructure impacting strongly the electrochemical performances of such polyanionic compounds. The materials were then described in-depth, at the pristine state, from their average long range structures, thanks to diffraction techniques (powder X-rays, single crystal X-rays and neutrons diffraction), to their local environments, using spectroscopy techniques (solid state Nuclear Magnetic Resonance, X-rays Absorption Spectroscopy, Infra-Red and/or Raman). Thereafter, the phase diagrams and the redox processes involved during electrochemical operation of the materials were investigated thanks to operando techniques (SXRPD and XAS). The in-depth understanding of the mechanisms involved during cycling allows to highlight the reasons of their electrochemical limitations: the synthesis of new materials (composition, structure and microstructure) can now be developed to overcome these limitations and tend toward better performance
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Martin, Andréa Joris Quentin [Verfasser]. "Nano-sized Transition Metal Fluorides as Positive Electrode Materials for Alkali-Ion Batteries / Andréa Joris Quentin Martin." Berlin : Humboldt-Universität zu Berlin, 2020. http://d-nb.info/1220690406/34.
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Gao, Shuang. "INVESTIGATION OF TRANSITION-METAL IONS IN THE NICKEL-RICH LAYERED POSITIVE ELECTRODE MATERIALS FOR LITHIUM-ION BATTERIES." UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/100.
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Layered lithium transition-metal oxides (LMOs) are used as the positive electrode material in rechargeable lithium-ion batteries. Because transition metals undergo redox reactions when lithium ions intercalate in and disintercalate from the lattice, the selection and composition of transition metals largely influence the electrochemical performance of LMOs. Recently, a Ni-rich compound, LiNi0.8Co0.1Mn0.1O2 (NCM811), has drawn much attention. It is expected to replace its state-of-the-art cousins, LiCoO2 (LCO) and LiNi1/3Co1/3Mn1/3O2 (NCM111), because of its higher capacity, lower cost, and reduced toxicity. However, the excess Ni, as a transition-metal element in NCM811, can cause structural and cycling instability.
Starting from NCM811, I modified the composition of transition metals by two approaches: 1) introducing cobalt deficiency and 2) substituting Ni, Co, and Mn with Zr. Their influences on the phase, structure, cycling performance, rate capability, and ionic transport were investigated by a variety of characterization techniques. I found that cobalt non-stoichiometry can suppress Ni2+/Li+ cation mixing, but simultaneously promotes the formation of oxygen vacancies, leading to rapid capacity fade and inferior rate capability compared to pristine NCM811. On the other hand, Zr can reside on and expand the lattice of NCM811, and form Li-rich lithium zirconates on their surfaces. In particular, 1% Zr substitution can increase the stability of NCM811 and facilitate Li-ion transport, resulting in enhanced cycling durability and high-rate performance. My studies help improve the understanding of the effects of transition metals on the degradation of the Ni-rich layered positive electrode material and provide modification strategies to enhance its performance and durability for Li-ion battery applications.
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Nakanishi, Shinji. "Studies on Reaction Mechanism of Lithium Air Secondary Battery and Effects of Carbonaceous Materials to Positive Electrode." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174954.
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Madsen, Alex. "Lithium iron sulphide as a positive electrode material for rechargeable lithium batteries." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355748/.
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Lithium iron sulphide has been investigated as a low-cost, high energy density and relatively safe positive electrode material for secondary lithium batteries. Lithium iron sulphide was synthesised, characterised and compared with natural pyrite samples and was shown to have a capacity of 350 mAh.g-1 upon cycling between 1.45 and 2.80 V vs. Li. The capacity was attributed to the Fe2+/Fe3+ redox couple at potentials up to 2.55 V, and oxidation of sulphur sites from Fe3+(S2-)2 to Fe3+S2-(S2)2-0.5 up to 2.80 V. The cycle life performance of lithium iron sulphide is poor when the cell is cycled between 1.45 and 2.80 V, with the cell loosing approximately 1.4 mAh.g-1 per cycle, although this performance is superior to comparable pyrite electrodes. Calcium doped samples of lithium iron sulphide were synthesised. Calcium doping was shown to impact upon lithium transport properties of the bulk lithium iron sulphide, improving the rate performance of the material. Improvements in cycle life performance of the calcium doped samples were offset by decreased specific capacity due to lithium substitution. The poor cycle life performance of lithium iron sulphide cells was attributed to the utilisation of the high voltage plateau corresponding to sulphur site oxidation/reduction. Experiments utilising a variety of negative electrode materials has identified the formation of soluble polysulphide species upon cycling of the cell, which reduce irreversibly at the negative electrode, contributing to active mass loss and poor cycle life performance. In-situ XRD studies have highlighted the structural decomposition that occurs upon utilisation of the sulphide, which results in irreversible amorphisation of the lithium iron sulphide crystal structure. Lithium iron sulphide was treated via coating with lithium boron oxide glass and a novel carbon coating method via thermal decomposition of butyl-methyl-pyrrolydinium-dicyanimide. Both treatments were shown to increase the cycle life performance of lithium iron sulphide, due to decreased dissolution of polysulphide upon cycling. The choice of binder, electrode formulation and electrolyte was also shown to impact upon the cycle life performance of lithium iron sulphide cells.
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Jokar, Ali. "An inverse method for estimating the electrochemical and the thermophysical parameters of lithium-ion batteries with different positive electrode materials." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11799.
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La sécurité de plusieurs systèmes électriques est fortement dépendante de la fiabilité de leur
bloc-batterie à base de piles aux ions lithium (Li-ion). Par conséquent, ces batteries doivent
être suivis et contrôlés par un système de gestion des batteries (BMS). Le BMS interagit
avec toutes les composantes du bloc-batterie de façon à maintenir leur intégrité. La
principale composante d’un BMS est un modèle représentant le comportement des piles Liion et capable de prédire ses différents points d’opération. Dans les industries de
l’électronique et de l’automobile, le BMS repose habituellement sur des modèles empiriques
simples. Ceux-ci ne sont cependant pas capables de prédire les paramètres de la batterie
lorsqu’elle vieillit. De plus, ils ne sont applicables que pour des piles spécifiques. D’un autre
côté, les modèles électrochimiques sont plus sophistiqués et plus précis puisqu’ils sont basés
sur la résolution des équations de transport et de cinétique électrochimique. Ils peuvent être
utilisés pour simuler les caractéristiques et les réactions à l’intérieur des piles aux ions
lithium.
Pour résoudre les équations des modèles électrochimiques, il faut connaître les différents
paramètres électrochimiques et thermo-physiques de la pile. Les variables les plus
significatives des piles Li-ion peuvent être divisées en 3 catégories : les paramètres
géométriques, ceux définissant les matériaux et les paramètres d’opération. Les paramètres
géométriques et de matériaux peuvent être facilement obtenus à partir de mesures directes
ou à partir des spécifications du manufacturier. Par contre, les paramètres d’opération ne
sont pas faciles à identifier. De plus, certains d’entre eux peuvent dépendre de la technique
de mesure utilisée et de l’âge. Finalement, la mesure de certains paramètres requiert le
démantèlement de la pile, une procédure risquée et destructive.
