Målet med projektet var att undersöka samt implementera en fysikbaserad DFN modell för att simulera kalender samt cyklingåldrande av litiumbatterier som används i elbilar. Den fysikbaserade modellen var konstruerad baserad på ett Python biblioteket vid namn PyBaMM, vilket till skillnad från datadrivna modeller ger essentiell information om de kemiska processerna inuti batteriet. Den första delen av projektet täcker konceptet av kalenderåldring, vilket inkluderar en jämförelse mellan tre olika tre olika hastighetsbegränsande SEI modeller. Parametrar som påverkar det erhållna resultatet från modellen är identifierade, estimerade, och till slut validerade för att säkerhetsställa att modellen och parametrarna är identifierbara gentemot experimentella data. Resultatet av jämförelsen gav att SEI tillväxt begränsad av litium interstitiell diffusion är den mest optimala modellen att applicera när kalenderåldring för litiumbatterier ska modelleras. Resultaten visade också att endast en parameter, inre SEI litium interstitiell diffusivitet ska justeras för att erhålla optimal anpassning mot experimentella data. Andra delen av projektet använde resultatet från den första delen och litium plätering implementerades som en andraåldringsmekanism som undersöktes under tre olika laddningsprotokoll. Modellen var optimerad och anpassad gentemot experimentella data, där parametervärdet för kinetisk hasighetskonstanten för plätering var estimerad. Den optimerade modellen användes därefter för att erhålla mer information om elektrokemiska variabler för att kunna analysera samt beskrivaåldringsprocessen utan att behöva genomföra praktiska laborationer. Resultaten visade att mängden pläterat litium på den negativa elektroden ökade för celler som var exponerade till högre ström under laddningsprocessen, samt när cellerna var laddade vid höga SoC nivåer. Sammanfattningsvis, visade modellen hög potential att representera och evaluera experimentella data, samt tillhandahålla en inblick i elektrokemiska processer och kapacitetsförluster länkade till SEI tillväxt och litium plätering. Däremot, för att erhålla en högre grad noggrannhet av elektrokemiskaåldringsmekanismer i litiumbatterier, fler ytterligare mekanismer måste implementeras såsom mekanisk stress av både negativ och positiv elektrod. / The aim of this study was to investigate and apply a physics-based DFN model to simulate the calendar and cycling ageing of lithium-ion batteries manufactured for EV applications. The physics-based cell ageing model was constructed based on the open-source software Python library PyBaMM, which in comparison to data-driven models provides more essential information about the chemical process within the battery cell. The first part of the project covers the concept of calendar ageing which includes comparisons between three different rate-limiting SEI growth models. Parameters that affect the output from the physics-based model are isolated, estimated with numerical methods, and lastly validated to ensure that the model and the parameters rep- resent the physics behind the experimental data. It was found that the SEI growth limited by lithium interstitial diffusion is the most optimal model to apply for a physics-based model when modeling calendar ageing. It was also found that the only parameter that should be tuned against experimental data is the inner SEI lithium interstitial diffusivity. The second part of the project utilizes the results from the first part and introduces lithium plating as a second cell ageing mechanism under three different charging protocols. The model was optimized and fitted against experimental data by sweeping the lithium plating kinetic rate constant parameter. The optimized model was thereafter used to generate outputs that more thoroughly can explain the degradation effects of the cell without constructing real-world experiments. Where increased rate of plated lithium could be observed for the cell subjected to higher charging C-rate, and when the cells were charged at high SoC levels. To summarize, the model showed great potential in representing and evaluating the experimental data and providing the project with insight into the electrochemical processes and cell capacity losses of SEI growth and lithium plating. However, in order to achieve a higher accuracy of cell ageing model in relation to the lithium-ion cells used in customer vehicles, several additional cell degradation mechanisms have to be introduced, such as mechanical degradation of the two electrodes.

Strukturella batterier är multifunktionella; de tillhandahåller lagring av elektrokemisk energi samtidigt som de bidrar med en lastbärande funktion. Tillsammans möjliggör detta att batteriet kan integreras i karossen hos ett elektriskt fordon eller apparat. Denna multifunktionalitet möjliggör således en avsevärd reducering i fordonets vikt. Kompositmaterialet är förstärkt av kolfiberelektroder, innesluten i en elektrolytstruktur. För att förverkliga detta koncept måste batteriets elektrolyt kunna motstå mekanisk belastning, samtidigt som den transporterar joner mellan batteriets elektroder. Denna studie syftar till att bygga vidare på konceptet av fas-separerade polymerelektrolyter, skapade från polymerisationsinducerad fasseparation via termisk härdning, vilket är en teknik utvecklad av Schneider et al. och Ihrner et al. Vidare undersöks effekten av att dels använda en elektrolytlösning baserad på EC:PC, men även att inkorporera tioler till polymernätverket. Tvärbindningsmolekylerna som användes i denna studie inkluderade trimetylolpropan tris(3-merkaptopropionat) (3TMP), pentaerythritol tetrakis(3-merkaptopropionat) (4PER), och dipentaerythritol hexakis-(3-merkaptopropionat) (6DPER). Dessa skiljer sig i antal funktionella tiolgrupper. Konduktivitet, termo-mekanisk prestanda och strukturberoende egenskaper undersöktes genom tre laborativa faser. Den första fasen behandlade inverkan på elektrolytsystemet av ändrat lösningsmedel, tiol-funktionalitet samt tiolgruppförhållandet gentemot allyl gruppen på den primära monomeren. Sampolymeren innehållandes 6DPER uppvisade bäst multifunktionalitet, varpå denna utvecklades vidare i fas två där en optimal sammansättning fastställdes som bestod utav 45 viktprocent jonlösning. I den slutliga fasen konstruerades en halv-cell baserat på den tidigare optimerade elektrolytkompositionen; den uppmätta kapaciteten visar tydlig förbättring jämfört med tidigare forskning. Resultatet som erhölls i denna studie bidrar till förståendet av strukturella batteri-elektrolyter samt den forskning som en dag kan komma att förverkliga strukturella batterier och dess tillämpningskrav. / Structural batteries are multifunctional; providing electrochemical energy storage synergistically with a load-bearing function that enables their integration into the body panels of electric devices and vehicles. Thus, massless energy can be achieved. As a composite material, it is composed of reinforcing carbon fibre electrodes embedded in an electrolyte matrix. To realize this concept, the electrolyte must simultaneously transfer mechanical load and transport ions between electrodes. The following study builds on a phase-separated polymer electrolyte, created using polymerization-induced phase separation via thermal curing, formulated by Schneider et al. and Ihrner et al.. The impact of the incorporation of thiols for copolymerization and as cross-linking agents for the polymer network was researched along with use of an EC:PC-based solvent. The three thiols studied were: trimethylolpropane tris(3-mercaptopropionate) (3TMP), pentaerythritol tetrakis(3-mercaptopropionate) (4PER), and dipentaerythritol hexakis-(3-mercaptopropionate) (6DPER). These differed in regard to the amount of thiol functional groups present. Ionic conductivity, thermo-mechanical performance and structure-property relationships were studied across 3 laboratory phases. The first phase concerned the effect of thiol-functionality, the thiol functional group ratio relative to the allyl group present in the primary monomer, and the solvent interaction. 6DPER was concluded to be the most promising cross-linking agent. During the second phase, the effect of electrolyte content was evaluated with an optimum of 45 weight% determined. The third phase concluded the study, wherein a half-cell was assembled with the optimized electrolyte formulation showing improved capacity relative to previous studies. The results developed here contribute to the understanding of structural battery electrolyte systems and their continued research to meet application demands.

Environmental concerns, resource depletion, energy security, technological advancements, and global policies are just a few of the variables influencing the global energy perspective. In the case of technological advancement, lithium batteries play a key role in the development of a more sustainable energy infrastructure. The high energy density and long lifespan of lithium batteries make them ideal for usage in a broad range of applications, such as portable electronics, electric vehicles, and grid-scale energy storage for renewable energy sources. However, there are certain possible concerns regarding the safe operation and performance of lithium batteries, most of which are associated with the temperature sensitivity of lithium batteries. Hence, battery thermal management systems are an essential component of a battery package for regulating the temperature level in lithium batteries to avoid the aging process, poor performance, and safety issues.   Many studies have been conducted to develop battery thermal management systems with improved cooling performance. Within this framework, Paper A in this licentiate thesis considers how the design of a lithium battery cell may be improved to reduce the thermal load on the thermal management system. An analytical model based on the integral transform technique is developed to accurately and efficiently predict the thermal behavior of a cylindrical lithium battery cell. Following model validation, the thermal behavior of cylindrical lithium-ion battery cells with different jelly-roll layers and can sizes are compared. The results demonstrate that 21700 cylindrical battery cells outperform other types of cylindrical battery cells in terms of thermal performance. Furthermore, the thermally optimal thicknesses for positive active material, negative active material, positive current collector, and negative current collector are 180, 34, 21, and 20 um, respectively. After learning about design considerations to reduce thermal issues in lithium-ion battery cells and developing a proper tool for further studies, the focus was set on the flow behavior surrounding a cylindrical battery cell in an air-based cooling system. The cooling system under consideration is a wall-bounded cross-flow heat exchanger, the most common air-based cooling system for battery applications. Despite the importance of the cooling system in battery safety, few studies have been conducted to investigate the thermo-flow characteristics of wall-bounded cross-flow heat exchangers. Hence, in the battery research field, it is common to estimate the performance of wall-bounded cross-flow heat exchangers using the thermal characteristics of free cross-flow heat exchangers due to their geometrical similarities. In Paper B, this assumption is scrutinized by comparing the thermo-fluid characteristics of free and wall-bounded cross-flow heat exchangers. According to the results, flow through both heat exchangers shows almost similar thermo-fluid behavior in areas sufficiently far from the bounding walls. A turbulence model study suggests that the k-kl-omega transition model is a time-efficient and reliable turbulence model for capturing thermo-fluid characteristics in such heat exchangers. Moreover, it is observed that the two different heat exchangers have an almost identical area-averaged heat transfer rate despite the local changes in Nusselt number along the height of cells. This finding shows that it is possible to do two-dimensional simulations for applications that only require an area-averaged heat transfer rate on the battery cells. The findings in Paper A and Paper B may be used to investigate the cooling performance of a battery thermal management system with a practical design. Hence, in Paper C, a comprehensive yet simplified model is developed that can be used to study the thermal field of lithium battery cells in a large-scale air-based battery thermal management system. The model consists of the CFD model derived in Paper B, which predicts the flow behavior around cells in the inner region of the battery package, and the analytical model described in Paper A, which determines the thermal field within the battery cells. The area-averaged heat transfer coefficient interconnects the models, and a system of equations is employed to estimate the row-to-row variation of the thermal field. The model is employed to assess the effect of transverse and longitudinal pitch ratios on the thermal performance of an air-based battery thermal management system used in a hybrid electric vehicle.

No description available.

Energy storage systems with many Lithium Ion battery cells per string require sophisticated balancing hardware due to individual cells having manufacturing inconsistencies, different self discharge rates, internal resistances and temperature variations. For capacity maximization, safe operation, and extended lifetime, battery balancing is required. Redistributive Non-Dissipative balancing further improves the pack capacity and efficiency over a Dissipative approach where energy is wasted as heat across shunt resistors. Redistribution techniques dynamically shuttle charge to and from weak cells during operation such that all of the stored energy in the stack is utilized. This thesis identifies and develops different balancing control methods. These methods include a unconstrained optimization problem using a Linear Quadratic Regulator (LQR) and a constrained optimization problem using Model Predictive Control (MPC). These methods are benchmarked against traditional rule based (RB) balancing. The control systems are developed using MATLAB/Simulink and validated experimentally on a multiple transformer individual cell to stack topology. The implementation uses a DC2100A Demo-board from Linear Technology with bi-directional flyback converters to transfer the energy between the cells. The results of this thesis show that the MPC control method has the highest balancing efficiency and minimum balancing time. / Thesis / Master of Applied Science (MASc)

The electric vehicle segments of companies have broadened, and their sales have increased in the past decade. The electric motorcycle sector is growing fast, with improved technology on electric powertrains, increased ranges, charging speeds, and infrastructure. Parallel to the increased sales, the electric battery sector is advancing rapidly, thereby lowering the environmental impacts of these vehicles. The competitive adventure sports sector also benefits from using electric powertrains with their incredible power-to-weight ratio and instant torque. The benefits of using electric vehicles over conventional ones can be seen during the use phase, with zero tailpipe emissions and clean, silent riding.   However, with the expansion of the electric motorcycle sector rolling out new technologies and models, there are uncertainties about whether the overall lifecycle has reduced impacts on the environment. Finding and improving the most sustainable model(s) or solution(s) implies scrutinizing the effects of these motorcycles on the environment, which is the goal of CAKE 0 Emission AB, a Swedish lightweight electric motorbike manufacturer.   The current project will assess the potential environmental impacts of Kalk&, an off-road electric motorcycle model certified for on-road use, designed, and manufactured by CAKE 0 Emission AB. For this purpose, Attributional Life Cycle Assessment was chosen as the method to study the impact of one whole motorbike over a lifetime of 500 battery charging cycles, used by a hypothetical example user in Stockholm, Sweden. The potential environmental impacts are focused on 12 categories using the ReCiPe Midpoint (H) method.   As expected from an electric vehicle, the results show that the impacts mainly stem from the manufacturing phase of the motorbike. The hotspots in the manufacturing phase arise from producing the battery, the electric motor, and the electrical components like lights, the charger, and cables. The materials used for construction that have a high share of impact are Copper and Aluminium. Another environmental hotspot is the casting manufacturing process. Within the vehicle use phase, the impact of using solar energy in Sweden for charging the batteries is not immediately intuitive and has shown to be higher than the Swedish electricity board mix; the results argue that the choice of electricity is vital in reducing emissions. Transporting the vehicle overseas by ship instead of by flight decreases emissions by about 82% to 97% within the various impact categories.   A sensitivity scenario was created for a hypothetical user in Barcelona, Spain, to better understand the influence of the selected lifetime and user behavior on the impacts. The results indicate that using an additional battery and thereby increasing the lifetime of the vehicle shows a 34% decrease in emissions per km driven within the lifetime of the motorcycle. Lastly, it is recommended whenever possible to source the numerous components of the vehicle closer to the assembly unit to reduce the transportation impacts incurred from transoceanic freight. / Företagens elfordonssegment har breddats och deras försäljning har ökat under det senaste decenniet. Den elektriska motorcykelsektorn växer snabbt, med förbättrad teknik på elektriska drivlinor, ökade räckvidder, laddningshastigheter och infrastruktur. Parallellt med den ökade försäljningen går elbatterisektorn snabbt framåt, vilket minskar miljöpåverkan från dessa fordon. Den konkurrensutsatta äventyrssportsektorn drar också nytta av att använda elektriska drivlinor med deras otroliga kraft-till-vikt-förhållande och omedelbara vridmoment. Fördelarna med att använda elfordon framför konventionella kan ses under användningsfasen, med noll avgasutsläpp och ren, tyst körning.  Men med expansionen av elmotorcykelsektorn som rullar ut nya tekniker och modeller, finns det osäkerheter om huruvida den övergripande livscykeln har minskat miljöpåverkan. Att hitta och förbättra de mest hållbara modellerna eller lösningarna innebär att man granskar dessa motorcyklars effekter på miljön, vilket är målet för CAKE 0 Emission AB, en svensk lättviktstillverkare av elmotorcykel.  Det aktuella projektet kommer att bedöma de potentiella miljöeffekterna av Kalk&, en terrängmodell av elektrisk motorcykel certifierad för användning på väg, designad och tillverkad av CAKE 0 Emission AB. För detta ändamål valdes Attributional Life Cycle Assessment som metoden för att studera effekten av en hel motorcykel under en livstid på 500 batteriladdningscykler, som används av en hypotetisk exempelanvändare i Stockholm, Sverige. Den potentiella miljöpåverkan är fokuserad på 12 kategorier med hjälp av metoden ReCiPe Midpoint (H).  Som förväntat av ett elfordon visar resultaten att effekterna huvudsakligen härrör från motorcykelns tillverkningsfas. Hotspots i tillverkningsfasen uppstår från att producera batteriet, elmotorn och de elektriska komponenterna som lampor, laddare och kablar. De material som används för konstruktion som har en hög andel av påverkan är koppar och aluminium. En annan miljömässig hotspot är tillverkningsprocessen för gjutning. Inom fordonsanvändningsfasen är effekten av att använda solenergi i Sverige för att ladda batterierna inte direkt intuitiv och har visat sig vara högre än den svenska elkortsmixen; resultaten talar för att valet av el är avgörande för att minska utsläppen. Att transportera fordonet utomlands med fartyg istället för med flyg minskar utsläppen med cirka 82% till 97% inom de olika påverkanskategorierna.  Ett känslighetsscenario skapades för en hypotetisk användare i Barcelona, Spanien, för att bättre förstå inverkan av den valda livslängden och användarbeteendet på effekterna. Resultaten indikerar att användning av ett extra batteri och därmed ökad livslängd på fordonet visar en 34% minskning av utsläppen per körd km under motorcykelns livslängd. Slutligen rekommenderas det när det är möjligt att köpa de många komponenterna i fordonet närmare monteringsenheten för att minska transportpåverkan från transoceanisk frakt.  Note: The abstract has been translated to Swedish from English using Google Translate

Sammanfattning på svenska: I nutiden, forskning och innovationer båda från akademi och industri försätter för att minska effekterna från klimatförändring. Ett av många viktiga område där utvecklingen fortsätter är litiumjonbatterier (LIB). På grund av den ökade energiförbrukningen i många områden (främst transporter) har ökat fossila bränsleförbrukningar och orsakat behovet av energi att lagras mer. Samhället kan inte bara fokusera på global miljövänlig batteriproduktion för att lösa detta problem. Samtidigt är det nödvändigt att koncentrera på hur man utvärderas begagnade batterierna som vi redan har. Återvinning av litiumjonbatterier har därför börjat få en ökad betydelse. Utmaningar för batteri återvinning är energi kravet för steg på processen och andra processer kan orsaka att skadliga ämnen släpps ut i naturen. Därför är det mycket viktigt att veta hur ett batteri påverkas av interna och externa förändringar från första till sista steget i återvinning och hur detta kommer att påverka de andra stegen. Detta examensarbete fokuserar på lösningsbaserade urladdningssteget i LIB-återvinning och syftar till att hitta den optimal temperatur genom att utforska möjliga förändringar som observerats på katodmaterialet. Inom ramen för projektet planerades temperaturoptimeringsstudien att göras genom att kombinera kemiska förändringar både inom och utanför batteriet i lösningsurladdningen. Detta är med en diskussion om särskilt fokus på att uppnå en hållbar återhämtning och kvaliteten på katodmaterialet. / In today's world, where global warming is felt in every sense, Research & Development (R&D) studies are continuing rapidly both in companies and in research networks to minimize its effects. One of the most important areas where developments continue is on lithium-ion batteries (LIBs). The increased energy consumption in many areas (mainly transportation), has increased fossil fuel consumption and caused the need for energy to be stored more. In this sense, focusing on only global-environmentally friendly battery production is insufficient to solve this problem. At the same time, it is necessary to concentrate on how to evaluate the used batteries that we already have. Therefore, lithium-ion battery recycling has begun to gain importance. Challenges for battery recycling are that some of the processes require energy inputs and others can generate harmful substances that require containment. Therefore, it is very important to know how a battery is affected by internal and external changes from the first to the last stage of recycling and how this will affect the other stages. This master thesis focuses on the solution discharge step in LIB recycling and aims to find the optimum temperature range for the discharge step of LIB recycling by exploration of the possible changes observed on the cathode material. In the scope of the project, the temperature optimization study was done by combining the chemical changes both inside and outside of the battery in the solution discharge. This is with a discussion of a particular focus on achieving a sustainable recovery and the quality of cathode material.

Traditional Lithium-Ion Batteries (LIBs) are a reliable and cost-efficient choice for energy storage. LIBs offer high energy density and low self-discharge. Recent developments in electric-based technologies push for replacing historically used Lead-Acid batteries with LIBs. However, LIBs do not yet meet the demands of modern technology. Silicon and graphene oxide (GO) have been identified as promising replacements to improve anode materials. Graphene oxide has a unique sheet-like structure that provides a mechanically stable, light weight material for LIB anodes. Due to its structure, reduced graphene oxide (rGO) is efficiently conductive and resistive to environmental changes. On the other hand, silicon-based anode materials offer the highest theoretical energy density and a high Li-ion loading capacity of various elements [20]. Silicon-based anodes that have previously been studied demonstrated extreme volumetric expansion over long cycles due to lithiation. Polysiloxane may be an interesting alternative as it is a Si-based material that can retain the high Li-ion loading capacity of Si while lacking the unattractive volumetric expansions of Si. Polymer derived ceramic-decorated graphene oxide anodes have been suggested to increase loading capacity, thermal resistance, power density, and mechanical stability of LIBs. Coupled with mechanically stable graphene oxide, polymer derived ceramic nanoparticle decorated graphene oxide anodes are studied to establish their efficiencies under operating conditions.

The research discussed is divided into two parts. The first part discusses the background work involved in preparation of the Li-ion cell testing stage. This includes the preparation of anodes using the doctor blade and a calendar mill, electrolyte preparation, test cell assembly, the Li-ion test cell design, and experiments performed to troubleshoot the cell. The second part deals with the cell testing experiments. Li-ion batteries are amongst the most promising rechargeable battery technology because of their high capacity and low weight. Current research aims at improving the anode quality to increase the capacity. The experiments discussed evaluate the traditional anode materials like SFG44 graphite and conducting grade graphite against the novel ones– and tin oxide (SnO2) based and carbon encapsulated tin based anodes. The solid electrolyte interphase formed on each anode was analyzed to understand the initial capacity fade leading to conditioning of the cell thus stabilizing its performance.

No description available.