Switching from fossil-fuel-powered vehicles to electric vehicles has become an international focus in the pursuit of combatting climate change. Regardless, the adoption of electric vehicles has been slow, in part, due to range anxiety. One solution to mitigating range anxiety is to provide a more accurate state of charge (SOC) and range estimation. SOC estimation of lithium-ion batteries for electric vehicle application is a well-researched topic, yet minimal tools and code exist online for researchers and students alike. To that end, a publicly available Kalman filter-based SOC estimation function is presented. The MATLAB function utilizes a second-order resistor-capacitor equivalent circuit model. It requires the SOC-OCV (open circuit voltage) curve, internal resistance, and equivalent circuit model battery parameters. Users can use an extended Kalman filter (EKF) or adaptive extended Kalman filter (AEKF) algorithm and temperature-dependent battery data. A practical example is illustrated using the LA92 driving cycle of a Turnigy battery at multiple temperatures ranging from -10C to 40C. Current range estimation methods suffer from inaccuracy as factors including temperature, wind, driver behaviour, battery voltage, current, SOC, route/terrain, and much more make it difficult to model accurately. One of the most critical factors in range estimation is the battery. However, most models thus far are represented using equivalent circuit models as they are more widely researched. Another limitation is that any machine learning-based range estimation is typically based on historical driving data that require odometer readings for training. A range estimation algorithm using a machine learning-based voltage estimation model is presented. Specifically, the long short-term memory cell in a recurrent neural network is used for the battery model. The model is trained with two datasets, classic and whole, from the experimental data of four Tesla/Panasonic 2170 battery cells. All network training is completed on SHARCNET, a resource provided by Canada Compute to researchers. The classically trained network achieved an average root mean squared error (RMSE) of 44 mV compared to 34 mV achieved by the network trained on the whole dataset. Based on the whole dataset, all test cases achieve an end range estimation of less than 5 km with an average of 0.29 km. / Thesis / Master of Applied Science (MASc)

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Transportsektorn är en av världens största producenter av växthusgas därav är dess avkarbonisering essentiell för att uppnå Parisavtalets mål för CO2-emissioner. Ett viktigt steg för att uppnå dessa mål utförs genom elektrifiering. Litium-jon-batterier (eng. litium-ion batteries, ’LIB’) har blivit väldigt populära energilagringssystem för batteridrivna elektriska fordon (eng. battery electric vehicles, ’BEV’) men tenderar att åldras, precis som alla andra batterier. Därav krävs forskning kring batteriföråldring på grund av nedbrytningsprocessernas inverkan på prissättningen, prestationerna och miljöpåverkan av BEV. Olika modeller används för att beskriva batteriernas åldrande. Datadrivna modeller som förutspår batteriers livstid ökar i popularitet vars noggrannhet och prestationer till stor del beror på indatats kvalitet. Formatet för tidsinhämtade data kräver enorma mängder lagringsutrymme, hög processkapacitet och längre processer; något ’reducerad’ eller ’aggregerad’ data delvis åtgärdar. Denna avhandling fokuserar på att utveckla en metodik för användning av dynamiska fordonsdata i ’aggregerad’ form. Tidsloggade data inhämtade från kallklimatstesting av Scanias BEV-prototyp användes varav interaktionseffekterna mellan diverse fordonsparametrar samt deras effekt på batteriåldring utifrån en batteriåldringsmodell analyserades. Olika tillvägagångssätt för strukturering av dynamiska fordonsdata i modellen undersöktes också. Tolv aggregeringsscenarion designades och testades. Dessutom valdes tre scenarion för uppskattningar och jämförelser av återstående användbar livslängd (eng. remaining-useful-life, ’RUL’) tillsammans med resultat från tidsinhämtade data. Slutligen drogs slutsatser om: parameterinteraktioner, struktur av dynamiska fordonsdata och RUL. Flera framtida utvecklingsområden har också föreslagits bland annat: tester av andra aggregeringstekniker, utöka modellen till tjänstefordon samt kategorisera användningsbeteenden av fordon för att förbättra RUL-uppskattningar. / The transport sector is one of the world’s largest greenhouse gas producing sector and it’s decarbonisation is imperative to achieve the CO2 emission targets set by the Paris Agreement. One important step towards achieving these targets is through electrification of the sector. Lithium-ion batteries (LIBs) have become very popular energy storage systems for battery electric vehicles (BEVs). However, LIBs like all other batteries, tend to age. Hence, the study of the battery ageing phenomena is very essential since the degradation in battery characteristics hugely determines the cost, performance and the environmental impact of BEVs. Different modelling approaches are used to represent battery ageing behaviour. Data-driven models for predicting the lifetime of batteries are becoming popular. However, the accuracy and performance of data-driven models largely depends upon the quality of data being used as the input. Time-sampled format of logging data results in huge data files requiring enormous amounts of storage space, high processing power requirements and longer processing times. Instead, using data in a ’reduced’ or ‘aggregated’ form can help in addressing these issues. This thesis work focuses on developing a methodology for using dynamic vehicle data in an ‘aggregated’ form. Time-sampled data from a Scania prototype BEV truck, recorded during cold climate test, was used. The interaction effects between various vehicle parameters and their effect on battery ageing in a battery ageing model were analyzed. Different approaches to structuring dynamic vehicle data for use in the model were also studied. Twelve aggregation scenarios were designed and tested. Furthermore, three scenarios were selected for making remaining-useful-life (RUL) estimations and compared alongside time-sampled data results. Finally, conclusions about parameter interactions, structuring of dynamic vehicle data and RUL estimations were drawn. Several next steps for future work have also been suggested such as testing other aggregation techniques, extending the model to vehicle fleets and categorizing vehicle usage behaviours to make better RUL estimations.

The Swedish Armed Forces are investigating high-risk applications where lithium-ion batteries (LIB) can replace traditional lead-acid batteries. Understanding the potential safety risks and evaluating a battery's instability is crucial for military applications. This report aimed to identify critical safety parameters (temperature, potential, and impedance) in commercial batteries with NMC and LFP electrode chemistries, and to investigate how surrounding cells are affected when a battery suffers from thermal runaway (TR) in a battery module developed by FOI. Accelerated rate calorimetry (ARC) experiments on NMC-based Samsung SDI INR21700-40T and INR21700-50E and LFP-based A123 Systems ANR26650m1-B batteries were conducted to identify critical onset conditions of TR. ARC experiments were conducted with continuous electrochemical impedance spectroscopy (EIS) measurements to correlate thermal behavior with electrochemical changes in the cell impedance and voltage. The NMC-based batteries showed a distinct endothermic reaction between 116 °C and 121 °C, an onset temperature of exothermic self-heating at around 120 °C, which progressed to an explosive decomposition at about 170 °C and resulted in an adiabatic temperature rise of 250 °C to 290 °C. A significant increase in the cell’s impedance at around 100 °C indicated that the current interrupt device (CID) was triggered due to gas formation and critical pressure build-up within the cell. The LFP-based battery demonstrated improved thermal stability during ARC measurements and did not suffer from TR when heated to 300 °C. Thermal runaway propagation experiments were conducted in a battery module developed by FOI. The identified onset temperatures and electrochemical markers were then used to evaluate the stability of the module cells. Cell temperature increases between 16 °C and 48 °C was observed in cells directly adjacent to the trigger cell. Cells further from the trigger cell experienced uniform temperature increases of between 8 °C and 30 °C. EIS measurements of the module cells revealed no significant changes in their impedance spectra. The insulating polymer wrap around each cell was found to be crucial in preventing TR propagation. TR propagated from cell-to-cell in the module when the insulating wraps were removed, and cells were in direct contact with the thermally conductive heat sink. / Försvarsmakten undersöker högriskapplikationer där litiumjonbatterier kan ersätta traditionella blysyrabatterier. Att förstå säkerhetsrisker och utvärdera ett batteris instabilitet är särskilt viktigt för militära tillämpningar. Denna rapport syftar till att identifiera kritiska säkerhetsparametrar (temperatur, spänning och impedans) för kommersiella batterier med NMC- och LFP-elektrodkemier samt undersöka hur omkringliggande celler påverkas när ett batteri termiskt rusar (TR) i en batterimodul utvecklad av FOI. ARC-experiment genomfördes på NMC-baserad Samsung SDI INR21700-40T och INR21700-50E och A123 Systems ANR26650m1-B batterier för att karakterisera förloppet av termisk rusning (TR). ARC-experiment utfördes med kontinuerliga elektrokemisk impedansspektroskopi (EIS) för att korrelera termiskt beteende med elektrokemiska förändringar i cellimpedansen och spänningen. Det NMC-baserade batterierna uppvisade en tydlig endotermisk reaktion mellan 116 °C och 121 °C, exotermiska reaktioner påbörjades vid 120 °C och ledde till explosiv termisk rusning vid cirka 170 °C, vilket gav upphov till en adiabatisk temperaturökning på 250 °C till 290 °C. En signifikant ökning av cellens impedans vid cirka 100 °C indikerade att den inre säkerhetsventilen utlöstes på grund av gasbildning och kritisk tryckuppbyggnad i cellen. Det LFP-baserade batteriet visade förbättrad termisk stabilitet under ARC-mätningar och drabbades inte av TR vid uppvärmning till 300 °C. Termiska rusningsförsök genomfördes på en batterimodul utvecklad av FOI. De identifierade starttemperaturerna och elektrokemiska markörerna användes för att utvärdera modulcellernas stabilitet. Celltemperaturökningar mellan 16 °C och 48 °C observerades i celler direkt intill triggcellen. Celler längre från triggcellen upplevde likformiga temperaturökningar mellan 8 °C och 30 °C. EIS-mätningar av modulcellerna avslöjade inga signifikanta förändringar i deras impedansspektra. Det isolerande polymeromslaget runt varje cell var avgörande för att förhindra propagering av termisk rusning i modulen. Termisk rusning propagerade från cell till cell i modulen när de isolerande omslagen togs bort och cellerna var i direkt kontakt med den värmeledande kylflänsen.

Litiumjonbatterier (LIB) är viktiga komponenter i dagens teknologi och används för att driva en mängd olika elektroniska system, allt från datorer och mobiltelefoner till bilar och flygplan. Eftersom efterfrågan på effektiv energilagring fortsätter att växa finns ett fortsatt behov för forskning och utveckling inom området. Denna rapport undersöker hårt kol, ett lovande material för anoder i litiumjonbatterier och andra alkali-jon batterier. I likhet med grafit är hårt kol ett kolbaserat material som inte är en väldefinierad allotropp utan en komplex blandning med avseende på både hybridiseringstillstånd och långdistansordning.  Därför är den mycket dåligt definierat. Ändå är hårt kol ett önskvärt material eftersom det kan produceras från förnybara resurser samt på grund av dess kompatibilitet med natrium, vilket möjliggör natriumjonbatterier. I den här studien har elektroder av hårt kol syntetiserats och litierats i olika grader och sedan studerats med 7Li NMR-spektroskopi där både spektra och longitudinella relaxationshastigheter mättes. Vid lägre litieringsnivåer observerades tydliga smala 7Li toppar inom intervallet 4-16 ppm, vilket indikerar förekomsten av joniskt litium. Vid högre litieringsnivåer framträdde en bred topp vid 61 ppm. Utseendet av denna topp, tillsammans med en hög Knight-skift, indikerar närvaron av kvasi-metalliskt litium. Det är värt att notera att detta kvasi-metalliska litium finns i de oordnade och porösa områdena hos hård kol. 7Li longitudinella relaxationshastigheter, som rapporterar om jonisk dynamik, registrerades vid olika temperaturer och från det observerade temperaturberoendet beräknades den genomsnittliga aktiveringsenergin för de involverade joniska rörelserna. Intressant nog visade sig denna aktiveringsenergi vara lägre jämfört med den i PAN-baserade kolfibrer och grafit, som båda uppvisar en högre grad av ordning. Denna observation tyder på ett samband mellan lokal oordning och snabbare jondynamik. / Lithium-ion batteries (LIB) are vital components of modern technology, powering a wide range of devices from computers and cell phones to cars and aeroplanes. As the demand for efficient energy storage continues to grow, research and development in the field of lithium-ion batteries remain active. This report focuses on the investigation of hard carbon, a promising anode material for lithium-ion batteries and other alkali-ion batteries. Akin to graphite, hard carbon is a carbon-based material that is not a well-defined allotrope but a complex mixture with regard to both hybridization state and long-range order. Hence it is very poorly defined. Yet, hard carbon is a desirable material as it can be produced from renewable resources and because of its compatibility with sodium, allowing for sodium-ion batteries. In this study, hard carbon electrodes were synthesised and lithiated to various degrees and then studied with 7Li NMR spectroscopy where both spectra and longitudinal relaxation rates were measured.   At lower lithiation levels, distinct narrow 7Li peaks were observed within the 4-16 ppm range, indicating the presence of ionic lithium. At higher lithiation levels a broad peak at 61 ppm emerged. The appearance of this peak, along with a high Knight shift, signifies the presence of quasi-metallic lithium, presumably in the more disordered and more porous regions of hard carbon. The 7Li longitudinal relaxation rates, reporting on ionic dynamics, were recorded at different temperature and from the observed temperature dependence the average activation energy for the involved ionic motions was calculated. Interestingly, this activation energy was found to be lower compared to that for PAN-based carbon fibres and graphite, both of which exhibit a higher degree of order. This observation suggests a correlation between local disorder and faster ion dynamics.

