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With a growing demand for electrical energy storage materials, lignin-derived carbon materials have received increasing attention in recent years. As a highly abundant renewable carbon source, lignin can be converted to a variety of advanced carbon materials with tailorable chemical, structural, mechanical and electrochemical properties through thermochemical conversion (e.g. pyrolysis). However, the non-uniformity in lignin structure, composition, inter-unit linkages and reactivity of diverse lignin sources greatly influence lignin fractionation from plant biomass, the pyrolysis chemistry, and property of the resulting carbon materials. To introduce a better use of lignocellulosic biomass to biofuels and co-products, it is necessary to find novel ways to fractionate lignin and cellulose from the feedstock at high efficacy and low cost. Deep eutectic solvent (DES) was used to extract lignin from high lignin-content walnut and peach endocarps. Over 90% sugar yields were achieved during enzymatic hydrolysis of DES pretreated peach and walnut endocarps while lignins were extracted at high yields and purity. The molecular weights of the extracted lignin from DES pretreated endocarp biomass were significantly reduced. The native endocarp lignins were SGH type lignins with dominant G-unit. DES pretreatment decreased the S and H-unit which led to an increase in condensed G-units, which may contribute to a higher thermal stability of the isolated lignin. Lignin slow pyrolysis was investigated using a commercial pyrolysis–GC/MS system for the first time to link pyrolysis chemistry and carbon material properties. The overall product distributions, including volatiles and solid product were tracked at different heating rates (2, 20, 40 ℃/min) and different temperature regions (100-200, 200-300 and 300-600 ℃). Results demonstrate that changes in reaction chemistry as a factor of pyrolysis conditions led to changes in yield and properties of the resulting carbon materials. Physical and chemical properties of the resulting carbon material, such as porosity, chemical composition and surface functional groups were greatly affected by lignin slow pyrolysis temperature and heating rate. Lignin-derived activated carbons (AC) were synthesized from three different lignin sources: poplar, pine derived alkaline lignin and commercial kraft lignin under identical conditions. The poplar lignin-derived ACs exhibited a larger surface area and total mesopore volume than softwood lignin-derived AC, which contribute to a larger electrochemical capacitance over a range of scan rates. The presence of oxygen-containing functional groups in all lignin-derived ACs, which participated in redox reaction and thus contributed to an additional pseudo-capacitance. By delineating the carbonization and activation parameters, results from this study suggest that lignin structure and composition are important factors determining the pore structure and electrochemical properties of the derived carbon materials. A 3-dimensional, interconnected carbon/silicon nanoparticles composite synthesized from kraft lignin (KL) and silicon nanoparticles (Si NPs) is shown to have a high starting specific capacity of 2932 mAh/g and a retaining capacity of 1760 mAh/g after 100 cycles at 0.72 A/g as negative electrode in a half-cell lithium-ion battery (LIB) test. It was found the elemental Si and C of the C/Si NPs were most likely linked via Si-O-C rather than direct Si-C bond, a feature that helps to alleviate the mechanical degradation from Si volume change and assure a sound electronic and ionic conductivity for enhanced electrochemical performance. EGA-MS and HC-GC/MS analyses suggest that the interaction of the Si, O and C can be tailored by controlling pyrolysis conditions. This study systematically investigated the interconnecting aspects among lignin source, pyrolysis chemistry, characteristics of the derived carbon materials and electrochemical performance. Such knowledge on the processing-structure-function relationships serves as a basis for designing lignin-based carbon materials for electrochemical energy storage applications.

Traditional electric vehicle and stationary battery systems use series-connected battery packs that employ centralized battery management and power processing architecture. Though, these systems meet the basic safety and power requirements with a simple hard- ware structure, the approach results in a battery pack that is energy and power limited by weak cells throughout life and most importantly at end-of-life. The applications of battery systems can benefit significantly from modular, scalable battery systems capable of advanced cell balancing, efficient power processing, and cost gains via reuse beyond first-use application. The design of modular battery systems has unique requirements for the power electronics designer, including architecture, design, modeling and control of power processing converters, and battery balancing methods. This dissertation considers the requirements imposed by electric vehicle and stationary applications and presents design and control of modular battery systems to overcome challenges associated with conventional systems. The modular battery system uses cell or substring-level power converters to combine battery balancing and power processing functionality and opens the door to new opportunities for advanced cell balancing methods. This approach enables balancing control to act on cell-level information, reroute power around weaker cells in a string of cells to optimally deploy the stored energy, and achieve performance gains throughout the life of the battery pack. With this approach, the integrated balancing power converters can achieve system cost and efficiency gains by replacing or eliminating some of the conventional components inside battery systems such as passive balancing circuits and high-voltage, high-power converters. In addition, when coupled with life prognostic based cell balancing control, the modular system can extend the lifetime of a battery pack by up to 40%. The modular architecture design and control concepts developed in this dissertation can be applied to designs of large battery packs and improve battery pack performance, lifetime, size, and cost.

Ces travaux de recherche ouvrent une nouvelle voie d’élaboration par voie sèche (sans utilisation de solvants organiques) d’électrodes pour batterie lithium-ion. Le procédé consiste en l’extrusion des différents constituants de l’électrode (liant, matière active et agent conducteur) en présence d’un polymère sacrificiel. Une première étude a porté sur le choix de l’agent conducteur et la nature du revêtement du substrat collecteur afin d’optimiser les propriétés électriques de l’électrode. Ensuite, afin d’une part justifier la cohésion des charges malgré un faible taux de liant et d’autre part expliquer certaines pertes de performances notamment en terme de conductivité électrique et ionique, nous avons étudié les interactions charges-polymère et mis en évidence la présence de polymère adsorbé/greffé à la surface des charge, connu sous le terme de « bound rubber ». Dans une dernière étude, nous avons enfin montré qu’il était possible de contrôler le taux de porosité de l’électrode permettant ainsi de formuler sans solvant une électrode répondant totalement au cahier des charges initial. En effet, des électrodes avec un taux de matière active supérieur à 80 %m (taux de charges global supérieur à 80 %vol), un taux de porosité de 40 %, une épaisseur inférieure à 100 μm, électriquement conductrices, et enfin de capacité initiale de 145 mA.h/g ont été réalisées / This study aims to find a new way of lithium-ion battery electrodes production using dry process. The production procedure consists on the extrusion of different compounds of the electrode (binder, active material and conductive agent) with a sacrificial polymer. First, a study was established to choose optimal conductive agent and coating material of the collector substrat in order to optimize electrical properties of the electrode. Then the interaction between charges and polymer was studied to justify charges cohesion despite the low amount of the binder and to explain some performances loss mainly in terms of ionic and electrical conductivity. This study revealed the presence of adsorbed / grafted polymer on the surface of charges, known as "bound rubber". Finally, we showed that electrode porosity could be controlled. In addition it was proved that it is possible to perform a dry electrode responding to initial specifications. In fact, electrodes with active material content greater than 80 wt% ( rate of global fillers greater than 80 vol % ), a rate of porosity of 40 vol % , a thickness less than 100 μm, high electrically conductive and finally a specific capacity of 145 mA.h/g were performed

<p>Lithium-ion batteries are regarded as the batteries that could potentially change the world. From consumer electronics and electric vehicles to energy storage systems and aerospace applications, Li-ion based batteries have become the norm. Although these batteries show a lot of promise to rid the world of several challenges in the future, there are still a few shortcomings of this battery that need to be addressed. It is also important to note the recent accidents caused due to the explosion of these lithium-ion batteries, to name a few: Samsung Galaxy Note 7 explosion, e-cigarettes battery explosion, overheating of lithium batteries present in Apple MacBook Pro laptop. This calls for a more reliable and accurate Battery Management System (BMS). One of the major shortcomings in today’s available battery management systems is the accuracy of the measurement of charge present in lithium-ion batteries, termed as State-of-Charge (SoC) and State-of-Energy (SoE) of the battery. </p> <p>To address this problem, a highly sensitive and a high-resolution system is developed to estimate the State-of-Charge based on the changes in impedance of a sensor coil which is caused due to the effect of Eddy Current Power Loss in the battery. The redox reaction taking place inside a battery suggest that lithium ions are exchanged back-and-forth between anode and cathode during an event of charging and/or discharging of the battery. This gives rise to change in electrical resistivity of the battery electrode materials. A sensor coil which is excited with an AC magnetic field induces Eddy currents on the internal components of the battery. Based on the change in resistivity of the electrode materials, eddy current and hence the power loss due to Eddy currents change. This in turn changes the complex impedance of the sensor coil, which is mapped to estimate the SoC of the battery. The results confirm the superiority of the proposed technique in terms of sensitivity, resolution, computational complexity and cost of the measured SoC in comparison with other existing methods of estimating SoC. This can be a potential method to estimate SoE of the battery as well. </p>

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京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17911号 / エネ博第283号 / 新制||エネ||59(附属図書館) / 30731 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 佐川 尚, 教授 八尾 健, 教授 石原 慶一 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20581号 / 工博第4361号 / 新制||工||1678(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 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第21432号 / 人博第870号 / 2018||人博||870(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 内本 喜晴, 教授 田部 勢津久, 教授 吉田 鉄平 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21787号 / 工博第4604号 / 新制||工||1717(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 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM