Li-ion batteries have gained great popularity among researchers and practitioners as an environmentally friendly energy storage solution for more environmentally friendly electric vehicles (EVs). However, because of the increased demand for Li-ion battery-powered EVs, and some issues with battery design, legislation, collection and sorting, recycling, and material recovery, achieving sustainable mobility through the circularity of Li-ion batteries is a major challenge. This study aims to identify the challenges as well as develop strategies for enhancing the circularity of Li-ion batteries in Sweden. Following a systematic literature review, two primary research questions were investigated: 1) what are the current challenges and opportunities for the circular economy in lithium-ion battery end-of-life management? 2) how the circularity of LIBs in Sweden could be enhanced? This study employed PEST and SWOT analysis, as well as 11 interviews with industry experts and researchers are performed, to determine the strengths, weaknesses, opportunities, and threats in the circularity of lithium-ion batteries in Sweden. Following that, various strategies were developed to address the identified challenges and improve the circular economy of these batteries. Finally, the developed strategies are validated through expert interviews, and various recommendations are outlined. The study's findings are significant and can assist policymakers, investors, and industry professionals concerned with the circularity of lithium-ion batteries in developing appropriate decisions and better planning for the Swedish transportation sector.

Utveckling av det moderna samhället och den fortsatt accelererande energiintensiva tillvaro människan lever i sätter stor press på klimatet. För att nå de hållbarhetsmål FN satt upp som bland annat innebär minskade utsläpp och effektivare energianvändning krävs krafttag i det globala energisystemet. För att öka andelen modern och ren energi krävs att sol- och vindkraft prioriteras. Ett stort problem med dessa energikällor är dess intermittenta produktion vilken alstrar oregelbunden elektricitet och ställer nya krav på elnätet. För att underlätta implementering av förnybara energikällor på det nationella elnätet och i mindre energisystem undersöks i den här rapporten de förutsättningar som finns för att integrera batterienergilagringssystem i kombination med intermittenta energikällor. Rådande förutsättningar redogörs för i en omfattande litteraturundersökning där bland annat elnätets funktion, lovande batteriteknologier, ekonomiska incitament för batterienergilagring och framtidspotential undersöks. Ett globalt engagemang för att öka andelen förnybar energi med hjälp av batterienergilagring i det globala energisystemet identifieras. Vidare visas batterienergilagringssystem har stor potential att minimera den belastning intermittenta energikällor har på elnätet. Potentialen begränsas i nuläget av rådande politiska styrmedel och elmarknadens utformning då en småskalig elproducent idag gynnas av att direkt mata ut överskottsel på elnätet istället för att använda energilagring. Med en växande andel intermittent elproduktion förväntas minskade begränsningar och batterienergilagring kopplat till elproduktion bli mer lönsamt. / The development of the modern society and the global continuously accelerating energy intensive way of living is putting stress on the climate. In order to achieve the UNs set of sustainability goals, including reduced emissions and more efficient use of energy, vigorous actions in the global energy system is required. To increase the share of clean and modern energy generation a larger quantity of solar and wind power is required. Due to weather dependency these resources generate intermittent electricity which will put new challenges on the grid.   To facilitate the implementation of intermittent energy sources on the national grid and in smaller energy systems this report aims to investigate current prerequisites on integrating battery energy storage systems and intermittent resources to increase the share of clean energy sources in the power system. Current prerequisites are presented as the result of an extensive literature study where the electrical grid, promising battery technologies, financial incentives for battery energy storage and future potential is examined.   A global commitment to increase the share of renewable energy sources using battery energy storage system in the global energy system is identified. Furthermore, battery energy storage systems are shown to have great potential in limiting the negative impact of intermittent energy sources on the electrical grid. This potential is currently being limited by existing political control means and the design of the electricity market such that small producers are benefitted by directly supplying the grid with excess electricity instead of using energy storage. With a growing share of intermittent power generation these limitations are expected to ease and battery energy storage systems in connection with power production becoming more profitable.​

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This study sought to improve the performance of Si-based anodes through the use of hierarchically structured electrodes to provide the nanoscale framework needed to accommodate large volume changes while controlling the interfacial area – which affects solid-electrolyte interphase (SEI) formation. To accomplish this, electrodes were fabricated from vertically aligned carbon nanotubes (VACNT) infiltrated with silicon. On the nanoscale, these electrodes allowed us to adjust the surface area, tube diameter, and silicon layer thickness. On the micro-scale, we have the ability to control the electrode thickness and the incorporation of micro-sized features. Treatment of the interfacial area between the electrolyte and the electrode by encapsulating the electrode controls the stabilization and reduction of unstable SEI. Si-VACNT composite electrodes were prepared by first synthesizing VACNTs on Si wafers using photolithography for catalyst patterning, followed by aligned CNT growth. Nano-layers of silicon were then deposited on the aligned carbon nanotubes via LPCVD at 200mTorr and 535°C. A thin copper film was used as the current collector. Electrochemical testing was performed on the electrodes assembled in a CR2025 coin cell with a metallic Li foil as the counter electrode. The impact of the electrode structure on the capacity at various current densities was investigated. Experimental results demonstrated the importance of control over the superficial area between the electrolyte and the electrode on the performance of silicon-based electrodes for next generation lithium ion batteries. In addition, the results show that Si-VACNT height does not limit Li transport for the range of the conditions tested.

The increased demand of energy storage systems and electric vehicles on the market result in high demand of lithium-ion batteries. As a lithium-ion battery manufacturer, Northvolt runs quality tests on the products to assess their performance, life and safety. Batteries that are tested are most often behaving as expected, but sometimes deviations occur. Anomaly detection is today most often performed by plotting and comparing produced data to other test-data to find which parameters that are deviating. The purpose of this thesis is to automatize anomaly detection and a proposed solution is to use state-of-the-art machine learning methods. These include using supervised and unsupervised machine learning. Before applying machine learning, the feature engineering is presented. It describes what parameters are extracted from the experiment data sets. Then the supervised machine learning framework is described. For the unsupervised machine learning, a principal component analysis is presented to locate deviations. This thesis also presents a differential capacity analysis, as this could be incorporated with the features in the future. The results shows that the subset of labeled data for supervised learning is too small to produce a model that predicts future deviations. The extracted features are also used in the principal component analysis, where the results show deviations (outliers) and aid targeting the anomalies. These can then be used to determine the root-cause of particular anomalies and mitigate future deviations.

With an increasing demand for sustainable transport solutions, there is a demand for electrified vehicles. One way to store energy on board an electrified vehicle is to use a lithium-ion battery (LIB). This battery technology has many advantages, such as being rechargeable and enabling reasonably high power output and capacity. To ensure reliable operation of LIB:s, the battery management system (BMS) must be designed with regards to the electrochemical dynamics of the battery. However, since the battery ages over time, the dynamics changes as well. It is possible to predict ageing, but some ageing mechanisms can occur randomly, e.g. due to variations of circumstances during manufacturing, and variations of battery user choices. Hence, by monitoring ageing mechanisms in situ, the BMS can adapt accordingly, similar to a closed loop control system. One ageing mechanism in LIB:s is lithium plating. This mechanism signifies when Li ions are electrochemically deposited as metal onto the negative electrode of the LIB during charging, and can induce other ageing mechanisms, such as gassing or electrolyte reduction. The present project has investigated a method for detecting Li plating in situ after its occurrence by both analysing the voltage change over time during open-circuit voltage (OCV) periods after charging and monitoring battery swelling forces. Results show a correlation between a high probability of Li plating and the appearance of a swelling force peak and an OCV plateau. However, results also show a possible correlation between the onset of Li plating and the onset of the swelling force peak, while also showing a greater detectability of the force signal compared to the electrochemical signal. Furthermore, the present results show that the magnitudes of both signals are probably related to the amount of plated Li. The amount of irreversibly lost Li from plating is shown to have a possible correlation with accumulation of swelling pressure. However, to further validate the feasibility of these two signals, more advanced analysis is required, which was not available during this project. / Med en ökande efterfråga på hållbara transportlösningar så finns det ett behov av elektrifierade fordon. Ett sätt att lagra energi ombord ett elektrifierat fordon är att använda et litium-jon-batteri. Denna batteriteknologi har många fördelar: t.ex. är dessa batterier återladdningsbara, och de kan leverera höga uteffekter samtidigt som de kan ha ett stort energiinnehåll. för att säkerställa en säker drift av litium-jon-batterier måste batteriets styrsystem vara designat med hänsyn till den elektrokemiska dynamiken inuti batteriet. Dock åldras batteriet med tiden, vilket innebär att denna dynamik ändras med tiden, vilket innebär att styrningen av batteriet måste anpassa sig till denna föråldring. Det är möjligt att förutspå åldring av batterier, men vissa åldringsmekanismer kan ske slumpartat, t.ex. via slumpmässiga förändringar i tillverkningsprocessen av batteriet, eller variationer i användningen av batteriet. Genom att därmed bevaka dessa åldringsmekanismer in situ så kan styrsystemets algoritm anpassa sig utmed batteriåldringen, trots dessa slumpartade effekter. En åldringmekanism hos litium-jon-batterier är s.k. litiumplätering. Denna mekanism innebär att litium-joner elektrokemiskt pläteras i form av metalliskt litium på ytan av litium-jon-batteriets negativa elektrod. Mekanismen kan också inducera andra åldringsmekanismer, t.ex. gasutveckling eller elektrolytreduktion. Detta projekt har undersökt en metod för att detektera litiumplätering in situ efter att plätering har skett, genom att både analysera öppencellspänningens (OCV) förändring med tiden direkt efter uppladdning samt analysera de svällande krafterna som uppstår under uppladdning av batteriet. Resultaten visar på en korrelation mellan en hög sannolikhet för litiumplätering och observationen av en topp i svällningskraft och en platå i OCV-kurvan. resultaten visar också en möjlig korrelation mellan påbörjandet av litium-plätering och påbörjandet av toppen i svällningskraft. Vidare visar även resultaten ett troligt samband mellan signalernas magnitud och mängden pläterat litium. Slutligen visar resultaten också ett möjligt samband mellan irreversibelt pläterat litium och ett svällningstryck som ackumuleras med varje uppladdningscykel. Dock krävs det en validering med mer avancerade analysmetoder för att säkerställa användningsbarheten av dessa två signaler, vilket ej var möjligt inom detta projekt.