Nous avons mis au point une approche novatrice pour la synthèse d’un matériau de cathode pour les piles lithium-ion basée sur la décomposition thermique de l’urée. Les hydroxydes de métal mixte (NixMnxCo(1-2x)(OH)2) ont été préparés (x = 0.00 à 0.50) et subséquemment utilisés comme précurseurs à la préparation de l’oxyde de métal mixte (LiNixMnxCo(1-2x)O2). Ces matériaux, ainsi que le phosphate de fer lithié (LiFePO4), sont pressentis comme matériaux de cathode commerciaux pour la prochaine génération de piles lithium-ion. Nous avons également développé un nouveau traitement post-synthèse afin d’améliorer la morphologie des hydroxydes. L’originalité de l’approche basée sur la décomposition thermique de l’urée réside dans l’utilisation inédite des hydroxydes comme précurseurs à la préparation d’oxydes de lithium mixtes par l’intermédiaire d’une technique de précipitation uniforme. De plus, nous proposons de nouvelles techniques de traitement s’adressant aux méthodes de synthèses traditionnelles. Les résultats obtenus par ces deux méthodes sont résumés dans deux articles soumis à des revues scientifiques. Tous les matériaux produits lors de cette recherche ont été analysés par diffraction des rayons X (DRX), microscope électronique à balayage (MEB), analyse thermique gravimétrique (ATG) et ont été caractérisés électrochimiquement. La performance électrochimique (nombre de cycles vs capacité) des matériaux de cathode a été conduite en mode galvanostatique. / We have developed a novel approach to the synthesis of cathode materials for lithium-ion batteries, based on the thermal decomposition of urea. Mixed metal hydroxides (NixMnxCo(1-2x)(OH)2), x = 0.00 to 0.50, were prepared and subsequently used as precursor for lithiated mixed metal oxide (LiNixMnxCo(1-2x)O2). These materials along with lithium iron phosphate (LiFePO4) are being considered as cathode materials for the next generation of lithium-ion batteries. We have also developed new post-synthetic treatments on the hydroxides in order to enhance the morphology, which would result in improved electrode properties. The novelty of this thesis is that for the first time mixed metal hydroxides for use as precursors for lithium mixed oxides have been prepared via a uniform precipitation technique from solution. In addition, we have proposed new treatments techniques towards the more traditional synthesis method for mixed metal hydroxides. The results obtained from these two methods are summarized within two articles that were recently submitted to peer-reviewed journals. Within this thesis, all materials were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and electrochemical measurements. The electrochemical performance (capacity vs cycle number) of the cathode materials were tested galvanostatically.

In this thesis, a simulation model developed in MATLAB® in consideration of system losses based on lithium ion-battery is presented. The purpose of the simulation model is to investigate peak shaving potential in the residential distribution network. In other word to determine an optimal threshold limit and battery capacity depending on if the battery system is placed at the transformer or household level. In the report there were economic calculations executed showing that profitability of investing in a battery system depends on the threshold limit and battery capacity. / I denna rapport presenteras analys av toppeffektreducering med ett simuleringsprogram baserad på litium-jon batteri med hänsyn till systemförlust. Simuleringsmodellen är uppbyggd i MATLAB® där metoder som Coulomb counting implementerades. Syftet med simuleringsprogrammet är att definiera en optimal tröskelgräns samt batterikapacitet på transformator- och hushållsnivån. I rapporten utfördes ekonomiska beräkningar som tyder på att lönsamheten för investering av ett batterisystem beror på tröskelgräns och batterikapacitet.

Le polymère poreux (PM) associe les avantages double des matériaux poreux et des polymères, ayant la structure unique de pore, la porosité supérieure et la densité inférieure, ce qui possède une valeur d’application importante dans les domaines de l'adsorption, le soutien de catalyseur, le séparateur de batterie, la filtration, etc. Actuellement, il existe plusieurs façons de préparer le PM, comme la méthode de gabarit, la méthode de séparation de phase, la méthode d'imagerie respiratoire, etc. Chacune des méthodes ci-dessus existe ses propres avantages, mais la préparation à grande échelle de PM à structure de pore contrôlable et aux fonctions spécifiques est toujours un objectif à long terme sur le domaine et l'un des principaux objectifs de ce mémoire. La co-extrusion de microcouche est une méthode pour produire de façon efficace et successive des polymères avec des structures de couches alternées, ayant les avantages de haute efficacité et faible coût. Par conséquent, sur les exigences structurelles de PM de l’application spécifique, ce mémoire a conçu le PM avec une structure spécifique et une co-extrusion de microcouche de manière créative combinée avec la méthode traditionnelle de préparation de PM (méthode de gabarit, méthode de séparation de phase), en combinant les avantages des deux méthodes, les PM avec une structure de pore idéale peuvent être préparés en grande quantité et l’on peut également explorer son application dans les séparateurs de batteries au lithium-ion et l'adsorption d'hydrocarbures aromatiques polycycliques.Le plus important, dans la deuxième partie de cet essai, se trouve que la simulation micro-numérique est utilisée pour étudier le transport et le dépôt de particules dans des milieux poreux pour explorer le mécanisme des matériaux poreux dans les domaines de l'adsorption et du séparateur de batterie. Le code de 3D-PTPO (un modèle tridimensionnel de suivi des particules combinant Python® et OpenFOAM®) est utilisé pour étudier le transport et le dépôt de particules colloïdales dans des milieux poreux, l’on adopte trois modèles (colonne, venturi et tube conique) pour représenter différentes formes de matériaux poreux. Les particules sont considérées comme des points matériaux pendant le transport, le volume des particules sera reconstitué et déposé comme partie de la surface du matériau poreux pendant le dépôt, la caractéristique principale de ce code est de considérer l'influence du volume des particules déposées sur la structure des pores, les lignes d'écoulement et le processus du dépôt des autres particules. Les simulations numériques sont d'abord conduites dans des capillaires simples, le travail de chercheurs de Lopez et d’autres est réexaminé en établissant un modèle géométrique tridimensionnel plus réaliste et il explore les mécanismes cachés derrière les règles de transmission et de dépôt. Par la suite, des simulations numériques sont effectuées dans des capillaires convergents-divergents pour étudier la structure des pores et l'effet de nombre Peclet sur le dépôt de particules. Enfin, l’on étudie l’effet double de l'hétérogénéité de surface et de l'hydrodynamique sur le comportement de dépôt de particules. / Due to the combination of the advantages of porous media and polymer materials, polymeric porous media possess the properties of controllable porous structure, easily modifiable surface properties, good chemical stability, etc., which make them applicable in a wide range of industrial fields, including adsorption, battery separator, catalyst carrier, filter, energy storage, etc. Although there exist various preparation methods, such as template technique, emulsion method, phase separation method, foaming process, electrospinning, top-down lithographic techniques, breath figure method, etc., the large-scale preparation of polymeric porous media with controllable pore structures and specified functions is still a long-term goal in this field, which is one of the core objectives of this thesis. Therefore, in the first part of the thesis, polymeric porous media are firstly designed based on the specific application requirements. Then the designed polymeric porous media are prepared by the combination of multilayer coextrusion and traditional preparation methods (template technique, phase separation method). This combined preparation method has integrated the advantages of the multilayer coextrusion (continuous process, economic pathway for large-scale fabrication, flexibility of the polymer species, and tunable layer structures) and the template/phase separation method (simple preparation process and tunable pore structure). Afterwards, the applications of the polymeric porous media in polycyclic aromatic hydrocarbons adsorption and lithium-ion battery separator have been investigated.More importantly, in the second part of the thesis, numerical simulations of particle transport and deposition in porous media are carried out to explore the mechanisms that form the theoretical basis for the above applications (adsorption, separation, etc.). Transport and deposition of colloidal particles in porous media are of vital important in other applications such as aquifer remediation, fouling of surfaces, and therapeutic drug delivery. Therefore, it is quite worthy to have a thorough understanding of these processes as well as the dominant mechanisms involved. In this part, the microscale simulations of colloidal particle transport and deposition in porous media are achieved by a novel colloidal particle tracking model, called 3D-PTPO (Three-Dimensional Particle Tracking model by Python® and OpenFOAM®) code. The particles are considered as a mass point during transport in the flow and their volume is reconstructed when they are deposited. The main feature of the code is to take into account the modification of the pore structure and thus the flow streamlines due to deposit. Numerical simulations were firstly carried out in a capillary tube considered as an element of an idealized porous medium composed of capillaries of circular cross sections to revisit the work of Lopez and co-authors by considering a more realistic 3D geometry and also to get the most relevant quantities by capturing the physics underlying the process. Then microscale simulation is approached by representing the elementary pore structure as a capillary tube with converging/diverging geometries (tapered pipe and venturi tube) to explore the influence of the pore geometry and the particle Péclet number (Pe) on particle deposition. Finally, the coupled effects of surface chemical heterogeneity and hydrodynamics on particle deposition in porous media were investigated in a three-dimensional capillary with periodically repeating chemically heterogeneous surfaces.

In dieser Arbeit untersuchen wir zwei Modelle, die das Laden und Entladen einer Lithium-Ionen Batterie beschreiben. Beide Modelle spiegeln eine Hysterese in dem Spannungs-Ladungs-Verlauf wider. Wir skizzieren den Modellierungsprozess von einem diskreten vielteilchen Modell sowie einem kontinuierlichen vielteilchen Modell. Das erste führt zu einer axiomatischen Beschreibung der Evolution makroskopischer Größen, während das zweite in eine nichtlineare Fokker-Planck Gleichung mündet. Wir zeigen die Existenz und Eindeutigkeit von Lösungen der nichtlinearen Fokker-Planck Gleichung und untersuchen deren qualitative Eigenschaften. Wir benutzen Interpolationsräume und Halbgruppen sektorieller Operatoren um den semilinearen Charakter der partiellen Differentialgleichung auszunutzen. Um globale Existenz zu erhalten, schätzen wir die Dissipation einer mit dem Modell verknüpften Energie ab. Diese Energie ist verwandt mit der L-log-L Norm, welche wir mithilfe einer Gagliardo-Nirenberg Ungleichung zu der L^2 Norm in Verbindung setzen können. Die notwendigen und hinreichenden Bedingungen zur globalen Existenz von Lösungen sind aus physikalischer Sicht plausibel. Der Ladezustand der Batterie muss innerhalb der Werte Voll und Leer sein. In numerischen Experimenten untersuchen wir das qualitative Verhalten von Lösungen. Wir zeigen die Konvergenz der numerischen Lösungen zu den exakten Lösungen. Dafür nutzen wir ähnliche Techniken wie bei der lokalen Existenztheorie. Wir beobachten die Tendenz von Lösungen sich um bestimmte Punkte zu konzentrieren. Unterstützt durch die formale Asymptotik zeigt dies für eine bestimmte Wahl von Parameter-Skalierungen, dass Lösungen gegen Dirac-Maße konvergieren. In diesem Grenzverhalten wird das System durch die Evolution von makroskopischen Größen beschrieben, welche wir auch in dem diskreten vielteilchen Modell wiederfinden. In diesen makroskopischen Größen lässt sich eine Hysterese beobachten. / We discuss two models which describe the charging and discharging of a lithium-ion battery and especially the hysteretical behaviour therein. We give an overview on the modelling process for a discrete many particle model and a continuous many particle model. The former results in an axiomatic description of macroscopic quantities while the latter gives a nonlinear Fokker-Planck equation. The nonlinear Fokker-Planck equation is analysed with respect to existence and uniqueness of solutions as well as qualitative behaviour of solutions. The nonlinearity in this partial differential equation stems from a coefficient which depends on the solution first non-local and second in a higher order. We use interpolation spaces and semigroups generated from sectorial operators to show the existence and uniqueness of solutions locally in time. The global existence in time relies on estimates for the dissipation of an energy. The suitable energy is related to the L-log-L norm and so a Gagliardo-Nirenberg inequality is needed to connect this back to L^2 estimates. It turns out that the conditions for global in time existence of solutions are physical reasonable. One needs that the loading state of the battery shall stay between totally empty and totally full. In numerical experiments we investigate the qualitative behaviour of solutions to the nonlinear Fokker-Planck equation. We are able to show convergence of the numerical solutions to the exact solution. We observe that solutions tend to concentrate at certain points. Supported by results from formal asymptotic expansions, we document the limiting behaviour in a certain scaling of the appearing parameters, which is the formation of Dirac measures. The evolution of the global quantities, which we observe in numerical simulations, is the same as what results from the discrete many particle model and one observes hysteretic behaviour in macroscopic quantities.

Le fonctionnement des batteries lithium-ion, qu’il soit normal ou dans des conditions abusives, est accompagné d’une génération de gaz en particulier lors des premiers cycles. Celle-ci est intrinsèque au dispositif et est soumise à de nombreux paramètres tels que les matériaux d’électrodes utilisés, l’électrolyte ou encore les conditions opératoires. Cette génération de gaz est délétère : elle conduit à l’augmentation de la pression interne des batteries et pose donc des problèmes de sécurité. Cette étude vise à quantifier les volumes de gaz générés et à comprendre les mécanismes liés à la surpression dans les batteries. A cet effet, le format de batterie « pouch cell » a été adopté tout au long de ce travail de thèse. L’électrolyte choisi est le mélange EC:PC:3DMC + 1 mol.L-1 LiPF6. La première partie de ce travail est dédiée à la mise au point d’un protocole expérimental basé sur (i) l’analyse des matériaux d’électrodes (NMC, LFP, Gr, et LTO), (ii) la solubilité de gaz (O2, H2) comparées à (CO2, CH4) par PVT, et (iii) la quantification des volumes de gaz générés durant le cyclage en pouch cell, corrélée aux performances électrochimiques. Une analyse préalable en demi-piles et en dispositifs complets Gr//NMC et LTO//LFP a également été réalisée afin d’anticiper les performances attendues en pouch cells. Une analyse critique des données (de la littérature et de nos mesures) a permis de définir une procédure optimisée pour obtenir des résultats reproductibles et comparables lors des mesures de volume en pouch cells. La seconde partie de cette thèse consiste en la quantification du volume de gaz produit au cours du cyclage des pouch cells Gr//NMC, Gr//LFP, LTO//LFP et LTO//NMC. Ainsi, les tensions de fin de charge, l’effet du sel et de la température ont été discutés pour dégager les paramètres déterminants dans la génération de gaz en particulier lors de la formation de la SEI. Enfin, une analyse de la composition du gaz récupéré a été effectué par GC-MS et FTIR. A partir de résultats obtenus, des mécanismes ont été proposés et discutés. / The functioning of lithium-ion batteries, may it be under normal use or under abusive conditions, is accompanied by gas generation, especially during the first cycles. This extent of gas generation is dependent on the choice of electrode materials, the electrolyte, and the operating conditions. This gas generation is detrimental: the build-up of pressure leads to the over-pressure in the battery, raising serious concerns. This study is aimed at understanding the fundamental mechanisms governing these reactions. To do so, the « pouch cell » configuration was adopted throughout this thesis. The electrolyte we worked on is the mixture EC:PC:3DMC + 1 mol.L-1 LiPF6. The first chapter of this work is dedicated to development of an experimental protocol based on (i) the analysis of the electrodes materials (NMC, LFP, Gr and LTO), (ii) the gas solubilities (O2, H2) compared to (CO2, CH4) by PVT method, and (iii) the quantification of the volume of generated gases during the cycling of pouch cells which was correlated to the electrochemical performances. A preliminary analysis of half-cells and full cells Gr//NMC and LTO//LFP were also conducted to foresee the performances of the pouch cells. A critical analysis of data taken from the literature and from our own experiments enabled the optimization of a proper procedure to get reproducible and comparable results. The second part of this thesis consists in the quantification of the volume of gases generated during the cycling of Gr//NMC, Gr//LFP, LTO//LFP and LTO//NMC pouch cells. In that respect, the voltages of the end of charge and the effect of salt and of temperature were discussed to figure out the essential parameters in the gas generation and in particular during the formation of SEI. Lastly, a compositional analysis of gases was performed using GC-MS and FTIR. Based on those results, a mechanism is proposed and discussed herein.