Plusieurs recherches ont été réalisées afin d’identifier les paramètres opérationnels des piles
aux ions lithium. Toutefois, la plupart de ces études ont porté sur l’estimation d’un nombre
limité de paramètres et se sont attardées sur un seul type de matériau pour l’électrode positive
utilisé dans la fabrication des piles Li-ion. De plus, le couplage qui existe entre les
paramètres électrochimiques et thermo-physiques est complètement ignoré. Le but principal
de cette thèse est de développer une méthode générale pour identifier simultanément
différents paramètres électrochimiques et thermo-physiques et de prédire la performance des
piles Li-ion à base de différents matériaux d’électrodes positives. Pour atteindre ce but, une
méthode inverse efficace a été introduite. Des modèles directs représentatifs des piles Li-ion
à base de différents matériaux d’électrodes positives ont également été développés. Un modèle rapide et précis simulant la performance de piles Li-ion avec des électrodes positives
à base de LiMn2O4 ou de LiCoO2 est présenté. Également, deux modèles ont été développés
pour prédire la performance des piles Li-ion avec une électrode positive de LiFePO4. Le
premier, appelé modèle mosaïque modifié (MM), est basé sur une approche macroscopique
alors que le deuxième, appelé le modèle mésoscopique, est plutôt basé sur une approche
microscopique. Des études d’estimation de paramètres ont été conduites en utilisant les
modèles développés et des données expérimentales fournies par Hydro-Québec. Tous les
paramètres électrochimiques et thermo-physiques des piles Li-ions ont été simultanément
identifiés et appliqués à la prédiction de la performance des piles. Finalement, une technique
en temps réel reposant sur des réseaux de neurones est introduite dans la méthode
d’estimation des paramètres intrinsèques au piles Li-ion.Abstract : The safety of many electrical systems is strongly dependent on the reliable operation of their lithium-ion (Li-ion) battery packs. As a result, the battery packs must be monitored by a battery management system (BMS). The BMS interacts with all the components of the system so as to maintain the integrity of the batteries. The main part of a BMS is a Li-ion battery model that simulates and predicts its different operating points. In the electronics and in the automobile industries, the BMS usually rests on simple empirical models. They are however unable to predict the battery parameters as it ages. Furthermore, they are only applicable to a specific cell. Electrochemical-based models are, on the other hand, more sophisticated and more precise. These models are based on chemical/electrochemical kinetics and transport equations. They may be used to simulate the Li-ion battery characteristics and reactions. In order to run the electrochemical-based mathematical models, it is imperative to know the different electrochemical and thermophysical parameters of the battery. The significant variables of the Li-ion battery can be classified into three groups: geometric, material and operational parameters. The geometric and material parameters can be easily obtained from direct measurements or from the datasheets provided by the manufacturer. The operational properties are, on the other hand, not easily available. Furthermore, some of them may vary according to the measurement techniques or the battery age. Sometimes, the measurement of these parameters requires the dismantling of the battery itself, which is a risky and destructive procedure. Many investigations have been conducted to identify the operational parameters of Li-ion batteries. However, most of these studies focused on the estimation of limited parameters, or considered only one type of the positive electrode materials used in Li-ion batteries. Moreover, the coupling of the thermophysical parameters to the electrochemical variables is ignored in all of them. The main goal of this thesis is to develop a general method to simultaneously identify different electrochemical and thermophysical parameters and to predict the performance of Li-ion batteries with different positive electrode materials. To achieve this goal, an effective inverse method is introduced. Also, direct models representative of Li-ion batteries are developed, applicable for all of the positive electrode materials. A fast and accurate model is presented for simulating the performance of the Li-ion batteries with the LiMn2O4 and LiCoO2 positive electrodes. Moreover, two macro- and micro-based models are developed for predicting the performance of Li-ion battery with the LiFePO4 positive electrode, namely the Modified Mosaic (MM) and the mesoscopic-based models. The parameter estimation studies are then implemented by means of the developed direct models and experimental data provided by Hydro-Québec. All electrochemical and thermophysical parameters of the Li-ion batteries are simultaneously identified and applied for the prediction of the battery performance. Finally, a real-time technique resting on neural networks is used for the estimation of the Li-ion batteries intrinsic parameters.
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Zhao, Wenjiao [Verfasser], and H. J. [Akademischer Betreuer] Seifert. "Thermal Characterization of Lithium-ion Cells with Positive Electrode Materials $LiNi_xMn_0.8-xCo_0.2O_2 and their Components / Wenjiao Zhao ; Betreuer: H. J. Seifert." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1238148034/34.
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Gabrielli, Giulio [Verfasser]. "Studies of high voltage LiNi0.5Mn1.5O4 as positive electrode material in lithium ion cells / Giulio Gabrielli." Ulm : Universität Ulm, 2017. http://d-nb.info/1124902651/34.
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Ukyo, Y., K. Horibuchi, H. Oka, H. Kondo, K. Tatsumi, S. Muto, and Y. Kojima. "Degradation analysis of a Ni-based layered positive-electrode active material cycled at elevated temperatures studied by scanning transmission electron microscopy and electron energy-loss spectroscopy." Elsevier, 2011. http://hdl.handle.net/2237/20821.
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Lemoine, Kévin. "Nouveaux matériaux fluorés d'électrodes positives à cations 3d mixtes pour batteries à ions lithium : Elaboration, caractérisation structurale et propriétés électrochimiques." Thesis, Le Mans, 2019. http://www.theses.fr/2019LEMA1030.
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Ce travail concerne l’application d'une stratégie de synthèse en deux étapes pour préparer de nouveaux matériaux fluorés à base de fer dans l’objectif de les tester en tant que composé actif d’électrodes positives pour batteries à ions lithium : élaboration d’un précurseur suivie d’un traitement thermique adéquat. L’étude porte dans un premier temps sur les fluorures hydratés 3D à valence mixte de fer, Fe2F5(H2O)2 de structure weberite inverse et Fe3F8(H2O)2. Par traitement thermique sous air, deux hydroxyfluorures sont stabilisés, FeF2.5(OH)0.5 de structure pyrochlore et FeF2.66(OH)0.34 de structure HTB respectivement. L’étude de leur comportement électrochimique montre d’excellentes capacités ≈ 170 mAh.g-1 (2-4 V). Afin d’étudier l'impact de la nature des cations 3d sur les performances, les hydrates équivalents à cations mixtes, M2+Fe3+F5(H2O)2 (M = Mn, Ni) et M2+M3+2F8(H2O)2 (M2+ = Mn, Fe, Co, Ni, Cu ; M3+ = V, Fe), ont été synthétisés en milieu solvothermal dans une seconde partie. Des intermédiaires amorphes oxyfluorés apparaissent lors de la dégradation thermique sous air avec en particulier CuFe2F6O, obtenu à partir de CuFe2F8(H2O)2, qui présente une capacité remarquable de 310 mAh.g-1 (2-4 V). Enfin, des fluorures d’ammonium à cations mixtes NH4M2+Fe3+F6 (M = Mn, Co, Ni, Cu), obtenus par mécanosynthèse et la voie solvothermale, ont conduit aux premiers fluorures à cations mixtes trivalents M0.5Fe0.5F3 (M = Mn, Co, Ni, Cu) de structure pyrochlore par oxydation topotactique sous fluor moléculaire F2 en températureThis work presents an innovative synthetic strategy to develop new fluorinated iron-based materials as positive electrodes for Li-ion batteries. This two-step elaboration method consists in the preparation of fluorinated precursors followed by an appropriate thermal treatment. The study initially focuses on tridimensional mixed valence iron fluorides, Fe2F5(H2O)2 with the inverse weberitestructural type and Fe3F8(H2O)2. The calcination under air leads to the formation of two new hydroxyfluorides, FeF2.5(OH)0.5 and FeF2.66(OH)0.34 with pyrochlore and HTB structural types respectively which present excellent electrochemical capacities ≈ 170 mAh.g-1 (2-4 V). In a second part, the 3d-cation effect on oxyfluorides performances is evaluated from equivalent mixed metal cation hydrates, M2+Fe3+F5(H2O)2 (M = Mn, Ni) and M2+M3+2F8(H2O)2 (M2+ = Mn, Fe, Co, Ni, Cu, M3+ = V, Fe), synthesized solvothermally. Their thermal degradation under air reveals amorphous oxyfluorinated intermediates and among them, CuFe2F6O, obtained from CuFe2F8(H2O)2, with an remarkable capacity of 310 mAh.g-1 (2-4 V). In the last part, mixed ammonium fluorides (NH4)M2+Fe3+F6 (M = Mn, Co, Ni, Cu) are synthesized using mechanochemical and solvothermal routes. Their thermal topotactic oxidation under molecular fluorine F2 leads to the first trivalent mixed-cation fluorides M0.5Fe0.5F3 (M = Mn, Co, Ni, Cu) with pyrochlore typestructure
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Kifune, Koichi, Miho Fujita, Mitsuru Sano, Motoharu Saitoh, and Koh Takahashi. "Electrochemical and Structural Properties of a 4.7 V-Class LiNi0.5Mn1.5 O 4 Positive Electrode Material Prepared with a Self-Reaction Method." The Electrochemical Society, 2004. http://hdl.handle.net/2237/18424.
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Mortemard, de boisse Benoit. "Etudes structurales et électrochimiques des matériaux NaxMn1-yFeyO2 et NaNiO2 en tant qu’électrode positive de batteries Na-ion." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0370/document.
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Ce travail présente les études électrochimiques et structurales menées sur deux systèmes : P2/O3-NaxMn1-yFeyO2 et O’3-NaxNiO2 utilisés en tant que matériaux d’électrode positive pour batteries Na-ion.Concernant le système P2/O3-NaxMn1-yFeyO2, l’étude par diffraction des rayons X menée in situ pendantla charge de batteries a montré de nombreuses transitions structurales. Que leur structure soit de type P2ou O3, les matériaux présentent une phase distordue pour les taux d’intercalation (x) les plus élevés etune phase très peu ordonnée pour les taux d’intercalation les moins élevés. Entre ces deux étatsd’intercalation, les phases de type P2 présentent moins de transitions que les phases de type O3. Celaentraine de meilleures propriétés électrochimiques pour les phases de type P2 (meilleure capacité endécharge, meilleure rétention de capacité…). Les spectroscopies d’absorption des rayons X et Mössbauerdu 57Fe ont montré que les couples redox Mn4+/Mn3+ et Fe4+/Fe3+ sont impliqués lors du cyclage, à bas ethaut potentiel, respectivement.Concernant O’3-NaNiO2, la diffraction des rayons-X menée in situ pendant la charge de batteriesO’3-NaNiO2//Na a montré de nombreuses transitions structurales O’3 ↔ P’3 résultant du glissement desfeuillets MO2. Ces transitions s’accompagnent de mises en ordre Na+ - lacunes dans le matériau. La tailledes grains a montré avoir un intérêt majeur puisqu’elle influe sur le nombre de phases présentessimultanément dans le matériau. Lorsque la batterie est déchargée, la phase limitante Na≈0.8NiO2 estobservée et empêche le retour à O’3-NaNiO2This work concerns the electrochemical and structural studies carried out on two systems used aspositive electrode materials for Na-ion batteries: P2/O3-NaxMn1-yFeyO2 and O’3-NaxNiO2. Concerning theP2/O3-NaxMn1-yFeyO2 systems, in situ X-ray diffraction carried out during the charge of the batteriesshowed that both materials undergo several structural transitions. Both the P2 and O3 phases show adistorted phase for the higher intercalation rates (x) and a poorly ordered phase for the lower ones.Between these two states, P2-based materials exhibit less structural transitions than the O3-based ones.This is correlated to the better electrochemical properties the P2-based materials exhibit (better dischargecapacity, better capacity retention…). X-ray absorption and 57Fe Mössbauer spectroscopies showed thatthe Mn4+/Mn3+ and Fe4+/Fe3+ redox couples are active upon cycling, respectively at low and high voltage.Concerning O’3-NaNiO2, in situ X-ray diffraction carried out during the charge of O’3-NaNiO2//Nabatteries showed several structural transition between O’3 and P’3 structures, resulting from slab glidings.These transitions are accompanied by Na+ - vacancies ordering within the “NaO6” slabs. Upon discharge,the material does not come back to its initial state and, instead, the Na≈0.8NiO2 phase represents themaximum intercalated state. The occurrence of this limiting phase prevents O’3-NaNiO2 to be consideredas an interesting material for real Na-ion applications
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Schmidt, Elisabeth. "Elaboration et caractérisation de couches minces amorphes d'oxysulfures de molybdène utilisables comme électrode positive dans des générateurs électrochimiques." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00134070.
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Des couches minces amorphes d'oxysulfures de molybdène, préparées par pulvérisation cathodique radiofréquence, ont ete caractérisées par spectroscopie AUGER, RBS, microsonde électronique, diffraction des rayons X et diffraction électronique. Une étude XPS a permis de déterminer le degré d'oxydation et l'environnement des différents éléments en fonction de la composition des couches minces. Les propriétés électrochimiques de ces nouveaux matériaux ont été déterminees. Ils ont été utilisés comme électrode positive dans des générateurs électrochimiques au lithium. Un grand nombre de cycles décharge-charge a été réalisé. Il a été montre que le soufre et le molybdène participent aux mécanismes d'oxydoréduction.
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Masoumi, Maryam [Verfasser], and Seifert H. [Akademischer Betreuer] J. "Thermochemical and electrochemical investigations of Li(Ni,Mn,Co)O$_2}$ (NMC) as positive electrode material for lithium-ion batteries / Maryam Masoumi ; Betreuer: H. J. Seifert." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1223027961/34.
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Reynaud, Marine. "Elaboration de nouveaux matériaux à base de sulfates pour l'électrode positive des batteries à ions Li et Na." Phd thesis, Université de Picardie Jules Verne, 2013. http://tel.archives-ouvertes.fr/tel-01018912.
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Les prochaines générations de batteries à ions lithium et sodium seront basées sur le développement de nouveaux matériaux d'électrode positive durables, peu chers et sûrs. Dans ce but, nous avons exploré le monde des minéraux à la recherche de structures présentant les pré-requis pour l'insertion et la désinsertion d'ions alcalins. Nous avons alors entrepris l'étude de sulfates bimétalliques dérivés du minéral bloedite, ayant pour formule générale AxM(SO4)2*nH2O (A = Li, Na, M = métal de transition 3d, et n = 0, 4). Ces systèmes présentent une cristallochimie riche, montrant des transitions structurales en fonction de la température ainsi qu'avec le départ des molécules d'eau. Les nouvelles structures ont été déterminées en combinant les techniques de diffraction des rayons X, neutrons et électrons. Nous avons également montré que les composés à base de lithium LixM(SO4)2 présentent des propriétés antiferromagnétiques intéressantes, du fait notamment de leurs structures particulières qui permettent seulement des interactions de super-super-échange. Enfin et surtout, nous avons, parmi les composés isolés, identifié trois sulfates à base de fer, à savoir Na2Fe(SO4)2*4H2O, Na2Fe(SO4)2 et Li2Fe(SO4)2, qui présentent des propriétés électrochimiques intéressantes face au lithium et au sodium. Avec un potentiel de 3,83 V vs. Li+/Li0, la nouvelle phase marinite Li2Fe(SO4)2 affiche le plus haut potentiel jamais observé pour le couple redox FeIII+/FeII+ dans un composé inorganique à base de fer et dépourvu de fluor, et est en fait seulement dépassé par celui de la forme triplite de LiFeSO4F.
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Řehák, Petr. "Studium vlivu modifikace separátorů na vlastnosti Li-S akumulátorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442444.
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This thesis deals with the development and current issues of Li-ion and Li-S accumulators, especially the separators. In the theoretical part is described history of Li-ion batteries, their properties and materials for the positive electrode. Li-S batteries and their problems are also described in this diploma thesis. In the practical part, electrochemical methods were described, and several separator samples with various modifications were created. These samples were then photographed using an SEM electron microscope and evaluated using electrochemical methods.
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Foltová, Anežka. "Vliv tlaku použitého při výrobě elektrod na jejich výsledné vlastnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-319628.
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The aim of this work is to describe final properties of the electrodes based on the amount of pressure used during its production. In the theoretical part of this work, secondary electrochemical accumulators are described, with the focus on Li-ion accumulators. In the main part of this work, the production of Li-ion accumulators, with usage of different pressures during its production is described. In the final part of this work, the examination of these created cells for the classification of the optimal production pressure is described.
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Tavener, P. "Electron spectroscopy of electrode materials." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370304.
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Xiao, Lei. "Nano-electrode materials for electroanalysis." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526413.
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Thomas, Glyn Rees. "Counter electrode materials for electrochromic windows." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261513.
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Malmberg, Helena. "Nanoscientific investigations of electrode materials for supercapacitors." Doctoral thesis, Stockholm : Kemiteknik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4508.
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Friedrich, Jens Maximilian. "Characterisation of electrode materials for electrochemical reactors." Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435749.
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Lazzari, Mariachiara <1978>. "Electrode Materials for Ionic Liquid Based-Supercapacitors." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2718/.
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The development of safe, high energy and power electrochemical energy-conversion systems can be a response to the worldwide demand for a clean and low-fuel-consuming transport. This thesis work, starting from a basic studies on the ionic liquid (IL) electrolytes and carbon electrodes and concluding with tests on large-size IL-based supercapacitor prototypes demonstrated that the IL-based asymmetric configuration (AEDLCs) is a powerful strategy to develop safe, high-energy supercapacitors that might compete with lithium-ion batteries in power assist-hybrid electric vehicles (HEVs). The increase of specific energy in EDLCs was achieved following three routes: i) the use of hydrophobic ionic liquids (ILs) as electrolytes; ii) the design and preparation of carbon electrode materials of tailored morphology and surface chemistry to feature high capacitance response in IL and iii) the asymmetric double-layer carbon supercapacitor configuration (AEDLC) which consists of assembling the supercapacitor with different carbon loadings at the two electrodes in order to exploit the wide electrochemical stability window (ESW) of IL and to reach high maximum cell voltage (Vmax).
Among the various ILs investigated the N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR1(2O1)TFSI) was selected because of its hydrophobicity and high thermal stability up to 350 °C together with good conductivity and wide ESW, exploitable in a wide temperature range, below 0°C. For such exceptional properties PYR1(2O1)TFSI was used for the whole study to develop large size IL-based carbon supercapacitor prototype.
This work also highlights that the use of ILs determines different chemical-physical properties at the interface electrode/electrolyte with respect to that formed by conventional electrolytes. Indeed, the absence of solvent in ILs makes the properties of the interface not mediated by the solvent and, thus, the dielectric constant and double-layer thickness strictly depend on the chemistry of the IL ions.
The study of carbon electrode materials evidences several factors that have to be taken into account for designing performing carbon electrodes in IL. The heat-treatment in inert atmosphere of the activated carbon AC which gave ACT carbon featuring ca. 100 F/g in IL demonstrated the importance of surface chemistry in the capacitive response of the carbons in hydrophobic ILs. The tailored mesoporosity of the xerogel carbons is a key parameter to achieve high capacitance response. The CO2-treated xerogel carbon X3a featured a high specific capacitance of 120 F/g in PYR14TFSI, however, exhibiting high pore volume, an excess of IL is required to fill the pores with respect to that necessary for the charge-discharge process. Further advances were achieved with electrodes based on the disordered template carbon DTC7 with pore size distribution centred at 2.7 nm which featured a notably high specific capacitance of 140 F/g in PYR14TFSI and a moderate pore volume, V>1.5 nm of 0.70 cm3/g.
This thesis work demonstrated that by means of the asymmetric configuration (AEDLC) it was possible to reach high cell voltage up to 3.9 V. Indeed, IL-based AEDLCs with the X3a or ACT carbon electrodes exhibited specific energy and power of ca. 30 Wh/kg and 10 kW/kg, respectively. The DTC7 carbon electrodes, featuring a capacitance response higher of 20%-40% than those of X3a and ACT, respectively, enabled the development of a PYR14TFSI-based AEDLC with specific energy and power of 47 Wh/kg and 13 kW/kg at 60°C with Vmax of 3.9 V.
Given the availability of the ACT carbon (obtained from a commercial material), the PYR1(2O1)TFSI-based AEDLCs assembled with ACT carbon electrodes were selected within the EU ILHYPOS project for the development of large-size prototypes. This study demonstrated that PYR1(2O1)TFSI-based AEDLC can operate between -30°C and +60°C and its cycling stability was proved at 60°C up to 27,000 cycles with high Vmax up to 3.8 V. Such AEDLC was further investigated following USABC and DOE FreedomCAR reference protocols for HEV to evaluate its dynamic pulse-power and energy features. It was demonstrated that with Vmax of 3.7 V at T> 30 °C the challenging energy and power targets stated by DOE for power-assist HEVs, and at T> 0 °C the standards for the 12V-TSS and 42V-FSS and TPA 2s-pulse applications are satisfied, if the ratio wmodule/wSC = 2 is accomplished, which, however, is a very demanding condition.
Finally, suggestions for further advances in IL-based AEDLC performance were found. Particularly, given that the main contribution to the ESR is the electrode charging resistance, which in turn is affected by the ionic resistance in the pores that is also modulated by pore length, the pore geometry is a key parameter in carbon design not only because it defines the carbon surface but also because it can differentially “amplify” the effect of IL conductivity on the electrode charging-discharging process and, thus, supercapacitor time constant.
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Hao, Yong. "Sulfur Based Electrode Materials For Secondary Batteries." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2582.
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Developing next generation secondary batteries has attracted much attention in recent years due to the increasing demand of high energy and high power density energy storage for portable electronics, electric vehicles and renewable sources of energy. This dissertation investigates sulfur based advanced electrode materials in Lithium/Sodium batteries. The electrochemical performances of the electrode materials have been enhanced due to their unique nano structures as well as the formation of novel composites.
First, a nitrogen-doped graphene nanosheets/sulfur (NGNSs/S) composite was synthesized via a facile chemical reaction deposition. In this composite, NGNSs were employed as a conductive host to entrap S/polysulfides in the cathode part. The NGNSs/S composite delivered an initial discharge capacity of 856.7 mAh g-1 and a reversible capacity of 319.3 mAh g-1 at 0.1C with good recoverable rate capability.
Second, NGNS/S nanocomposites, synthesized using chemical reaction-deposition method and low temperature heat treatment, were further studied as active cathode materials for room temperature Na-S batteries. Both high loading composite with 86% gamma-S8 and low loading composite with 25% gamma-S8 have been electrochemically evaluated and compared with both NGNS and S control electrodes. It was found that low loading NGNS/S composite exhibited better electrochemical performance with specific capacity of 110 and 48 mAh g-1 at 0.1C at the 1st and 300th cycle, respectively. The Coulombic efficiency of 100% was obtained at the 300th cycle.
Third, high purity rock-salt (RS), zinc-blende (ZB) and wurtzite (WZ) MnS nanocrystals with different morphologies were successfully synthesized via a facile solvothermal method. RS-, ZB- and WZ-MnS electrodes showed the capacities of 232.5 mAh g-1, 287.9 mAh g-1 and 79.8 mAh g-1 at the 600th cycle, respectively. ZB-MnS displayed the best performance in terms of specific capacity and cyclability. Interestingly, MnS electrodes exhibited an unusual phenomenon of capacity increase upon cycling which was ascribed to the decreased cell resistance and enhanced interfacial charge storage.
In summary, this dissertation provides investigation of sulfur based electrode materials with sulfur/N-doped graphene composites and MnS nanocrystals. Their electrochemical performances have been evaluated and discussed. The understanding of their reaction mechanisms and electrochemical enhancement could make progress on development of secondary batteries.
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Blanchard, Rémi. "Redox shuttle and positive electrode protection for Li-O2 systems." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI098/document.
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Les travaux de cette thèse focalisent sur la résolution de deux problèmes majeurs des électrodes positives de systèmes Li-O2, dus à la nature du produit de décharge formé pendant la réaction de réduction de l'oxygène, en milieux Li+ : Lithium peroxyde (Li2O2). Le premier problème est lié au processus de formation de ce dernier (étapes successives de nucléation électrochimiques et de dismutation chimique d'un intermédiaire : le superoxide de lithium), qui conduit à la formation de très grosses particules de peroxyde lithium à la surface de l'électrode. Du fait de leurs taille et de leur résistivité ( le gap du peroxyde de lithium est de 5 eV), il est impossible de recharger de manière efficace et à 100% ce dernier. Cependant, ce problème peut être résolu, grâce à l'ajout d'un additif, qui permet le transport d'électron en solution, et qui peut (en théorie), recharger les particules de Li2O2, détachées de l'électrode. Un très bon candidat a été trouvé dans cette étude, qui a prouvé de très bonne performances pour l'amélioration du processus de recharge, et un effet bénéfique supplémentaire a été caractérisé sur le potentiel de décharge, grâce à un effet catalytique (augmentation du potentiel de réduction de 230 mV). Cependant, cette solution demande de repenser totalement le design actuel des systèmes Li-O2, car ce composé (soluble) peut facilement traverser le séparateur, vers l'électrode de lithium (et causer une autodécharge importante ainsi qu'une boucle de recharge infinie). Le second problème est lié à une autre caractéristique du peroxyde de lithium : sa réactivité. De fait, c'est un base forte au sens de Lewis (en accord avec la théorie HSAB), et réagit de manière importante avec les constituants de l'électrodes (réactivité avec le liant PVDF, mais aussi avec les solvant, le sel et le support carboné de l'électrode). Il est donc nécessaire de trouver un moyen de protéger ce dernier, et une solution proposé dans ce manuscrit a été de réaliser la déposition d'une couche nanométrique de Nb2O5, qui a pour but d'éviter tout contact direct entre le carbone, et le peroxyde de lithium (réaction entre ces deux derniers, qui conduit à la formation d'un composé avec un gap de 7 eV : le carbonate de lithium). Le dépôt fut étudié sur un carbone graphitisé (Zoltek Panex 30) qui, de manière surprenante, a été très résistant versus le peroxyde de lithium. Malheureusement, la présence du dépôt à la surface du tissus n'a pas protégé l'électrode, mais a plutôt eu l'effet inverse, car des traceurs de la formation de carbonate de lithium ont pu être observé (alors qu'aucun traceur n'était détecté sur le tissu nu). Le Nb2O5 a donc été écarté, et d'autres composés doivent être testés dans de futures études, pour cette applicationThe present PhD work focuses on solving two major issues of the Li-O2 positive electrodes, both being linked with the nature of the discharge product formed during the Oxygen Reduction Reaction, in Lithium cation electrolyte: Lithium peroxide (Li2O2). The first issue is related to the Discharge mechanism (consecutives Electrochemical nucleation and chemical disproportionation of an intermediate, lithium superoxide), which lead to the formation of large particles of lithium peroxide on the electrode surface. Owing to their size and resistivity (bandgap of lithium peroxide : 5 eV), it is nearly impossible to re-charge efficiently the electrode. This issue can be solved, thanks to the dissolution of an additive in solution, that promote the transport of electrons, and allow the oxidation of large discharge particles (in theory, even the ones disconnected from the electrode). A very good compound was found to efficiently work as a redox shuttle (enhanced Oxygen Evolution reaction), with also a highly beneficial effect for the ORR, with a catalysis effect that allowed to increase the onset of the ORR of 230 mV. However, this solution require a engineering of the practical system as this additive could cross from the positive electrode to the negative side (lithium) and trigger capacity loss and infinite charging loop. The second issue is linked to its reactivity. As a matter of fact, it is an hard base (according to HSAB theory), which reacts readily with a large panel of electrodes component (reactivity toward the PvDf binder, solvent, salts, but also with the carbon material, used as the positive electrode). As such, it is necessary to find a way to protect the latter, and a solution proposed in this work was to use Atomic Layer deposition of Niobium pentoxide (Nb2O5), in order to form a very thin deposit, which was supposed to prevent any contact between the discharge product, and the carbon support (consumption of Carbon, with formation of a large bandgap compound : Lithium carbonate). The deposition was conducted onto a graphitized carbon cloth (Zoltek Panex 30), which surprisingly proved to be highly resistant toward lithium peroxide. Sadly, the presence of the deposit did not protect the electrode but rather made it weaker, with tracers of the formation lithium carbonate. This compound was thus not considered anymore, and others deposits are yet needed to be tested in future studies
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Yamada, Izumi. "Studies on Litihum Ion Transfer at Positive-electrode/Electrolyte Interface." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/77798.
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Lao, Zhuo Jin. "Metal oxides as electrode materials for electrochemical capacitors." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060726.101327/index.html.
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Berrigan, John Daniel. "Biomimetic and synthetic syntheses of nanostructured electrode materials." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/53143.
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The scalable syntheses of functional, porous nanostructures with tunable three-dimensional morphologies is a significant challenge with potential applications in chemical, electrical, electrochemical, optical, photochemical, and biochemical devices. As a result, several bio-enabled and synthetic approaches are explored in this work (with an emphasis on peptide-enabled deposition) for the generation of aligned nanotubes of nanostructured titania for application as electrodes in dye-sensitized solar cells and biofuel cells. As part of this work, peptide-enabled deposition was used to deposit conformal titania coatings onto porous anodic alumina templates under ambient conditions and near-neutral pH to generate aligned, porous-wall titania nanotube arrays that can be integrated into dye-sensitized solar cells where the arrays displayed improved functional dye loading compared to sol-gel-derived nanotubes. A detailed comparison between synthetic and bioorganic polyamines with respect to titania film properties deposition rate provided valuable information for future titania coating experimental design given specific applications. The development of template-based approaches to single-wall titania nanotube arrays led to the development of a new synthetic method to create aligned, multi-walled titania nanotube arrays. Lastly, peptide-enabled deposition methods were extended beyond inorganic mineral and used for enzyme immobilization by cross-linking the peptide with the multicopper oxidase laccase. Peptide-laccase hybrid enzyme coatings improved both the amount of enzyme adsorbed onto carbon nanotube “buckypaper” and allowed the enzyme to retain more activity upon immobilization onto the surface.
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Dijk, Nicholas van. "Rapid prototyping of electrode materials for fuel cells." Thesis, Loughborough University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443957.
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Cooper, Benjamin D. "Electrode materials for the electrolysis of metal oxides." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35072.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, June 2006."May 2006."
Includes bibliographical references (leaves 35-36).
Carbon, tungsten, platinum, and iridium were examined as candidate anode materials for an electrolytic cell. The materials were pre-selected to endure high process temperatures and were characterized for inertness and high current density during electrolysis using voltammometric techniques. Inertness is viewable through current discrepancies dependent on voltage scan direction at low voltage, consumption of current by metal oxide formation, and ease of surface oxide electro-stripping. Conductivity during electrolytic oxidation is observable as current density maximization at high voltages. While carbon, tungsten, and platinum formed surface oxides, iridium remained quite inert. In addition, the voltage hold-time was found to affect the leading current density, as platinum performed best during cyclic voltammometry, but iridium performed best during potentiostatic electrolysis. The intermediate potentiodynamic scan-rate displays the transition from platinum to iridium dominated current density.
by Benjamin D. Cooper.
S.B.
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Lyness, Christopher. "Novel lithium-ion host materials for electrode applications." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1921.
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Two novel lithium host materials were investigated using structural and electrochemical analysis; the cathode material Li₂CoSiO₄ and the LiMO₂ class of anodes (where M is a transition metal ion). Li₂CoSiO₄ materials were produced utilising a combination of solid state and hydrothermal synthesis conditions. Three Li₂CoSiO₄ polymorphs were synthesised; β[subscript(I)], β[subscript(II)] and γ₀. The Li₂CoSiO₄ polymorphs formed structures based around a distorted Li₃PO₄ structure. The β[subscript(II)] material was indexed to a Pmn2₁ space group, the β[subscript(I)] polymorph to Pbn2₁ and the γ₀ material was indexed to the P2₁/n space group. A varying degree of cation mixing between lithium and cobalt sites was observed across the polymorphs. The β[subscript(II)] polymorph produced 210mAh/g of capacity on first charge, with a first discharge capacity of 67mAh/g. It was found that the β[subscript(I)] material converted to the β[subscript(II)] polymorph during first charge. The γ₀ polymorph showed almost negligible electrochemical performance. Capacity retention of all polymorphs was poor, diminishing significantly by the tenth cycle. The effect of mechanical milling and carbon coating upon β[subscript(II)], β[subscript(I)] and γ₀ materials was also investigated. Various Li[subscript(1+x)]V[subscript(1-x)]O₂ materials (where 0≤X≤0.2) were produced through solid state synthesis. LiVO₂ was found to convert to Li₂VO₂ on discharge, this process was found to be strongly dependent on the amount of excess lithium in the system. The Li₁.₀₈V₀.₉₂O₂ material had the highest first discharge capacity at 310mAh/g. It was found that the initial discharge consisted of several distinct electrochemical processes, connected by a complicated relationship, with significant irreversible capacity on first discharge. Several other LiMO₂ systems were investigated for their ability to convert to layered Li₂MO₂ structures on low voltage discharge. While LiCoO₂ failed to convert to a Li₂CoO₂ structure, LiMn₀.₅Ni₀.₅O₂ underwent an addition type reaction to form Li₂Mn₀.₅Ni₀.₅O₂. A previously unknown Li₂Ni[subscript(X)]Co[subscript(1-X)]O₂ structure was observed, identified during the discharge of LiNi₀.₃₃Co₀.₆₆O₂.
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Li, Da. "New advanced electrode materials for lithium-ion battery." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/15601.
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This thesis includes five main studies/ first, in order to enhance the conductivity of LiTi204, a new doping strategy is used and LiTi204−xCx ramsdellite is successfully fabricated. It is found that unit cell parameters a and b decline while c increases with more carbon inserted. The conductivity of LiTi204−xCx increases with more carbon insertion. Material with more carbon shows better reversibility and lower electrochemical polarization observed from potentiostatic curve. The material has better retention rate and rate ability with more carbon substitute doped. LiTi203.925C0.0375 has 151 mAh∙g−1 capacity under current density of 100 mAh∙g−1 and capacity decreased by 5.57% after 100 cycles. Second, in order to improve the capacity of LiTi204−xCx, Ti204−xCx is successfully fabricated through topotactic oxidation. It is found that the lattice parameters b and c decline while a keeps stable. With more carbon inserted, the retention ability increases. Ti01.9625C0.0375 has the capacity 320 mAh∙g−1 under 200 mAh∙g−1 and capacity retention loss by 9.1% per 100 cycles due to the balance of high conductivity and disordered channel resistance. Third, in order to study the process of lithium insertion, the structures and the atom sites of LiTi204−xCx ( R ) are obtained through refinement of the neutron diffraction patterns. The unit cell parameters a and b increase while c keeps stable for more lithium, atoms insertion. The channels for lithium insertion become wider and more round with lithium arranged in a line when x rises in the range of 0 < x < 0.5. When the x increases to 1, the channels turn into ordered parallelogram. Fourth, the lithium-contained spinelloid (a potential cathode material) is explored, but it is not found in this work. But spinels LI1−0.5xFe2.5xM1−xP1−xO4 (M=Fe, Co, Ni, Mn) are found and phosphorous insertion makes the structure stable during cycling. At last, to enhance the energy density, the 3D electrode is fabricated in in-situ growth by infiltration method. By powder infiltration, the load of activity material reaches over 60% of electrode mass. The morphology is porous and the particle size of the activity material is 20nm. The energy density based on LiCoO2 (250 WH∙g−1) is much higher than that of the traditional (200 WH∙g−1) 2D electrode reported.
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Gillard, Stephen Paul. "Environmental electrochemistry : reactor design, electrode materials and process monitoring." Thesis, University of Portsmouth, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407225.
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Minett, Michael Geoffrey. "New composite insertion electrode materials for secondary lithium cells." Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327916.
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Perkins, Mark James. "Carbon-based negative electrode materials for rechargeable lithium batteries." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326801.
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Du, Dongwei. "Development of advanced electrode materials for high-performance supercapacitors." Thesis, University of Warwick, 2018. http://wrap.warwick.ac.uk/108878/.
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The demand for high-performance electrochemical energy storage devices is ever-growing as they are critical components for portable electronics, electric vehicles, and efficient storage media for energy from renewable sources. Electrochemical capacitors (also called supercapacitors) are emerging as one of the most promising candidates due to their rapid charge rate, high power density, good rate capability and excellent lifespan. However, their usage is significantly limited by the disadvantages of low energy density. The main aim of this work is to develop advanced electrode materials for supercapacitors with improved energy density while maintaining high power density and long cycle life. In this thesis, we have developed four novel electrode materials based on the transition metals of Ni and Cu for supercapacitor applications, including the metal oxides (Li2Ni2(MoO4)3 and Cu2O/CuMoO4) and metal sulfides (NiMoS4-A and Ni-Cu-S). These materials were prepared via different techniques, such as combustion, chemical co-precipitation and hydrothermal. Their physical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) etc. Their electrochemical behaviours were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and cycling stability etc. To further measure the performance in practical energy storage devices, the materials were tested with a two-electrode configuration. All the four materials were used as positive electrodes, which were paired with proper activated carbon (AC) or nitrogen-doped graphene (NG) negative electrodes to assemble asymmetric supercapacitors (ASCs). At a current density of 1 A g-1, the Cu2O/CuMoO4 electrode exhibits a high specific capacitance of 4264 F g-1, superior to the1137 F g-1 of the Li2Ni2(MoO4)3, 706.5 F g-1 of the NiMoS4-A, and 938.6 F g-1 of the Ni-Cu-S. In terms of the ASCs, the Cu2O/CuMoO4//AC ASC could expand the operation voltage to 1.7 V, at which the energy density can reach 75.1 Wh kg-1 with a power density of 420 W kg-1. The NiMoS4-A//AC ASC displays a high energy density of 35 Wh kg-1 at an average power density of 400 W kg-1. Meanwhile, it exhibits excellent cycle stability, maintaining 82% of the initial capacitance after 10000 charge-discharge cycles at 5 A g-1. These good results suggest that the developed materials are promising for high-performance supercapacitor applications.
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Stjerndahl, Mårten. "Stability Phenomena in Novel Electrode Materials for Lithium-ion Batteries." Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8214.
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Li-ion batteries are not only a technology for the future, they are indeed already the technology of choice for today’s mobile phones, laptops and cordless power tools. Their ability to provide high energy densities inexpensively and in a way which conforms to modern environmental standards is constantly opening up new markets for these batteries. To be able to maintain this trend, it is imperative that all issues which relate safety to performance be studied in the greatest detail. The surface chemistry of the electrode-electrolyte interfaces is intrinsically crucial to Li-ion battery performance and safety. Unfortunately, the reactions occurring at these interfaces are still poorly understood. The aim of this thesis is therefore to increase our understanding of the surface chemistries and stability phenomena at the electrode-electrolyte interfaces for three novel Li-ion battery electrode materials.
Photoelectron spectroscopy has been used to study the surface chemistry of the anode material AlSb and the cathode materials LiFePO4 and Li2FeSiO4. The cathode materials were both carbon-coated to improve inter-particle contact. The surface chemistry of these electrodes has been investigated in relation to their electrochemical performance and X-ray diffraction obtained structural results. Surface film formation and degradation reactions are also discussed.
For AlSb, it has been shown that most of the surface layer deposition occurs between 0.50 and 0.01 V vs. Li°/Li+ and that cycling performance improves when the lower cut-off potential of 0.50 V is used instead of 0.01 V. For both LiFePO4 and Li2FeSiO4, the surface layer has been found to be very thin and does not provide complete surface coverage. Li2CO3 was also found on the surface of Li2FeSiO4 on exposure to air; this was found to disappear from the surface in a PC-based electrolyte. These results combine to give the promise of good long-term cycling with increased performance and safety for all three electrode materials studied.
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Jacas, Biendicho Jordi. "Impedance characterisation of different electrode materials for lithium-ion batteries." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531235.
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Wood, Stephen. "Computer modelling studies of new electrode materials for rechargeable batteries." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687357.
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Developing a sustainable energy infrastructure for the 21st century requires the large scale development of renewable energy resources. Fully exploiting these inherently intermittent supplies will require advanced energy storage technologies, with rechargeable Li-ion and Na-ion batteries considered highly promising for both vehicle electrification and grid storage applications. However, the performance required of battery materials has not been achieved, and significant improvements are needed. Modern computational techniques allow the elucidation of structure-property relationships at the atomic level and are valuable tools in providing fundamental insights into novel materials. Therefore, in this thesis a combination of atomistic simulation and ab initio density functional theory (DFT) techniques have been used to study a number of potential battery cathode materials. Firstly, Na2FePO4F and NaFePO4 are interesting materials that have been reported recently as attractive positive electrodes for Na-ion batteries. Here, we report their Na-ion conduction behaviour and intrinsic defect properties using atomistic simulation methods. Na+ ion conduction in Na2FePO4F is predicted to be two-dimensional (2D) in the interlayer plane. Na ion migration in NaFePO4 is restricted to the [010] direction along a curved trajectory, leading to quasi-1D Na+ diffusion. Furthermore, Na/Fe antisite defects are predicted to have a lower formation energy in NaFePO4 than Na2FePO4F. The higher probability of tunnel occupation with a relatively immobile Fe2+ cation - along with a greater volume change on redox cycling - contributes to the poor electrochemical performance of NaFePO4. Secondly, work on the Na2FePO4F system is extended to include investigation of the surface structures and energetics. The equilibrium morphology is found to be essentially octagonal, compressed slightly along the [010] direction, and is dominated by the (010), (021), (122) and (110) surfaces. The calculated growth morphology is a more ``rod-like'' nanoparticle, with the (021), (023), (110) and (112) planes predominant. The (010) surface lies parallel to the Na layers in the ac plane and is unlikely to facilitate Na+ intercalation. As such, its prominence in the equilibrium morphology, and absence from the growth morphology, suggests nanoparticles synthesised in a kinetically limited regime should provide higher rate performance than those synthesised in close to equilibrium conditions. Surface redox potentials for Na2FePO4F derived using DFT vary between 2.76 - 3.37 V, in comparison to a calculated bulk cell voltage of 2.91 V. Most significantly, the lowest energy potentials are found for the (130) and (001) planes suggesting that upon charging Na+ will first be extracted from these surfaces, and inserted lastly upon discharging. Thirdly, the mixed phosphates Na4M3(PO4)2P2O7 (M=Fe, Mn, Co, Ni) are explored as a fascinating new class of materials reported to be attractive Na-ion cathodes, displaying low volume changes upon cycling indicative of long lifetime operation. Key issues surrounding intrinsic defects, Na-ion migration mechanisms and voltage trends have been investigated through a combination of atomistic energy minimisation, molecular dynamics and DFT simulations. The MD results suggest Na+ diffusion extends across a 3D network of migration pathways with an activation barrier of 0.20-0.24 eV, and diffusion coefficients (DNa) of 10-10-10-11 cm2s-1 at 325 K, suggesting high rate capability. The cell voltage trends, explored using DFT methods, indicate that doping the Fe-based cathode with Ni can significantly increase the voltage, and hence energy density. Finally, DFT simulations of K+-stabilised α-MnO2 have been combined with aberration corrected-STEM techniques to study the surface energetics, particle morphologies and growth mechanism. α-K0.25MnO2 grown through a hydrothermal synthesis method is found to produce primary nanowires with preferential growth along the [001] direction. Primary nanowires attach through a shared (110) interface to form larger secondary nanowires. This is in agreement with DFT simulations with the {100}, {110} and {211} surfaces displaying the lowest surface energies. The ranking of surface energies is driven by Mn coordination environments and surface relaxation. The calculated equilibrium morphology of α-K0.25MnO2 is consistent with the observed primary nanowires from high resolution electron microscopy images.
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Toumar, Alexandra Jeanne. "Phase transformations in layered electrode materials for sodium ion batteries." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111255.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 118-130).
In this thesis, I investigate sodium ion intercalation in layered electrode materials for sodium ion batteries. Layered metal oxides have been at the forefront of rechargeable lithium ion battery technology for decades, and are currently the state of the art materials for sodium ion battery cathodes in line for commercialization. Sodium ion intercalated layered oxides exist in several different host phases depending on sodium content and temperature at synthesis. Unlike their lithium ion counterparts, seven first row layered TM oxides can intercalate Na ions reversibly. Their voltage curves indicate significant and numerous reversible phase transformations during electrochemical cycling. These transformations arise from Na-ion vacancy ordering and metal oxide slab glide but are not well understood and difficult to characterize experimentally. In this thesis, I explain the nature of these lattice differences and phase transformations for O and P-type single-transition-metal layered systems with regards to the active ion and transition metal at hand. This thesis first investigates the nature of vacancy ordering within the O3 host lattice framework, which is currently the most widely synthesized framework for sodium ion intercalating oxides. I generate predicted electrochemical voltage curves for each of the Na-ion intercalating layered TM oxides using a high-throughput framework of density functional theory (DFT) calculations and determine a set of vacancy ordered phases appearing as ground states in all NaxMO₂ systems, and investigate the energy effect of stacking of adjacent layers. I also examine the influence of transition metal mixing and transition metal migration on the materials' thermodynamic properties. Recent work has established the P2 framework as a better electrode candidate structure type than O3, because its slightly larger interlayer spacing allows for faster sodium ion diffusion due to lower diffusion barriers. However, little has been resolved in explaining what stabilizing mechanisms allow for the formation of P-type materials and their synthesis. This work therefore also investigates what stabilizes P2, P3 and O3 materials and what makes them synthesizable at given synthesis conditions, both for the optimization of synthesis techniques and for better-guided material design. It is of further interest to understand why some transition metal oxide systems readily form P2 or P3 compounds while others do not. I investigate several possible stabilizing mechanisms that allow P-type layered sodium metal oxides to by synthesized, and relate these to the choice of transition metal in the metal oxide structure. Finally, this work examines the difficulty of sodium ion intercalation into graphite, which is a commonly used anode material for lithium ion batteries, proposing possible reasons for why graphite does not reversibly intercalate sodium ions and why cointercalation with other compounds is unlikely. This thesis concludes that complex stabilizing mechanisms that go beyond simple electrostatics govern the intercalation of sodium ions into layered systems, giving it advantages and disadvantages over lithium ion batteries and outlining design principles to improve full-cell sodium ion battery materials.
by Alexandra Jeanne Toumar.
Ph. D.
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Li, Xianji. "Metal nitrides as negative electrode materials for sodium-ion batteries." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/374787/.
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Fu, Xuewei. "Graphene-V2O5 Hybrid Aerogels As Electrode Materials For Electrochemical Capacitors." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430499247.
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Renman, Viktor. "Structural and Electrochemical Relations in Electrode Materials for Rechargeable Batteries." Doctoral thesis, Uppsala universitet, Strukturkemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334078.
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Rechargeable batteries have already conquered the market of portable electronics (i.e., mobile phones and laptops) and are set to further enable the large-scale deployment of electric vehicles and hybrid electric vehicles in a not too distant future. In this context, a deeper understanding of the fundamental processes governing the electrochemical behavior of electrode materials for batteries is required for further development of these applications. The aims of the work described in this thesis have been to investigate how electrochemical properties and structural properties of novel electrode materials relate to each other. In this sense, electrochemical characterization, structural analysis using XRD and their combined simultaneous use via in operando XRD experiments have played a crucial part. The investigations showed that: Two oxohalides, Ni3Sb4O6F6 and Mn2Sb3O6Cl, react with Li-ions in a complex manner involving different types of reaction mechanisms at low voltages in Li half cells. In operando XRD show that both of these materials are reduced in a conversion reaction via an in situ formation of nanocomposites, which proceed to react reversibly with Li-ions in a combination of alloying and conversion reactions. Carbon-coated Na2Mn2Si2O7 was synthesized and characterized as a possible positive electrode material for non-aqueous Na-ion batteries. DFT calculations point to a structural origin of the modest electrochemical behavior of this material. It is suggested that structural rearrangements upon desodiation are associated with large overpotentials. It is demonstrated via an in operando synchrotron XRD study that Fe(CN)6 vacancies in copper hexacyanoferrate (CuHCF) play an important role in the electrochemical behavior toward Zn2+ in an aqueous CuHCF/Zn cell. Furthermore, manganese hexacyanomanganate (MnHCM) is shown to react reversibly with Li+, Na+ and K+ in non-aqueous alkali metal half cells. In contrast to CuHCF, which is a zero-strain material, MnHCM undergoes a series of structural transitions (from monoclinic to cubic) during electrochemical cycling.
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Tanaka, Clifford T. (Clifford Takashi). "Ferromagnet-insulator-ferromagnet tunneling with one half-metallic electrode." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40602.
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Lovett, Brendon. "Three molecular materials studied by positive muons and magnetometry." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365360.
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