The rapid development of the lithium-ion battery industry is currently driving down sys-tem costs as a result of maturing processes. Decreasing system costs enables additional revenue streams and applications, provided through li-ion battery storage, to be ex-plored. EAM Solar, a Norwegian solar utility company with operational solar power plants across the globe, seeks to build and operate a solar power plant (SPP) in the Dutch region of Leeuwarden. This thesis investigates whether an SPP with an installed capacity of 16.1MW, can be economically profitable when utilizing li-ion battery energy storage systems (BESS) for arbitrage and time-shift of subsidized solar power in order to avoid large(r) grid-connection costs while accepting grid transmission limits. Literature, environment parameters and estimates from the industry was combined with financial data from the client and collaborators, such as a battery manufacturer, to create viable and realistic economic evaluations.The literature study provided information for relevant parameters such as the life cycle of a battery, which enabled a realistic modeling procedure regarding cyclic and calendric degradation, charge/discharge behavior, end of life terms and overall efficiencies. It was modelled quantitatively in Stella Architect and Microsoft Excel to obtain economical and financial indicators, such as Net Present Value (NPV) & Internal Rate of Return (IRR), to subsequently provide recommendations on whether to make the investment.Results show worse economic outcomes for li-ion BESS investments compared to the original investment of a stand-alone SPP, even when arbitrage was implemented as a cost recovery mechanism and with a smaller grid-connection cost. Furthermore, it is shown that a stand-alone BESS only used for arbitrage is unlikely to become profitable in the foreseeable future at this location or in a similar market mainly due to large in-vestment costs combined with substantial fees associated with access to the day-ahead electricity auction in the Netherlands, EPEX Spot NL. It is also shown that in spite of the lower grid connection for a SPP combined with a li-ion BESS, a 20-25% decrease in battery investment cost is required for the investment to yield similar rate of returns as a stand-alone SPP investment. The model developed in this thesis can be considered to be a tool for evaluating similar systems in the future with minor modifications, espe-cially as the market- and technology environment evolves. / Den snabba utvecklingen utav litium-jonindustrin för batteritillverkning har kraftigt dri-vit ner systemkostnader som ett resultat av mer mogna processer. Sjunkande systemkost-nader möjliggör upptäckande av både nya intäktskällor och användningsområden för li-tium-jonbatteri. EAM Solar, ett norskt solkraftföretag som äger ett flertal solkraftverk världen över, är just i planeringsstadiet för att bygga och underhålla ett nytt kraftverk i den nederländska staden Leeuwarden. Denna uppsats undersöker om ett solkraftverk med en kapacitet på 16.1 MW kan vara lönsamt tillsammans med ett batterisystem som ska användas för att lagra el när överföringsgränsen är nådd, samt för arbitragehandel. Förhoppningen från klientens sida var att den mindre nätanslutning kunde användas tillsammans med ett batterisystem för undvika vissa investeringskostnader. Litteratur, lokala parametrar och kalkyler från industrin kombinerades med finansiella data från klienten och samarbetspartners som batteritillverkare för att skapa trovärdiga och real-istiska resultat.Litteraturstudien gav information om relevanta parametrar såsom livscykeln för ett bat-teri, vilket möjliggjorde en realistisk modelleringsprocedur gällande cyklisk och tidsan-passad degradering, laddning- och urladdningsbeteende, slutvillkor för användning och generella effektiviteter. Modellen modellerades sedan kvantitativt i Stella Architect och i Microsoft Excel för att få fram finansiella indikatorer vilka gav en rekommendation om en investering skulle göras eller ej.Resultaten visade sämre ekonomiska resultat för litium-jonbatteri kombinerat med ett solkraftverk jämfört med endast ett solkraftverk för sig själv, detta även om både ar-bitrage och lagring av överskottselektricitet används för att öka intäkterna kombinerat med en liten anslutning till det nationella nätet. Utöver detta visar det sig att ett batte-risystem som endast används för arbitragehandel är långt ifrån lönsamt för sig själv, och detta lär inte ändras under den närmaste tiden, i alla fall inte på en marknad som den nederländska. Anledningarna till detta är alltför höga investeringskostnader kombinerat med relativt höga avgifter för att ens få handla på den nederländska elmarknaden, EPEK Spot NL. För att nå lika resultat för ett solkraftverk med eller utan batterisystem krävs det, i det bästa fallet, en minskad investeringskostnad på 20-25%. Det ska dock nämnas att det krävs en mindre nätanslutning om ett batterisystem används, vilket är anled-ningen till att de finansiella resultaten är relativt lika, utan detta skulle alla system med batteripaket ge betydligt sämre värde. När uträkningar gjordes på batterisystem som endast används för arbitragehandel gav dem negativa ekonomiska resultat i samtliga fall, oberoende av batteristorlek. Det är dock viktigt att notera att modellen som skapades för denna uppsats är enkel att använda i framtiden. När parametrar ändras är det simpelt att justera modellen för att undersöka precis samma fall i framtiden.

This project investigates the viability of using reconditioned batteries, which have lost part of their original capacity while powering electric vehicles (EVs), to minimize the expenses of fast-charging infrastructures under the three charging scenarios where fast-charging mode is likely to be needed the most. The analysis is conducted for the Spanish scenario and considers the retail electricity tariff that best suits the requirements of a FCS. The economic analysis is performed on an annual basis and is tackled with an optimization algorithm, formulated as a mixed-integer linear programming problem and run on MATLAB. The expected lifetime of the ESS, being made of reused automotive cells, is estimated with a semi-empirical approach, using an iterative process and implemented in MATLAB. A sensitivity analysis is conducted on three input parameters that were identified to have a considerable impact on the system design and performance.   Overall, results show that with current figures energy storage integration in FCSs is viable as it effectively reduces the infrastructure expenses in all scenarios. Peak-shaving is identified as the main source of cost savings while demand shifting is not effective at all. The latter is further discussed in the sensitivity analysis and some considerations are elaborated. The most profitable scenario for storage integration is the case of a fast-charger located in a urban environment while, surprisingly, the lowest cost savings are obtained in the highway case. The sensitivity analysis illustrates the impact and effects that electricity prices and specific cost of both the power converter and the second-life batteries produce on the optimal system design. Moreover, charging demand profiles are deeply analyzed and their main implications highlighted.

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第24632号 / 工博第5138号 / 新制||工||1982(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 作花 哲夫, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM