Rozprawy doktorskie na temat „Lithium-free”

Current batteries for soldier systems rely on many different standard power source sizes, shapes and weights. The integration of power sources into space-limited platforms and to fit to a soldier correctly is difficult. Conventional layer by layer manufacturing approaches are still relied on for battery production. 3D battery systems offer the potential to produce batteries that are bespoke to equipment size and shape whilst maintaining the advantages of the thin film battery manufacturing techniques. There are several techniques available to produce these 3D battery systems and this thesis will look at the application of on one such technique, electrophoretic deposition to lithium iron phosphate (LFP) battery positive electrode materials. Electrophoretic deposition is a technique where an electric field is used to deposit particles from a colloidal suspension onto a conducting surface. This thesis will present the development of the electrophoresis technique for flat plate samples of the LFP through deposition from a suspension of LFP particles in iso propyl alcohol with a metal salt. The results of studies using cyclic voltammetry and impedance spectroscopy will then be presented and discussed in relation to deposition parameters and to gain a greater understanding of the resistances present between the LFP particles in the binder and carbon additive-free electrodes.

Many countries including Sweden are planning to replace fossil fuel-based vehicles with electric vehicles. This is one of the main reasons that companies all over the world are investing more and more money in the development of lithium-ion batteries, for electric vehicles. There are several different risks with the conventional lithium-ion batteries including the high flammability of the electrolytes, which can lead to high heat release rate, risk of explosion and high toxicity in the form of hydrogen fluoride gas. The hydrogen fluoride is lethal even at low concentration. These potential risks are based on the structure of the flammable electrolytes inside the lithium-ion batteries. Because of that, there is a big interest in finding an electrolyte with similar battery performance and better fire properties as compared with the conventional electrolytes commercially available on the market.   The intent with this work is to investigate the fire properties of different halogen-free electrolytes. The two newly developed salts Li[MEA] & Li[MEEA] as well as the available salt Li[BOB] will be compared with the commercially used halogen-containing electrolyte based on lithium hexafluorophosphate (LiPF6) salt.   Physical and electrochemical properties of these electrolytes such as solubility in different organic solvents, density, viscosity, ionic conductivity and electrochemical window will be studied in the first step. The electrolytes showing the most promising electrochemical properties will then be further investigated regarding fire properties, heat release rate, flash point and toxicity. The electrolytes will be compared with the conventional electrolyte containing LiPF6.   Li[BOB] was not dissolved in the solvents with the strongest dissolving properties, therefore it was not further tested. The electrolytes that were tested regarding fire properties were Li[MEA] and Li[MEEA] with the organic solvents of ethylene carbonate and dimethyl carbonate. Ionic liquid was also added to Li[MEEA] to investigate how it affected the fire properties for the electrolyte.   When examine the heat release rate for the newly developed salts, as well as LiPF6, it was observed that the highest peaks were similar to each other. The combustion time for the electrolyte containing LiPF6 was noticeable shorter than for the other three electrolytes. This is likely due to the fluorine content in LiPF6. The electrolytes undergoing the cone calorimeter test in this work was not charged so therefore the peaks of the heat release rate may look different. For further studies, it could be of interest to construct a complete lithium-ion battery using these electrolytes to see how the battery cells and the electrolytes behave in different set of charges.   Another essential point, is the ignition time that showed varied times for the tests containing Li[MEEA] together with the organic solvents and with the added ionic liquid. This is an interesting result that probably can be explained by the homogeneity of the electrolyte. The homogeneity was only verified with the help of the human eye and therefore it may not be fully dissolved.   The flashpoint for the different mixtures of electrolytes showed values of interest where the electrolyte containing ionic liquid that showed the lowest flashpoint. This was unexpected concerning that these types of additives are common for improving the fire resistance capacity.   The key aspect discussed when analyzing the result from the FTIR spectroscopy was how the Li[MEA], Li[MEEA] and LiPF6 salts varied. The ones that did not have any fluorine in its structure resulted in production of carbon dioxide. However, the electrolyte containing fluorine resulted, as expected, in values of hydrogen fluorine and carbon dioxide but also other combustion products that was hard to determine.   These salts and electrolytes need to be further studied and tested to see if it is possible to use them in an actual lithium-ion battery. Besides further tests of the salts and ionic liquid tested in this work, it is important that the work with conventional and newly developed electrolytes aims for improvements in fire resistance as well as toxicity.
Många länder inklusive Sverige planerar att byta ut fordon som använder fossila bränslen mot elfordon. Detta är en av huvudanledningarna till att företag runt om i världen satsar mer och mer pengar på att utveckla litiumjonbatterier för elfordon. Litiumjonbatterier medför en del risker såsom hög värmeutveckling, brandfarliga vätskor, risk för explosion och toxiska gaser samt produceringen av vätefluorid. Redan vid låga koncentrationer är vätefluoriden dödlig. Riskerna baseras på strukturen av elektrolyten som finns i litiumjonbatteriet. På grund av dessa risker så är det intressant att utveckla en elektrolyt som har liknande batteriegenskaper men bättre brandegenskaper än de elektrolyter som finns och används idag.   I detta arbete har brandegenskaper för olika halogenfria elektrolyter testats. De två nyutvecklade salterna Li[MEA] & Li[MEEA] har tillsammans med det existerande saltet Li[BOB] jämförts med det kommersiella saltet litium hexafluorfosfat (LiPF6) som används till många elektrolyter i dagens litiumjonbatterier.   De fysiska och elektrokemiska egenskaperna såsom löslighet i organiska lösningsmedel, densitet, viskositet, jonkonduktiviet och elektrokemiskt fönster har testats för elektrolyterna i den första delen av arbetet. Elektrolyterna som uppvisade de mest lovande elektrokemiska egenskaper har även testats med avseende på brandegenskaperna, så som värmeutveckling, flampunkt och toxicitet. Elektrolyterna jämfördes mot den vanligt förekommande elektrolyten som innehåller litium hexafluorfosfat.   Saltet Li[BOB] löstes inte i lösningsmedel med bra lösningsegenskaper, vilket var anledningen till att det inte genomfördes ytterligare tester på den. Elektrolyterna som det genomfördes tester på avseende på brandegenskaper innehöll Li[MEA] och Li[MEEA] tillsammans med de organiska lösningsmedlen etylenekarbonat och dimetylkarbonat. För Li[MEEA] tillsattes det även jonvätska för att undersöka hur jonvätskan påverkar brandegenskaperna för elektrolyten.   När värmeutveckling för det nyutvecklade salterna och LiPF6 undersöktes, så uppvisade de liknande värden. Anmärkningsvärt var dock att förbränningstiden för LiPF6 varade under en kortare period i jämförelse med de tre andra elektrolyterna. En trolig orsak till detta är att LiPF6 innehåller fluor. Elektrolyterna som provades i konkalorimeter i detta arbete var ej laddade, vilket kan medföra att värmeutvecklingen kan se annorlunda ut vid ett laddat tillstånd. För framtida studier kan det vara intressant att konstruera ett komplett litiumjonbatteri, för att se hur elektrolyterna fungerar och påverkas, beroende på laddningsnivå.   Antändningstiden för Li[MEEA] blandat med de organiska lösningsmedlen tillsammans med jonvätska varierade mycket. Detta är ett intressant resultat, som förmodligen kan förklaras av homogeniteten på elektrolyten. Homogeniteten verifierades enbart okulärt, vilket inte säkerställer att jonvätskan har löst sig fullständigt i elektrolyten.   Resultat för flampunkten för det olika elektrolyterna var intressant, då elektrolyten som innehöll jonvätska visade på lägst flampunkt. Detta var oväntat då tillsatser som jonvätska brukar förbättra brandmotståndet.   Resultatet för FTIR-spektroskopin analyserades för att se hur Li[MEA], Li[MEEA] och LiPF6 skiljde sig åt. De elektrolyter som inte innehöll fluor, producerade bara koldioxid. Medans elektrolyten som innehöll fluor producerade, som väntat, vätefluorid och koldioxid, men även andra gaser som var svåranalyserade.   De framtagna elektrolyterna i detta arbete behöver studeras vidare och fler tester bör genomföras för att se om det finns en möjlighet att använda dem i faktiska litiumjonbatterier. Förutom att testa elektrolyterna i just detta arbete är det viktigt att forskningen kring brandegenskaper och toxiska egenskaper för elektrolyter fortsätter i framtiden.

O presente trabalho está relacionado com o desenvolvimento e análise do desempenho eletroquímico de eletrodos compósitos do tipo nonwoven também chamados de free-standing binder/metal-free electrodes, em eletrólito líquido orgânico que contem íons de lítio. Os eletrodos de excelente resistência mecânica, livre de metais e binder, e que podem conter vários miligramas dematerial eletroativo por cm3, são constituídos por substratos de fibras de carbono derivado de poliacrilonitrila, e a carga eletroativa composta por nanotubos de carbono de parede múltipla (NTC) e nanotubos de MnO2 (NT). Foram utilizados dois tipos de substrato (denominados aqui de feltro e tecido de carbono) de diferentes condutividades eletrônicas e geometrias tridimensionais. O recobrimento das fibras de carbono dos nonwovens com NTC foi realizado por decomposição química de vapor (CVD) mantendo-se constante as variáveis operacionais, o que resultou em NTC do mesmo tipo para todas as amostras e um bom controle da massa depositada. O MnO2 foi incorporado por eletrodeposição em eletrólito aquoso, esse método garantiu um bom controle de massa eletrodepositada de NT. Os eletrodos obtidos foram caracterizados estruturalmente empregando-se microscopia de varredura (MEV), difração de raios-X e microscopia Raman. Para análise de desempenho eletroquímico e mecanismo de armazenagem/conversão de energia nos eletrodos empregadas as técnicas de voltametria e cronopotenciometria cíclicas. Os resultados mostram que os eletrodos compósitos são híbridos, podem atuar como capacitores e eletrodos de baterias de íons lítio. As metodologias aplicadas se mostram extremamente reprodutíveis reprodutivas e controláveis. Depedendo das composições e combinações foi possível obter capacidades específicas associadas com armazenagem/estocagem de lítio em altas densidades de corrente (A/g) na janela de potencial de 0,005 - 3,5V vs Li/Li+ (por exemplo, 800 mAh/g em 1 A/g, taxa C-rate = 1,25C, 400 mAh/g em 2,66A/g, taxa C-rate = 5C). A eficiência faradaica para o primeiro ciclo carga/descarga variou entre 83% e 54%, dependendo da quantidade de MnO2 e da corrente aplicada. Foi observado que é possível melhorar ainda mais os resultados com adição de outros constituintes, como por exemplo, a adição de partículas de prata (<1 % em peso). Neste caso os eletrodos forneceram eficiência faradaica de 83%, 1.100 mAh/g em 1,7A/g, em taxa C-rate = 1,66C e 550 mAh/g em 2,8A/g em taxa C-rate = 5C). Em termos de capacitância os compósitos também se mostram muito positivos. Valores de capacitância da ordem de 180F/g foram facilmente obtidos em tempos de descarga de 58s e num intervalo de potencial em relação ao Li/Li+ (~3,05 V vs H2/H+) de 1,4 a 3,8V vs Li/Li+, o que permite gerar densidade de energia e potência da ordem de 63 Wh/kg e 3,6 kW/kg respectivamente. Os eletrodos estudados podem atuar como eletrodo em baterias de íons lítio e em dispositivos de capacitores, o que significa que pode ser útil para o desenvolvimento de sistemas híbridos de armazenamento/conversão de energia, particularmente, de sistemas híbridos bipolar bateria-supercapacitor.
The present work is correlated with the development and electrochemical analisys of a nonwoven kind of electrode, also called as free-standing binder/metal-free electrodes, into lithium-ion liquid organic electrolyte, whereas the constituents are the substrate made of carbon fiber derived from carbonization of polyacrylonitrile, and the electroactive material which are defective multi-walled carbon nanotubes (MWCNT) and MnO2 nanotubes. Two types of nonwoven substrates (here denominated felt and cloth) with different electronic conductivity and three-dimensional geometry were employed. MWCNT coating of the nonwoven carbon fibers was achieved with chemical vapor decomposition (CVD) of methanol at same growth conditions, which resulted in electrodes with same type of MWCNT and a good control of the deposited mass. MnO2 was incorporaded by electrodeposition in aqueous electrolyte and this methodology was found appropriate to provide electrodes with same MnO2 NT loading, although the structural phase of MnO2 was affect by nonwoven substrate type. The robusts electrodes able to support several miligrams of electroactive material per cm3 obtained were structurally characterized using scanning electron microscopy (SEM, TEM), X-ray diffraction and Raman microscopy. It was employed cyclic voltammetry at different scan rate and chronopotentiometry (discharge/charge curves at galvanostatic conditions) aiming the understanding of the electrochemical performance and mechanism of energy storage/conversion of MnO2/MWCNT coated nonwoven electrodes. The results show that the composite electrode is hybrid, can act like capacitor or lithium ion battery electrode. It can provide very high specific capacity associated with storage/extraction of Li same in elevated gravimetric current density of A/g in the potential window of 0.005-3.5V vs Li/Li+ (e.g 800 mAh/g at 1 A/g, rate = 1,25C, 400 mAh/g at 2,66A/g, rate = 5C). The Faradic efficiency measure during the first charge/discharge cycle was between 83% to 54% depending on amount of MnO2 constituent and applied current. It was also observed a gain in the electrochemical performance of MnO2/MWCNT coated nonwoven electrode with Ag nanoparticles addition (about 1% wt). With presence of Ag constituent into the composites nonwovens it was found for instance 83% of Faradic efficiency at 1st discharge/charge cycle, 1,100 mAh/g at 1,7A/g rate = 1,66C and 550 mAh/g at 2,8A/g rate = 5C. In terms of capacitance the nonwoven were able to provide values like 180 F/g during 58s in high voltage window (1.4-3.8V vs LI/Li+) which correspond to energy and power density of 63 Wh/kg e 3.6 kW/kg, respectively. The electrodes developed in the present study could therefore act both as an electrode for Li intercalation and for capacitors devices, which means that it can be useful for the development of hybrid energy storage/conversion systems, particularly, bipolar battery-supercapacitor hybrid single.

Lithium-ion batteries (LIBs) have been widely used as the most popular rechargeable energy storage and power sources in today’s portable electronics, electric vehicles, and plug-in hybrid electric vehicles. LIBs have gained much interest worldwide in the last three decades because of their high energy density, voltage, rate of charge and discharge, reliability, and design flexibility. I am exploring the possibility of developing battery manufacturing technologies that would lower the cost, reduce the environmental impact, and increase cell performance and durability. This dissertation is focused firstly on understanding the effect of mixing sequence (the order of introducing materials) and optimizing the electrode fabrication for the best electrochemical performance, durability, lower cost, and improve the existing manufacturing processes. The electrode system consists of active material, polymer binder, conductive agent, and solvent. I have investigated four different mixing sequences to prepare the slurries for making the positive electrode. The key sequence-related factor appears to be whether the active material and conductive agent are mixed in the presence of or prior to the introduction of the binder solution. The mixing sequences 1, 2, 3, and 4 were optimized, and the rheological behavior of the slurries, morphology, conductivity, and mechanical and electrochemical properties of electrodes were investigated. Slurries from sequences 1 and 4 show different rheological properties from 2 and 3. The amount of NMP required to achieve a comparable final slurry viscosity differed significantly for the sequences under study. The sequence 1 shows better long-term cycling behavior than sequences 2, 3 and 4. This study quantifies the link between electrode slurry mix parameters and electrode quality. Secondly, a new method of making lithium-ion battery electrodes by adapting an immersion precipitation (IP) technology commonly used in membrane manufacturing was developed and demonstrated. The composition, structure, and electrochemical performance of the electrode made by the IP method were compared favorably with that made by the conventional method. The toxic and expensive organic solvent (NMP) was captured in coagulation bath instead of being released to the atmosphere. The IP electrodes show an excellent performance and durability at potentially lower cost and less environmental impact. Thirdly, I have developed and demonstrated a solvent-free dry-powder coating process for making LiNi1/3Mn1/3Co1/3O2 (NMC) positive electrodes in lithium-ion batteries, and compared the performance and durability of electrodes made by the dry-powder coating processes with that by wet-slurry coating processes. The technology that has been used is the electrostatic spray deposition (ESD) process. This process eliminates volatile organic compound emission, reduces thermal curing time from hours to minutes, and offers high deposition rates onto large surfaces. The long-term cycling shows that the dry-powder coated electrodes have similar performance and durability as the conventional wet-slurry made electrodes.

La microstructure et la macrostructure du polybutadiène jouent un rôle essentiel dans les propriétés thermomécaniques du matériau, qui est largement utilisé dans la fabrication de pneumatiques. Grâce à son contrôle sur le processus de polymérisation et à son caractère vivant, la polymérisation anionique permet d’obtenir avec précision une grande variété d'architectures polymères, offrant ainsi la possibilité de moduler les propriétés du matériau. Cependant, la polymérisation anionique du butadiène est largement dominée par l’utilisation d’amorceurs à base lithium. La demande croissante du lithium, en particulier dans le secteur du stockage de l’énergie, impose aujourd’hui de proposer des systèmes anioniques sans lithium comme alternativedurable, et économiquement favorable. Par ailleurs, la synthèse de polybutadiènes avec une teneur élevée en unités 1,4-trans est peu étudiée en polymérisation anionique. Cette thèse propose des systèmes multi-métalliques à base de calcium pour d’une part une chimie sans lithium, et d’autre part. la synthèse de polybutadiènes stéréospécifiques 1,4-trans de manière contrôlée et vivante. Différentes synthèses de complexes de calcium, puis plusieurs systèmes d’amorçages novateurs sont proposés. En particulier, les systèmes calcium-lithium, calcium-magnésium, calcium-aluminium et calcium-sodium sont étudiés
The microstructure and macrostructure of polybutadienes play an essential role in the thermomechanical properties of the material, which is widely used in tires manufacture. Thanks to its control over the polymerization process and its living character, anionic polymerization enables to obtain with precision a wide variety of polymer architectures, thus offering the possibility of modulating the material's properties. However, the anionic polymerization of butadiene is largely dominated by the use of lithium-based initiators. With the growing demand for lithium, particularly in the energy storage sector, it is important to offer lithium-free anionic systems as a more sustainable and economically favorable alternative. It's worth mentioning that the synthesis of polybutadiene with a high content of 1,4-trans units is poorly studied in anionic polymerization. This thesis proposes calcium-based multi-metallic systems for a lithium-free chemistry on the one hand, and the controlled andliving synthesis of stereospecific 1,4-trans polybutadienes on the other. Different syntheses of calcium complexes followed by a number of novel initiating systems are proposed. In particular, calcium-lithium, calcium-magnesium, calcium-aluminium and calcium-sodium systems are studied

Au cours de cette thèse, un nouvel électrolyte polymère gel pour la réalisation de microbatteries au lithium a été développé. Le gel a été préparé par « confinement » d’une phase de N-propyl-N-méthylpyrrolidinium bis(fluorosulfonyl)imide (P13FSI) et de LiTFSI dans un réseau semi-interpénétré (sRip) de polymère (PVdFHFP/ réseau de POE). L’électrolyte gel a tout d’abord été optimisé et étudié en termes de propriétés physicochimiques et de transport ionique en fonction de sa composition. Ensuite, des batteries Li/LiNi1/3Mn1/3Co1/3O2 ont été assemblées en utilisant l’électrolyte sRip. Les performances ont par ailleurs été comparées aux systèmes de références utilisant l’électrolyte à base de POE ou de PVdF-HFP. Outre ses propriétés améliorées par rapport au PVdF-HFP et au réseau de POE (propriétés mécaniques, confinement), l’électrolyte sRip est compatible avec le procédé de dépôt de l’électrode négative en lithium par évaporation sous vide. L’électrolyte sRip optimisé a donc été utilisé pour fabriquer une nouvelle génération de microbatteries en s’affranchissant de l’électrolyte céramique, le LiPON, afin d’abaisser la résistance interne. Les microbatteries Li/sRip gel/LiCoO2 délivrent une capacité nominale stable de 850 μAh à C sur 100 cycles à 25°C
In this thesis, a new polymer gel electrolyte was prepared and optimized for Li based microbatteries. The gel consisted of an ionic liquid based phase (P13FSI/LiTFSI) confined in a semi-interpenetrating polymers (sIPN) network (PVdF-HFP/crosslinked PEO). sIPN electrolytes were prepared and optimized according to the PVdFHFP/ crosslinked PEO ratio and the liquid phase fraction. Furthermore, the sIPN electrolyte was used as an electrolyte in Li/LiNi1/3Mn1/3Co1/3O2 battery. The performances of the battery (specific capacity, efficiency, cyclability) were determined and compared to batteries using a crosslinked PEO or PVdF-HFP based gel. Such a thin and stable sIPN electrolyte film enabled the preparation of Li based microbatteries using thermal evaporation deposition of lithium directly conducted on the sIPN electrolyte film. This assembly (Li/sIPN) was therefore used to prepare a LiCoO2/sIPN gel/Li quasi solid-state microbattery. This microbattery showed a stable nominal capacity of 850 μAh for over 100 cycles of charge and discharge under 1 C rate at 25°C

Over the last decades the struggle for indigenous rights has accomplished great achievements within international law. In relation to development projects and resource extraction on indigenous lands, the principle of Free, Prior and Informed Consent (FPIC) has gained increased recognition and is today expressed as an important instrument to realize indigenous peoples’ right to self-determination. Nevertheless, empirical evidence have identified power asymmetries as one of the major obstacles for effective and meaningful FPIC implementation. This study investigates how power asymmetries emerge and affect the right to self-determination through the four FPIC requirements. Based on field research and by applying a relational approach, the study investigates a case of mining activities in northwestern Argentina where indigenous communities currently experience an increased interest in lithium deposits on their lands from transnational corporations. The study shows how relations characterized by dependency and clientelism create a situation where actors hold unequal power positions which permeate all FPIC requirements severely undermining the principle’s potential to fulfill its purpose. Lastly, based on the findings the study argues substantial underpinnings in terms of necessary preconditions are needed if FPIC are to be able to ensure self-determination.

The optimisation of existing chemistries by the introduction of environmentally friendly materials and the simplification of the device production process are intriguing challenges to promote the future widespread diffusion of LIBs. Moreover, the recent development of the next-generation electronic devices promoted a new research field for the modification of the current systems into light, flexible and/or micro-sized device. The enhancement of mechanical properties through the introduction of flexible electrodes will enable LIBs to be embedded into various functional systems in a wide range of innovative products such as smart cards, displays and implantable medical devices. Moreover, the optimisation of the electrolyte by moving towards an all-solid-state configuration will offer adaptability to various designs and stressful mechanical handling, as well as enhance cell safety and reliability. During the three years of the Ph.D. course, the attention was focused on the optimisation of innovative materials for Li-ion batteries as well as the development of easily up-scalable procedures for the production of electrodes and polymer electrolytes. The basic idea was to start from eco-friendly materials to develop simple, low-cost and easily adaptable processes in order to propose innovative solutions for LIBs with a wide range of possible applications. Moreover, during my experimental activities, I considered the performances and the cycling stability of Li-ion batteries, by studying the mechanisms related to the capacity fade of lab-scale batteries and also by analysing commercial Li-ion batteries for automotive application. The results of the research work are presented in this thesis (Chapters 4-7) following an introductory section that provides the general information needed to follow the discussions (Chapters 1-3). The experimental research work presented in Chapter IV was carried out in collaboration with the Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) in Grenoble (France). A well-known natural material such as cellulose was exploited for the production of innovative low-cost and easily recyclable electrodes for Li-ion batteries. A simple aqueous filtration process, based on a well-known industrialised paper-making technology, was developed and the electrodes (graphite-based anodes and LiFePO4-based cathodes) produced and partly characterized in Grenoble by Dr. Lara Jabbour were electrochemically studied in our Labs in Politecnico di Torino. In particular, cellulose fibres (FBs) were used as natural binder for the production of paper-like electrodes obtained without addition of any synthetic binder and/or solvent and showing electrochemical performance comparable to those produced with the same active materials by a standard process. In Chapter V, results are reported regarding a newly developed procedure where a methacrylic-based polymer electrolyte is directly formed in situ at the interface with the electrodes. Exploiting the versatile nature of UV-induced free-radical photo-polymerisation, novel ready-to-use multiphase electrode/electrolyte composites (MEEC) were developed in which the electrode is conformally coated by the polymer electrolyte. This “one-shot” process was successfully applied to enhance the cycling performances of two nanostructured materials conceived for microbattery application, such as Cu2O (in collaboration with CSHR@Polito IIT research institute in Torino) and V2O5 (in collaboration with Prof. Mustarelli’s group in University of Pavia), prepared in the form of thin films and proposed respectively as anode and cathode. The proposed one-shot process, thanks to the intimate interfacial contact between electrodes surface and electrolyte obtained by in situ process, induced a huge effect of stabilization thus improving the cycling stability of both the nanostructures. All along Chapter VI, the problems related to the assembling of complete Li-ion cells, starting from two well performing electrodes, are progressively discussed and valuable solutions are proposed. A strong capacity fade was initially found, thus the possible causes were studied also considering the failure mechanisms proposed in the literature. Several measures were adopted to improve the cycling stability, considering the effect of all the different cell components as well as the effects of both charging protocol and cell apparatus. Moreover, due the knowhow progressively achieved on the intimate characteristics of complete Li-ion cells and their assembly, even thanks to a three months stage at ENEA Casaccia Research Centre of Rome, the installation of a 10 m2 dry room was personally followed at our Electrochemistry Research Group Labs in Politecnico di Torino and the results obtained are presented in the same Chapter VI. These results include the realisation of an all-paper Li-ion battery with the cellulose-based electrodes and paper hand-sheets as separator. Finally, the cycling stability and the failure prediction issue was studied for a 53 Ah commercial battery. The results obtained, by means of different standard reference tests, are reported in Chapter VII. The commercial battery was also disassembled in the controlled atmosphere of an Ar-filled dry box in order to study the system structure and characterise the various components. A testing protocol was personally developed and the results obtained allowed to evaluate the commercial battery based on the performances requested for HEV and EV application. In particular, an easy measure of the internal resistance was developed, by opportunely modulating the measured parameters, and the obtained results were found to be very useful in directly predicting the cell failure which is fundamental in practical application.

The deposition of boron oxide (B₂O₃) films on silicon substrates is of significant interest in microelectronics for ultrashallow doping applications. However, thickness control and conformality of such films has been an issue in high aspect ratio 3D structures which have long replaced traditional planar transistor architectures. B₂O₃ films are also unstable in atmosphere, requiring a suitable capping barrier for passivation. The growth of continuous, stoichiometric B₂O₃ and boron nitride (BN) films has been demonstrated in this dissertation using Atomic Layer Deposition (ALD) and enhanced ALD methods for doping and capping applications. Low temperature ALD of B₂O₃ was achieved using BCl₃/H₂O precursors at 300 K. In situ x-ray photoelectron spectroscopy (XPS) was used to assess the purity and stoichiometry of deposited films with a high reported growth rate of ~2.5 Å/cycle. Free-radical assisted ALD of B₂O₃ was also demonstrated using non-corrosive trimethyl borate (TMB) precursor, in conjunction with mixed O₂/O-radical effluent, at 300 K. The influence of O₂/O flux on TMB-saturated Si surface was investigated using in situ XPS, residual gas analysis mass spectrometer (RGA-MS) and ab initio molecular dynamics simulations (AIMD). Both low and high flux regimes were studied in order to understand the trade-off between ligand removal and B₂O₃ growth rate. Optimization of precursor flux was discovered to be imperative in plasma and radical-assisted ALD processes. BN was investigated as a novel capping barrier for B₂O₃ and B-Si-oxide films. A BN capping layer, deposited using BCl₃/NH₃ ALD at 600 K, demonstrated excellent stoichiometry and consistent growth rate (1.4 Å/cycle) on both films. Approximately 13 Å of BN was sufficient to protect ~13 Å of B₂O₃ and ~5 Å of B-Si-oxide from atmospheric moisture and prevent volatile boric acid formation. BN/B₂O₃/Si heterostructures are also stable at high temperatures (>1000 K) commonly used for dopant drive-in and activation. BN shows great promise in preventing upward boron diffusion which causes a loss in the dopant dose concentration in Si. The capping effects of BN were extended to electrochemical battery applications. ALD of BN was achieved on solid Li-garnet electrolytes using halide-free tris(dimethylamino)borane precursor, in conjunction with NH₃ at 723 K. Approximately 3 nm of BN cap successfully inhibited Li₂CO₃ formation, which is detrimental to Li-based electrolytes. BN capped Li-garnets demonstrated ambient stability for at least 2 months of storage in air as determined by XPS. BN also played a crucial role in stabilizing Li anode/electrolyte interface, which drastically reduced interfacial resistance to 18 Ω.cm², improved critical current density and demonstrated excellent capacitance retention of 98% over 100 cycles. This work established that ALD is key to achieving conformal growth of BN as a requirement for Li dendrite suppression, which in turn influences battery life and performance.

To develop high energy density lithium ion batteries, the use of new electrode materials is required. Germanium is among the possible alternatives to the most commonly used anode, graphite (372 mAh/g), thanks to its four-times higher theoretical gravimetric capacity (1600 mAh/g). Here is presented a two-step method to produce a binder-free porous germanium anode, depositing the semiconductor on metallic substrates by means of Plasma Enhanced Chemical Vapour Deposition (PECVD) and subsequently performing an electrochemical etching with hydrofluoric acid to create a porous structure. The Ge-based electrode attained a capacity of 1250 mAh/g at a current rate of 1C (1C=1600 mA/g) and retained a stable capacity above 1100 mAh/g for more than 1000 cycles tested at different C-rates up to 5C. Both deposition and etching techniques are scalable for industrial production, whose fields of application could be aerospace or medical applications, due to the high cost of germanium as a raw material.
Per sviluppare batterie agli ioni di litio ad alta densità energetica, è necessario l’utilizzo di nuovi materiali elettrodici. Il germanio è una delle possibili alternative all’anodo più comunemente impiegato, la grafite (372 mAh/g), grazie alla sua capacità gravimetrica teorica quattro volte maggiore (1600 mAh/g). In questo lavoro viene presentato un processo in due fasi per realizzare un anodo in germanio poroso privo di legante (binder), realizzando film di semiconduttore su substrati metallici mediante deposizione chimica da fase vapore assisitita da plasma (PECVD) ed effettuando successivamente un attacco elettrochimico con acido fluoridrico per creare una struttura porosa. L’elettrodo in germanio poroso ha raggiunto una capacità di 1250 mAh/g ad una velocità di carica/scarica pari ad 1C (1C = 1600 mA/g) mantenendo, inoltre, una capacità stabilmente superiore a 1100 mAh/g per più di 1000 cicli a diversi C-rate fino a 5C. Sia la tecnica di deposizione che quella di attacco chimico sono scalabili per la produzione industriale, i cui possibili campi di applicazione sono il settore aerospaziale o medico, a causa dell’elevato costo del germanio come materia prima.

Natural graphite from cheap and abundant natural sources is an attractive anode material for lithium ion batteries. We report on modifications of such a common natural graphite, whose electrochemical performance is very poor, with solutions of (NH4)2S2O8, concentrated nitric acid, and green chemical solutions such of e.g. hydrogen peroxide and ceric sulfate. These treatments resulted in markedly im-proved electrochemical performance (reversible capacity, coulombic efficiency in the first cycle and cycling behavior). This is attributed to the effective removal of active defects, formation of a new dense surface film consisting of oxides, improvement of the graphite stability, and introduction of more nanochannels/micropores. These changes inhibit the decomposition of electrolyte solution, pre-vent the movement of graphene planes along a-axis direction, and provide more passage and storage sites for lithium. The methods are mild, and the uniformity of the product can be well controlled. Pilot experiments show promising results for their application in industry.

Notre travail a consiste a synthetiser et caracteriser de nouveaux materiaux radicalaires de trois familles differentes (neutres, cations et anions), pour les applications de la magnetometrie par resonance paramagnetique electronique (rpe). Trois nouvelles phtalocyanines de lithium octa-substituees ont ete preparees. Les etudes rpe ont montre que ces composes ne possedent pas d'avenir pour nos applications. Nous avons prepare deux nouveaux radicaux cations du perylene avec comme anion associe, teof#5# et ((teof#5)h)#. Les bonnes caracteristiques de ce dernier font de lui un candidat a fort potentiel pour la magnetometrie. Plusieurs radicaux tcnq ont ete synthetises et caracterises par rpe. De ces etudes, deux materiaux se sont reveles particulierement interessants pour les applications haute temperature. Une nouvelle classification des radicaux est proposee: les radicaux avec effet d'oxygene et les radicaux avec effet de recuit

This thesis covers synthesis and characterisation of TiO2 nanotubes and TiO2 / Li4Ti5O12 composite nanotubes. The aim was to build batteries with high areal capacity and good rate capability. TiO2 nanotubes were synthesized by two step anodization of titanium metal foil and the composite electrodes were synthesized through electrochemical lithiation of TiO2 nanotubes. To improve the battery performance the TiO2 nanotubes were annealed at 350 °C in air atmosphere, while the composite electrodes were annealed in argon at 550 °C. The longest TiO2 nanotubes were measured to 42.5 μm. The 40 μm long nanotubes displayed an areal capacity of 1.0 mAh/cm2 and a gravimetric capacity of 89 mAh/g. Nanotubes having a length of 10 μm had an areal capacity of 0.33 mAh/cm2 and a gravimetriccapacity of 130 mAh/g. When cycled at high rates, 10C, the capacity of the 40 μm nanotubes was 0.25 mAh/cm2, using a current density of 9.3 mA. The capacity of the 40 μm long nanotubes were higher than for the 10 μm long, but the increase was not proportional to the increase in length. A composite electrode was successfully synthesized and was found to have a capacity of 0.25 mAh/cm2 at a rate of C/5.

Ce travail de thèse a été réalisé dans le cadre du programme européen INNOSHADE, dont l'objectif était la réalisation de dispositifs électrochromes à coloration neutre. Cette coloration neutre est le résultat de l'association dans un même dispositif de la couleur marron de films à base d'oxyde de nickel avec celle bleue de films d'oxyde de tungstène ou de PEDOT. Nos recherches ont été orientées vers des films minces d'oxyde de nickel modifié contenant des ions nickel trivalent, alliant porosité et désordre structural. Deux techniques de dépôt ont été utilisées : l'ablation laser et le trempage-retrait (dip-coating). Des processus de coloration et de décoloration de ces films en milieux liquides ioniques hydrophobes lithiés et non lithiés, faisant intervenir la participation d'anions tels que TFSI-, ont été mis en évidence pour la première fois dans cette thèse. Les dispositifs tout solides correspondants présentent des efficacités optiques élevées et une bonne durabilité.

O-acyl-N-benzyllactamides are obtained in good yield by reaction of 4-benzyl-5-methyl-1,3-oxazolidine-2,4-diones with Grignards reagents and with lithium alkyls. Three alkanes and two ethers were oxidised with ozone in dichloromethane solution or in aqueous pH 3 suspension. Cyclodecane and cyclododecane were converted into the corresponding cycloalkanones. n-decane was converted into a mixture of isomeric n-decanones and carboxylic acids. An ester was formed from the ethers. Hence, one of the methylene groups of these substrates is generally converted into a carbonyl group. Some of these reactions have preparative value. The oxidation of naphthalene in dichloromethane or acetonitrile with excess ozone gives phthalic aldehyde, 2-formyl benzoic acid and phthalic anhydride. Small amounts of the (E)- and (Z)-isomer of 3-phenyl-(2-formyl)-propenal and are also observed in some cases. The reaction is faster in acetonitrile than in dichloromethane owing to the higher solubility of ozone in the former solvent. The reaction is faster on lowering the temperature because of the increase of the concentration of ozone in solution at lower temperature. With a 1:1 or a 1:2 naphthalene:ozone ratio high conversion and low selectivity for the anhydride is observed. The ozonation of cyclohexane in dichloromethane or acetonitrile gives cycloxexanone, cyclohexanol and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The ozonation of N-phenylmorpholine in dichloromethane or acetonitrile produced a lactame and a diformylderivative. These products derive from the attack of ozone at the heterocyclic ring. The reaction mechanism has been investigated by DFT calculations which show that the reaction occurs through the insertion of ozone at the carbon-hydrogen bond of a methylenic group of the morpholine ring. The regioselectivity is due to the to the significantly lower energy barrier calculated for the attack of ozone in α to nitrogen than in α to oxygen. Also, the energy barrier decreases with increasing the polarity of the solvent, accounting for the higher reaction rate observed for the reaction carried out in acetonitrile than in dichloromethane. The ozonation of trans- and cis-decalin in dichloromethane or acetonitrile gives the corresponding 9-hydroxydecalinns, 2- and 3-decalones and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The N,N bis(salicylidene)ethylenediaminocobalt(II) catalysed oxidative carbonylation of para-substituted aromatic primary amines at 100 °C in methanol gives carbamates in high yields. In presence of excess dimethylamine also N-aryl-N’,N’-dimethylureas are formed. In methylene chloride moderate yields in isocyanate are obtained. 1-methylbenzylamine gives the carbamate and the urea in high yield. i-propylamine gives only the urea. An α-aminoalcohol gives a 1,3-oxazolidin-2-one. Aliphatic secondary amines react faster and give carbamates in methanol and ureas in methylene chloride. The turnover frequency is also measured in two cases.

Detta projekt syftar till att undersöka den termiska rusningsprocessen hos ett litiumjonbatteri med en fluorfri elektrolyt och jämföra den med en kommersiellt använd fluor-innehållande elektrolyt. Battericellerna innehöll silikon-grafit som anod och LiNi0.6Mn0.2Co0.2O2 (NMC622) som katod. Den fluorfria elektrolyten var baserad på litium bis(oxalato)borat (LiBOB) i organisk lösning med additivet vinylen karbonat(VC). Det jämfördes med en fluor-innehållande elektrolyt med LiPF6 i samma organiska lösning tillsammans med VC och fluoroetylene karbonat (FEC). De termiska stabilitetstesterna utfördes med Accelerating Rate Calorimetry (ARC) och Differentiell svepkalorimetri (DSC). Både knappceller och pouchceller har undersökts med hjälp av ARC. Trots flera försök med olika uppställning kunde den termiska rusningen inte bli detekterad för någon av celltyperna, med slutsatsen att en störremängd aktivt material behövs. Istället användes DSC för att undersöka de termiska reaktionerna hos batteri-komponenterna. Resultaten visade att anoden var mer termisk stabil med den fluorfria elektolyten, medan samma elektrolyt visade mindre termisk stabilitet på katoden. Vidare undersökningar behövs dock för bekräftelse av katoden.
This project aims to investigate the thermal runaway process of fluorine-free lithium ion battery cells and to compare this with a commercially used fluorinated electrolyte. The cells consisted of a silicon-graphite composite anode and a LiNi0.6Mn0.2Co0.2O2(NMC622) cathode. The non-fluorinated electrolyte used was based on lithiumbis(oxalato)borate (LiBOB) in organic solvents with the additive vinylene carbonate(VC). Moreover, the fluorinated electrolyte consisted of LiPF6 in the same organic solvents together with VC and fluoroethylene carbonate (FEC). The thermal stability measurements have included Accelerating Rate Calorimetry (ARC) and Differential Scanning Calorimetry (DSC). Moreover, both coin cells and pouch cells have been examined by ARC. However, thermal runaway could not be detected for either type of cells, concluding that a greater amount of active material was needed. In order to measure the thermal reactions of the battery components, DSC was used. These results concluded that the anode was more thermally stable with a non-fluorinated electrolyte. However, the thermal stability appeared to be lower for the cathode, therefore, further investigation is needed for confirmation of the cathode.

La réalisation du stockage d'énergie et le retour de l'approvisionnement en énergie est crucial pour plusieurs applications (VE, téléphones portables, ordinateurs portables). Des électrodes épaisses avec des matériaux inactifs minimisés dans la batterie globale peuvent améliorer la densité d'énergie des batteries lithium-ion. Spark Plasma Sintering est une technique de densification avancée qui a été utilisée pour préparer des électrodes épaisses en quelques minutes. L'approche de modèle est adoptée pour préparer des électrodes poreuses avec des tailles de pores et des morphologies interconnectées bien contrôlées. Ici, des particules de microsize de chlorure de sodium sont utilisées comme agent de gabarit pour créer des pores à l'intérieur des électrodes épaisses. Ces électrodes frittées sans liant sont auto-supportées, ce qui contribue à augmenter la densité énergétique des batteries lithium-ion. Les performances électrochimiques des batteries demi- et pleines révèlent une capacité surfacique spécifique remarquable (20 mA h cm-2), qui est 4 fois supérieure à celle des électrodes de 100 μm présentes dans les batteries Li-ion classiques (5 mAh cm) -2). L'étude morphologique 3D est réalisée par micro-tomodensitométrie pour obtenir des valeurs de tortuosité et des distributions de tailles de pores conduisant à une forte corrélation avec leurs propriétés électrochimiques. Ces résultats démontrent que le couplage entre le procédé de matriçage de sel et le frittage par plasma d'étincelles est également appliqué pour la fabrication d'électrodes épaisses en utilisant d'autres matériaux actifs et que différentes configurations de cellules sont également proposées
The achievement of energy storage and return of energy supply is crucial for several applications (EVs, cellphones, laptops). Thick electrodes with minimized inactive materials in the overall battery can improve the energy density of lithium ion batteries. Spark Plasma Sintering is an advanced densification technique has been used to prepare thick electrodes in minutes. The templating approach is adopted for preparing porous electrodes with interconnected well-controlled pore sizes and morphologies. Here, sodium chloride microsize particles are used as a templating agent to create pores inside the thick electrodes. These sintered binder-free electrodes are self-supported that helps to increase the energy density of lithium ion batteries. The electrochemical performances of half and full batteries reveal a remarkable specific areal capacity (20 mA h cm−2), which is 4 times higher than those of 100 μm thick electrodes present in conventional tape-casted Li–ion batteries (5 mA h cm−2). The 3D morphological study is carried out by micro computed tomography to obtain tortuosity values and pore size distributions leading to a strong correlation with their electrochemical properties. These results demonstrate that the coupling between the salt templating method and the spark plasma sintering is also applied for thick electrodes fabrication using other active materials and also different cell configurations are proposed

碩士
國立交通大學
電控工程研究所
100
Technological products have continuously made progress since the beginning of the 21st century. With the advancement of Integrated Circuit Design and associated technique, the electrical equipments, which were large before, can be minimized nowadays. The principle and the purpose of these technological products are various, but there is a common trait, that is, they use rechargeable batteries as the power source. For that reason, the batteries used as the power source dominate the utilization of the portable devices and many battery management systems (BMS) emerge as a result. Using Lithium-ion battery becomes the mainstream of power source of portable devices due to its exclusive characteristics. However, how to fast and effectively charge the battery becomes one of the top BMS issues after rechargeable batteries are increasingly important. On the other hand, the charging strategy of constant-current/constant voltage utilized by the chargers in circulation is that the current is pre-decided to charge the battery. However, we couldn’t adjust the charging current according to the battery’s condition. With aging or different situation of battery, the charging time can’t be optimized by applying same charging current to the batteries with varied aging of batteries during constant current period; what is even worse, the charging time would be prolonged. At the moment, the development target of battery charger is how to adjusting charging current in order to optimize charging time in different state of batteries. In this thesis, an intelligent aging-free Lithium battery charger is proposed to decide the current in constant current period without providing electrochemistry data when every time the charger is turned on. It achieves the purpose of fast charging by adjusting the current in constant current period according to aging effect and internal resistance of the battery and decreases charging time by 27.4%. Therefore, the charging time can be optimized by this intelligent aging-free Lithium Battery charger.

博士
國立臺灣科技大學
化學工程系
106
Abstract Inventing new materials and battery design to enable rechargeable lithium battery with higher capacity, cycle life, efficiency, and energy density is of paramount importance. In fulfilling these principles’ Lithium metal is the most promising anode material in lithium metal battery due to its highest theoretical capacity (3860 mAh/g), lowest reduction potential (-3.04 V) vs Li/Li+(V) and lowest density (0.534 g/cm3). To realize lithium metal rechargeable secondary battery, tremendous research efforts exerted and a remarkable progress has been made. However, the safety challenge, low Coulombic efficiency, shallow cycling conditions, and poor cycle life limit the practical application. To overcome those bottleneck challenges and effectively use lithium metal anode, an anode-free lithium metal battery designed. The new battery architecture constructed in discharge state by pre-storing lithium in the cathode and lithium metal anode generated in-situ on copper current collector while charging. Realizing such a battery is an effective strategy to boost energy density, minimize cost and ease cell fabrication with safety. However, like lithium metal battery in-situ plated lithium grow to moss and whiskers like lithium dendrites on bare copper current collector upon cycling resulting from uneven Li deposition and inability of solid electrolyte interface (SEI) to control the stress exerted by dendritic Li growth. The formation of lithium dendrite induces low Coulombic efficiency, infinite volume expansion, electrolyte decomposition and even penetration of separator and short circuiting cell. To realize a dendrite free high energy density in-situ plated battery new strategies such as nanostructured current collector anode, using stable SEI layer forming additives, high concentration electrolytes, optimizing electrolyte solvent and using lithium rich or pre-lithiated cathodes to compensate lithium loss can be implemented. Our strategy will allow the newly battery design to gain widespread acceptance in electric vehicles, electronics, communication devise as a result of its simplicity to scale up, low cost, increase safety and a means to potential market. In our first work, copper current collector coated with polyethylene oxide (PEO) film to stabilize lithium deposition and enhance cycle life. More importantly, the PEO film coating reinforces solid electrolyte interface (SEI) layer, encapsulate lithium film on copper and regulate the inevitable reaction of lithium with electrolyte. The modified electrode showed stable cycling of lithium with an average Coulombic efficiency of ~100% over 200 cycles and low voltage hysteresis (~30 mV) at a current density of 0.5 mA/cm2. Moreover, the anode-free battery proved experimentally by integrating it with the LiFePO4 cathode into a full cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with average Coulombic efficiency of 98.6% and 49% capacity retention at 100th cycle. In contrary a capacity retention of ~35% obtained when bare copper paired with the same cathode. These impressive enhanced cycle life and capacity retention results from the synergy of PEO film coating and high electrode-electrolyte interface compatibility. Our result opens up a new route to realize the anode-free batteries by modifying the copper anode with PEO polymer to achieve ever demanding yet safe interfacial chemistry and controlled dendrite formation. The second motivation of this dissertation focus on engineering copper current collector with ultra-thin graphene layer with chemical vapor deposition (CVD) method as artificial layer to suppress lithium dendrite. Multilayer graphene film with superior strength, stability, and flexibility to facilitate uniform lithium-ion flux makes it an excellent choice to stabilize electrode interface. The new designed copper electrode with size higher than cathode size paired with commercial LiFePO4 cathode (mass loading ~12 mg/cm2), and ensures the first cycle discharge capacity of 147 and 151 mAh/g for bare and multilayer graphene protected electrode respectively which then alleviate the big hurdle (initial capacity loss) in an in-situ plated battery. After 100 round trip cycles, bare and multilayer graphene film protected copper retain ~ 46 and 61 % of their initial capacity respectively in an ether-based electrolyte at 0.1C rate. In final work, the viability of rechargeable in-situ plated lithium metal battery on bare copper anode demonstrated by using lithium bis(trifluoromethanesulfonyl)imide(LiTFSI) salt in dimethoxy ethane(DME)/1,3-dioxolane (DOL) solvent and 4 wt % LiNO3 additive. The reduction of LiNO3 into lower order nitrite LixNOx and lithium nitride (Li3N) facilitate the formation of robust solid electrolyte interface (SEI) layer with high mechanical strength and stability. By using Cu/LiFePO4 cell without any pre-lithiation, the feasibility of anode-free lithium metal battery could deliver areal capacity of ~1.60 mAh/cm2 in its first cycle and retains about 0.863 mAh/cm2 capacity even at 100th cycles. In contrary, Cu/LFP cell in ether electrolyte without LiNO3 showed a rapid capacity fading. Moreover, by using a 4 wt % graphite composite in LiFePO4 cathode the 100th and 200th cycle capacity retention improved to 65.6 % and 33 % of its initial capacity respectively when cycled at 0.2 mA/cm2.

博士
國立臺灣科技大學
化學工程系
107
Lithium (Li) metal is regarded as an ultimate negative electrode (anode) for energy storage system due to its very high specific capacity (3860 mAh g-1), the most negative electrochemical potential (-3.04V vs. Standard hydrogen electrode, SHE) and a low gravimetric density (0.534 g cm−3). Rechargeable lithium metal batteries (LMBs) have been extensively studied since the last four decades and received high attention currently due to increasing demand for high energy density batteries for consumer electronics, electric vehicles (EVs), and smart grid energy storage. To realize lithium metal rechargeable secondary batteries, tremendous research efforts exerted and remarkable progress has been made. However, the safety challenge, low Coulombic efficiency, shallow cycling conditions, and poor cycle life limit the practical application. To overcome these challenges and effectively use lithium metal anode, an anode-free (AFB) is battery designed. The new battery configuration is constructed by pre-storing lithium in the cathode and lithium metal anode generated in-situ onto anode current collector while charging. AFB is an effective strategy to uplift the energy density, reduce cost and simplify cell fabrication process with safety should be taken into account. Anode-free batteries (AFBs) are impressive and recent phenomena in the era of energy storage devices due to their high energy density and relative ease of production compared to the traditional Lithium metal batteries (LMBs). However, dendrite formation during plating and stripping and low coulombic efficiency (CE) are the main challenges that impede practical implementation of these batteries. Here we report an extremely stable dual-salt electrolyte, 2M LiFSI+1M LiTFSI (2FSI+1TFSI)) in DME/DOL (1:1, v/v), system in comparison to the single salt 3M LiTFSI (3TFSI) in DME/DOL (1:1, v/v), to effectively stabilize AFB composed of LiFePO4 cathode and bare Cu-foil anode for the first time. The electrolyte stabilized anode-free cell with the configuration Cu||LiFePO4 via reductive decomposition of its anions and enabled the cell to be cycled with CE of 98.9% for 100 cycles. This results from the formation of stable, ion conductive and electrically insulating inorganic components rich Solid Electrolyte Interface (SEI) layer on the surface of in-situ deposited Li-metal that blocks the undesirable parasitic reaction between the deposited Li and the electrolyte. Thus, aforesaid SEI mitigates the formation of dead lithium and dissolution of the in-situ deposited Li surface during repeated cycling and prolongs cycle life of the battery. The combined effect of concentrated salt electrolyte and resting protocol on the cyclic performance of anode free battery (AFB) is evaluated systematically. In-situ deposition of Li in the AFB configuration in the presence of a concentrated electrolyte containing fluorine donating salt and resting the deposit at higher voltage enables the formation of stable and uniform SEI. The SEI intercepts undesirable side reaction between the deposit and solvent in the electrolyte and reduces electrolyte and Li consumption during cycling. The synergy between the laboratory prepared concentrated 3M LiFSI in the ester-based electrolyte and our resting protocol significantly enhanced cyclic performances of AFBs in comparison to the commercial carbonate-based dilute electrolyte, 1M LiPF6. Benefitting from the combined effect, Cu||LiFePO4 cells delivered excellent cyclic performance at 0.5 mA/cm2 with average CE of up to 98.78% retaining reasonable discharge capacity after 100 cycles. Furthermore, the AFB can also be cycled at a high rate up to 1.0 mA/cm2 with a high average CE and retaining encouraging discharge capacity after 100 cycles. The fast cycling and stable performance of these cells are attributed to the formation robust, flexible and tough F-rich conductive SEI on the surface of the in-situ deposited Li by benefiting from the combined effect of the resting protocol and the concentrated electrolyte. A condescending understanding of the mechanism of SEI formation and material choice could facilitate the development of AFBs as a future advanced energy storage devices. The effects of lithium imide and fluorinated lithium orthoborate dual-salt electrolytes of different salt composition in a mixture of ether and carbonate solvents on the cycling stability of anode free batteries are comparatively investigated. The compositions of the dual-salt electrolyte were optimized using the anode free battery configuration and found that the 0.9M LiTFSI+0.3M LiDFOB in FEC/TTE (2:3, v/v) is the best among all. The electrochemical performance of AFB in this optimized dual-salt electrolyte is intensively investigated in comparison to the single salt electrolyte, 1.2M LiTFSI, in the same solvent ratio. Accordingly, the cyclic performance of Cu||NMC cell in the dual-salt electrolyte surpassed that of the single salt. The relative better performance of the anode free battery in the dual salt electrolyte is attributed to the co-existence of dual ion (TFSI- and DFOB-) in the electrolyte, which enhanced conductivity and introduces entirely new interphases via preferential decomposition mechanisms. The newly formed interface is stable, ionically conductive, and be able to intercept parasitic side reaction between the solvent in the electrolyte and deposited Li by blocking electron and solvent flow towards the deposit. As a result of the unique interfacial chemistry brought by this dual-salt system, this electrolyte supports an unprecedented CE (98.6%) and capacity retention (63%) in 4.5V Cu||NMC cell at 0.5 mA/cm2 and >27% improvement over the single salt electrolyte after 50 cycles.

碩士
國立清華大學
材料科學工程學系
105
In recent years, as the popularity rate of consumer electronic product increases, the demand of secondary energy storage device increases. Among them, lithium ion battery(LIB) which possessed outstanding energy density and cycle life has gotten much attention. For the commercial anode materials of LIB, lithium titanate(LTO)metal oxide anode has shown 300 times the cycle life of carbon materials and higher charge/discharge rate, making it stand out from the market. In recent research, vanadium pentoxide(V2O5) has revealed the same lithium storage mechanism as LTO and has the higher amount of lithium intercalation than LTO, it’s more suitable for anode material. Moreover, amorphous V2O5 gets more reversible specific capacity than crystalline state. In this thesis, we directly deposited amorphous V2O5 on porous nickel foam current collector by hydrothermal process. The LIB test demonstrates that after 50 cycles, the reversible specific capacity can reach 884 mAh/g and the retention can be maintained at 94.21% under low current density 0.5C. However, when the current density increases to 1C level, the retention decreases merely to 77.74% after 50 cycles. By taking differential capacity curves into comparison, we find the effect of charge/discharge rate that affects the low-voltage specific capacity. In contrast, the degradation of retention mainly takes place at high-voltage peak. On the other hand, when amorphous V2O5 combined with reduced graphene oxide(rGO), it promotes the retention to 82% at a rate of 1C. Besides, through AC impedance analysis, the RC time constant model has been utilized to simulate the electrochemical reaction of equivalent circuit. Based on the result of time constant, the key point of charging/discharging stability is caused by the charge transfer resistance Rct between amorphous V2O5 and nickel foam interface.

碩士
中國文化大學
應用化學研究所
95
In this study, we calculated the doublet potential energy curves of Li atom colliding with NH free radical at the HF/CASSCF/MRCI level. The software used in this work is the MOLPRO 2K.2 quantum chemistry packages in own laboratory and the national center of high performance computing.The basis sets employed for all atoms are the cc-pVQZ basis set. We let the Li atom approach NH via different collision angles of θ=60∘﹑90∘﹑120∘and 179∘.The Point group are all Cs . The potential energy curves investigated here are the 1A', 2A’, 1A” and 2A” states. The collision energy surfaces can be constructed with these curves in the future. But in this study, we used these curves to predict the possible reaction paths, especially for the feasibility of non-adiabatic reactions. We also annalyzed the natural orbitals and main election configurations of reaction intermediates.

Power supply in any electronic system is a crucial necessity. Especially so in fully compliant personalized advanced healthcare electronic self-powered systems where we envision seamless integration of sensors and actuators with data management components in a single freeform platform to augment the quality of our healthcare, smart living and sustainable future. However, the status-quo energy storage (battery) options require packaging to protect the indwelling toxic materials against harsh physiological environment and vice versa, compromising its mechanical flexibility, conformability and wearability at the highest electrochemical performance. Therefore, clean and safe energy storage solutions for wearable and implantable electronics are needed to replace the commercially used unsafe lithium-ion batteries. This dissertation discusses a highly manufacturable integration strategy for a free-form lithium-ion battery towards a genuine mechanically compliant wearable system. We sequentially start with the optimization process for the preparation of all solid-state material comprising a ‘’Lithium-free’’ lithium-ion microbattery with a focus on thin film texture optimization of the cathode material. State of the art complementary metal oxide semiconductor technology was used for the thin film based battery. Additionally, this thesis reports successful development of a transfer-less scheme for a flexible battery with small footprint and free form factor in a high yield production process. The reliable process for the flexible lithium-ion battery achieves an enhanced energy density by three orders of magnitude compared to the available rigid ones. Interconnection and bonding procedures of the developed batteries are discussed for a reliable back end of line process flexible, stretchable and stackable modules. Special attention is paid to the advanced bonding, handling and packaging strategies of flexible batteries towards system-level applications. Finally, this work shows seamless integration of the developed battery module in an effective strategy to incorporate them into a complex architecture such as orthodontic domain in the human body. The developed optoelectronic system embedded in a 3D printed smart dental braces for enhanced enamel healthcare protection and overall healthcare cost reduction. These findings complement and provide power solution options in which flexibility of electronics is an added beneficial dimensionality to wearable biomedical and implantable devices.

No
Polymer gel electrolytes (PGE) based on polyvinylidene fluoride (PVDF), lithium salts and appropriate solvent systems, developed at Leeds University, have been shown to form tough rigid films with conductivities approaching 10¿2 S cm¿1. A continuous process has now been developed for the construction of rechargeable lithium cells by extruding the PGE as a melt and directly laminating between the anode and cathode electrodes. On cooling, the solid PGE acts as electrolyte and separator and binds the cell laminate together from within requiring no external case. This process has been successfully applied for the fabrication of cells with electrodes developed by SpectraPower Inc. in a commercial process enabling cell laminates with PGE thickness less than 0.1 mm and with energy densities approaching 170 Wh kg¿1. A prototype manufacturing facility has been set up to produce rechargeable cells of high specific capacity and high energy density. Future developments will enable rechargeable lithium ion cells to be produced on a continuous process as flat sheets opening the way for novel battery geometries.

碩士
國立清華大學
化學工程學系所
105
In the last two decades, Li-ion batteries (LIBs) has played a critically important role in the market as a primary power supplier with a higher gravimetric and volumetric capacity than other rechargeable-battery systems. However, current LIB technologies cannot satisfy the energy and power requirements of a wide range of applications, from portable electronic devices to all-electric vehicles and smart grids. In this regard, Asia Carbons and Technology INC company which locates at Taoyuan country, Taiwan (R.O.C) and Prof. Hsing-Yu Tuan Labortary have cooperated to dedicate to the progressive LIBs. Hence, the study was a cooperative work between Prof. Hsing-Yu Tuan Lab and the company. The aim was to find out the optimal conditions for assembling modified-graphite based on LIBs with high capacity, high coulombic efficiency, cycling stable. These modified samples were originally graphite materials, which has been treated under the high pressure to transform their morphologies. The sample treatment process was carried out by the company. The number of samples were 32 samples, namely G201, G202, G203 to G232 in order. In order to achieve the purpose, those modified graphite samples were initially assembled anode electrode in half-cells under the same process (described lately in chapter 2) to find out the good samples in terms of high capacity, good coulombic efficiency and cycling stable. All the produced slurries included 83,50 wt% active materials, 8.0 wt% super P and 8.5 wt% PVDF stirred in NMP solution for 1.5 hours. Then, their cycling performances were carefully compared to each other, based on the predefined goals (KPI), which resulted in obtaining four best samples. These samples were investigated further under different conditions such as (i) various coating thickness and (ii) different kinds of electrolytes to find out the best sample as well as to gain the recipe for assembling modified-graphite based on lithium-ion batteries. Besides that, those samples were analyzed via SEM images, IV test to obtain more understanding about their characteristics. It is found that the modified sample named G227 stood out as a potential candidate for anode electrode in lithium battery, since it performed stably over 50 cycles with high capacity above 320 mA h/g. Another finding was that electrolyte system which includes ethylene carbonate (EC): dimethyl carbonate (DMC): fluoroethylene carbonate (FEC) 4.5:4.5:1 (v:v) in LPF6 has enhanced the good cycling performance rather than fluoroethylene carbonate (FEC): diethyl carbonate (DEC) 3:7 (v.v) and ethylene carbonate (EC): dimethyl carbonate (DMC) 1:1 (v/v) in LPF6 system. However, this work currently facing an issue that the average capacity is quite low, which needs a lot effort to solve. In order to surpass the weakness of low capacity of modified graphite based on negative electrodes, the author continuously carried out the work named “silicon/graphite composites as anode materials” to overcome the problem. The study indicated that silicon/graphite composite has a significant improvement on specific capacity and the initial efficiency. The electrodes sustain a higher number of charge/discharge cycles with a more stable discharge capacity compared to the graphite powders only. Two full-cell coins show outstanding stability for the first 50 cycles, leading to a capacity retention of 1st sample and 2nd one are 94.68% and 92.56%, respectively. The average initial efficiency is over 86.00%. This result has exceeded the standard KPI (>85%). Besides that, the cycle performance of Si/graphite composites based-on pouch cell is also investigated. Its areal capacity and specific capacity are 3.92 mA h/cm2 and 604 mA h/g, respectively, which is much better than expected.

碩士
中國文化大學
應用化學研究所
93
Abstract In this study, we calculated the doublet potential energy curves of Li atom colliding with CH2 free radical on the HF/CASSCF/MRCI level. The software used in this work is the MOLPRO 2K.2 quantum chemistry packages in own laboratory and the national center of high performance computing. The basis sets employed for all atoms are the cc-pVQZ basis set. We let the Li atom approach CH2 via different collision angles of θ=1 ∘﹑30∘﹑60∘﹑75∘﹑90∘﹑120∘﹑140∘and 179∘.All are in the Cs symmetry. The potential energy curves investigated here are the 1A', 2A' , 1A " and 2A " states. The collision energy surfaces can be constructed with these curves in the future. But in this work, we used these curves to predict the possible reaction paths, especially for the feasibility of non-adiabatic reactions. We also annalyzed the natural orbitals and main election configurations of reaction intermediates.

碩士
國立清華大學
材料科學工程學系
103
In our work, anatase TiO2 nanostructures on Ti foil transformed from sodium titanate were synthesized by a facile hydrothermal reaction. Under different hydrothermal conditions, diverse morphologies including nanowire, nanosheet and nanobelt can be obtained. The rate of sodium ion intercalating into TiO6 structure during the hydrothermal reaction will influence the morphology of sodium titanate. High intercalation rate occurring at high temperature and high sodium ion concentration environment leads to the formation of nanowire TiO2. On the contrary, lamellar TiO2 including nanosheet and nanobelt were obtained in low intercalation rate condition. Anatase TiO2 on conductive Ti foil can be used as a binder-free anode material for lithium ion batteries. Nanowire exhibits the best lithium ion batteries performance among three different morphologies and retains 220.95 mAh/g after 100 cycles at the rate of 1 C (335 mA/g). In variable current test, at the rate of 20 C (6.7 A/g), anatase TiO2 nanowire still remains 99.04 mAh/g. The extraordinary performance can be attributed to high specific surface area and low charge transfer resistance. This result suggests that anatase TiO2 growing on Ti foil can be a promising candidate for high performance lithium ion batteries.

Indiana University-Purdue University Indianapolis (IUPUI)
The studies of rechargeable lithium-sulfur (Li-S) batteries are included in this thesis. In the first part of this thesis, a linear sweep voltammetry method to study polysulfide transport through separators is presented. Shuttle of polysulfide from the sulfur cathode to lithium metal anode in rechargeable Li-S batteries is a critical issue hindering cycling efficiency and life. Several approaches have been developed to minimize it including polysulfide-blocking separators; there is a need for measuring polysulfide transport through separators. We have developed a linear sweep voltammetry method to measure the anodic (oxidization) current of polysulfides crossed separators, which can be used as a quantitative measurement of the polysulfide transport through separators. The electrochemical oxidation of polysulfide is diffusion-controlled. The electrical charge in Coulombs produced by the oxidation of polysulfide is linearly related to the concentration of polysulfide within a certain range (≤ 0.5 M). Separators with a high porosity (large pore size) show high anodic currents, resulting in fast capacity degradation and low Coulombic efficiencies in Li-S cells. These results demonstrate this method can be used to correlate the polysulfide transport through separators with the separator structure and battery performance, therefore provide guidance for developing new separators for Li-S batteries. The second part includes a study on improving cycling performance of Li/polysulfide batteries by applying a functional polymer on carbon current collector. Significant capacity decay over cycling in Li-S batteries is a major impediment for their practical applications. Polysulfides Li2Sx (3 < x ≤ 8) formed in the cycling are soluble in liquid electrolyte, which is the main reason for capacity loss and cycling instability. Functional polymers can tune the structure and property of sulfur electrodes, hold polysulfides, and improve cycle life. We have examined a polyvinylpyrrolidone-modified carbon paper (CP-PVP) current collector in Li/polysulfide cells. PVP is soluble in the electrolyte solvent, but shows strong affinity with lithium polysulfides. The retention of polysulfides in the CP-PVP current collector is improved by ~50%, which is measured by a linear sweep voltammetry method. Without LiNO3 additive in the electrolyte, the CP-PVP current collector with 50 ug of PVP can significantly improve cycling stability with a capacity retention of > 90% over 50 cycles at C/10 rate. With LiNO3 additive in the electrolyte, the cell shows a reversible capacity of > 1000 mAh g ⁻¹ and a capacity retention of > 80% over 100 cycles at C/5 rate. The third part of this thesis is about a study on a binder-free sulfur/carbon composite electrode prepared by a sulfur sublimation method for Li-S batteries. Sulfur nanoparticles fill large pores in a carbon paper substrate and primarily has a monoclinic crystal structure. The composite electrode shows a long cycle life of over 200 cycles with a good rate performance in Li-S batteries.

Lithium iron phosphate (LiFePO4) is a promising cathode material for lithium-ion batteries. In the past few years many improvements have led to consistent cycling capabilities, even at high rates. LiFePO4 is being commercialized as a cathode material in batteries for power tools, and is a serious candidate for the future batteries of hybrid-electric or electric vehicles. It can also be commercialized for other applications requiring a low-cost and safe battery, but its low intrinsic electrical conductivity and low Li-ion diffusion are two major disadvantages. Many groups have shown that battery performance can be enhanced by addition of carbon, during synthesis or post-synthesis carbon coating through various techniques to improve electrical conductivity. Simplification or even minimization of carbon-coating methods is one area of improvement which could help to reduce cost and increase efficiency. These carbon additives can cause multiple effects on purity, crystallinity and the electrochemical performance of the final cathode material (LiFePO4) and therefore makes it difficult to optimise the quantity and specific type of carbon that needs to be added during the synthesis of LiFePO4. All synthetic procedures reported in the literature, however, show that carbon is always present in some form in the final product. In this thesis study, in order to evaluate the effect of various carbon additives unambiguously, a novel one-step co-precipitation method was developed for synthesis of carbon-free LiFePO4. A series of LiFePO4/Carbon composites were prepared where the composites were synthesised at 550, 650 and 750°C containing 5, 10 or 20 wt% carbons. Two forms of carbon additives were tested; single wall carbon nanotubes (SWCNT) and carbon black (CB). These carbons were added at one of two different stages; (1) during pre-synthesis, mixed with the LiFePO4 precursors, or (2) in post-synthesis, during the electrode preparation. This approach helped to investigate the effect that the carbon type, carbon content, mode of mixing (pre synthesis or post synthesis) and temperature have on the electrochemical performance of the active component. The topic of electron conductivity and Li-ion diffusion LiFePO4 is also very relevant, especially since this material is now touted as an important high-rate capability cathode. To investigate these effects, cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy measurements were performed. It was found that the cell discharge capacity, rate capacity and electronic conductivity of the electrode depended on the type of carbon used. The use of a 5 wt. % loading of SWCNTs as conductive additive to LiFePO4 composites prepared at 750 °C was found to improve the electrochemical performance of cells compared to cells containing CB additives. The LiFePO4 with 5 wt. % SWCNTs mixed pre-synthesis and then synthesised at 750 °C demonstrates a smaller resistance to charge-transfer (RCT = 59Ω) and good kinetic behaviour (2.9 x 10-8 cm2/s), and has the highest specific capacity (93 mAh/g and 48 mAh/g at C/20 and C/5 respectively) than any other sample except for the one with 10 wt% SWCNT. The latter demonstrates slightly improved specific capacity at C/20 (94 mAh/g) and better Li-ion kinetic behaviour (3.3 x 10-7 cm2/s) but a worse specific capacity at C/5 (46 mAh/g), probably because the charge-transfer resistance is significantly higher (RCT = 239 Ω). Therefore, the optimisation of cell performance involves optimisation of Li-ion and electron transport and the charge transfer at the electrode/electrolyte interface. Therefore, it is important to note that the material synthesised according to the novel, single-step, co-precipitation procedure described in this thesis can be applied to many other LiFePO4-carbon composite cathode materials, to compare and evaluate the effect of various carbon additives on the electrochemical performance of cathode materials.

碩士
國立臺灣科技大學
化學工程系
105
The intrinsic problems associated with the use of Li-metal anode in conventional Li-S batteries and the shuttle effect induced by the dissolution of intermediate polysulfides in the electrolyte are major concerns hindering the application of Li-S batteries. Considering the limited specific capacity of conventional Li-ion batteries (~300 mAh/g),Li2S, with theoretical capacity exceeding 1166 mAh/g, has been found great potential as cathode material in Li-S batteries. Herein, the lithium sulfide on polyacrylonitrile (Li2S-PAN) composite has been developed by three routes, namely the solid-state mixing method, solid-liquid state method, and electrochemical method. It shows that the severe or uneven reactivity in the first two routes leads to the structural damage and the shuttle effect. By contrast, Li2S-PAN composite with high structural integrity and stability can be successfully prepared by the electrochemical method. For half-cell stability testing, the first cycle specific discharge capacity reached 1233 mAh/g and the capacity retention was 87.9% after 200 cycles at 0.1 C. In addition, this research is the first one to report large-scale Li2S-PAN composite synthesized through a lithiated winding S-PAN electrode in a self-designed electrochemical cell. For Li-free-anode large-scale full-cell test, the first cycle specific discharge capacity was 600.2 mAh/g and the capacity retention was 59.4% after 50 cycles at 0.1 C. The developed electrochemical method solves the both of intrinsic problems and the prepared materials show the high stability and the excellent electrochemical performances. From a series of analysis techniques based on synchrotron radiation such as in-situ XRD, ex-situ XPS and XAS, it is found that the formation of lithium fluoride (LiF) can help to stabilize the electrochemical performance during charging/discharging and these analysis techniques demonstrate the fundamental chemical structure and the interaction between Li2S and PAN matrix. The PAN matrix involves in the electrons transfer of oxidation/reduction reaction in charging/discharging process and provides electrons to Li2S by forming the N-S covalent bond during discharge. Taking advantages of the strong N-S covalent bond, sulfur transforms directly into smaller sulfides and avoid the formation of long-chain polysulfides. Consequently, the shuttle effect is prevented and the dissolution of cathode material is effectively suppressed. The utilization of Li2S-PAN cathode material can be thus greatly enhanced.

We describe the application of alchemical free energy methods and coarse-grained models to study two key problems: (i) co-translational protein targeting and insertion to direct membrane proteins to the endoplasmic reticulum for proper localization and folding, (ii) lithium dendrite formation during recharging of lithium metal batteries. We show that conformational changes in the signal recognition particle, a central component of the protein targeting machinery, confer additional specificity during the the recognition of signal sequences. We then develop a three-dimensional coarse-grained model to study the long-timescale dynamics of membrane protein integration at the translocon and a framework for the calculation of binding free energies between the ribosome and translocon. Finally, we develop a coarse-grained model to capture the dynamics of lithium deposition and dissolution at the electrode interface with time-dependent voltages to show that pulse plating and reverse pulse plating methods can mitigate dendrite growth.

碩士
國立中正大學
化學工程研究所
106
Si materials can offer high theoretical capacities in lithium ion battery anode materials. Unfortunately, they suffer from dramatic volume expansion, resulting in the pulverization of electrode material structure during lithiation/delithiation cycles. In this work, the porous Si powders were made from rice husks by reduction with LiH. Then, the process parameters were optimized by XRD and XPS analysis. The amounts of by-products (Li4SiO4, Li2SiO3) were determined based on the XRD results. We also proposed the reaction equation of RH-SiO2 and LiH for fabrication of porous Si. The stoichiometric coefficients of the reaction equation were balanced according to the experimental data. The pure porous Si particles were characterized by BET, revealing that the average pore size was 207nm. Fluoroethylene carbonate (FEC) was added to the electrolyte to form a dense and less resistant SEI film on porous Si particles in the initial cycle of electrochemical SEI formation, which can improve the cycle performance. As a result, the porous Si anodes exhibited a high reversible capacity of 1734mAh/g at 0.5C charge rate and long cycle life (with capacity retention of 59.4% after 250 cycles). In addition, EIS analysis of the porous Si electrode was conducted. The total impedence (Rtotal) mainly consisted of the resistance of charge transfer (RCT) and the resistance of SEI film (RSEI). In the first 10 cycles, all of the impedance values decreased as the cycle number increased. However, the impedance values were slightly increased during the following 40 cycles. The porous Si/graphite composite was prepared by ball milling. The porous Si/graphite anodes exhibited a high electrochemical performance. The capacity was 669mAh/g at 0.5C with 84.5% capacity retention after 450 cycles. In the second part, the binder-free electrode material was investigated. The electrode materials contained porous Si, graphite and polyacrylonitrile (PAN). The binder and carbon black commonly used in conventional electrode was replaced with PAN. The compositions of PAN polymer after heat treatment at 550oC and 700oC was examined using XPS, Raman spectroscopy. The TGA results indicated that the weight ratio of porous silicon to nitrogen-doped carbon was 81:19 at 550oC. The electrochemical measurements showed that the porous Si/carbonized-PAN composite anodes exhibited a specific capacity of 821.5mAh/g at 0.5A/g and with 55.5% capacity retention after 100 cycles. Furthermore, the porous Si/graphite/carbonlized-PAN composite anodes exhibited a reversible capacity of 396.5mAh/g after 100 cycles at current density of 0.5A/g, and with 49.5% capacity retention. Key words：Lithium-ion battery, Porous Silicon, Rice husks, Polyacrylonitrile, Binder-free electrode

This dissertation comprehensively speaks about the state of research in Li/S electrochemical system. Li-ion batteries are all over in gadgets, laptops and almost in every portable consumer electronics. But, future energy storage demand for electrical mobility and smart grids asking for much higher energy density, sustainable and cheaper solutions. Lithium-sulfur (Li/S) technology is one of the promising solutions to such demands as it can offer five times high energy density than that of state of art Li-ion technology. Li/S system can be potentially regarded as a sustainable and cheaper technology owing to abundancy and benignity of sulfur. However, the insulating nature of sulfur and Li2S, free solubility of lithium polysulfide (LiPS) in the electrolyte, shuttling of LiPS across separator and use of metallic lithium as anode challenge the scientific community to offer some practical solutions for its commercialization . The effort can be done in various dimensions to realize stable and long-life Li/S batteries. Various startegies have been proposed to realize efficient and stable sulfur and silicon electrodes. In the end, a Li metal free Si/S full cell has been realized.

The newly emerging Stimulated Raman Scattering (SRS) Microscopy has been proved to be a powerful tool in biomedical research. This advanced imaging platform offers high spatiotemporal resolution and chemical specificity, which greatly empowers the label-free biomedical imaging and small molecule metabolite tracing. Throughout the research introduced in this thesis, we focus on the exploration of more applications of SRS microscopy beyond aforementioned. Particularly, this new expedition involves more chemistry and answered two major questions: what SRS can do for chemistry and what chemistry can do for SRS. Chapter 1 introduces the basics of SRS microscopy, such as the physical fundamentals and start-of-art instrumentations. Besides, this chapter discusses the design principles of vibrational reporters through a chemistry view. Chapter 2 introduces one of the major progresses of SRS microscopy beyond biomedical study. We use SRS microscopy to study the ion transportation and concentration polarization phenomena in lithium metal batteries (LMBs), with a strong focus in solid-state polymer electrolyte. A self-induced phase separation process over lithium metal electrode is observed and correlated with local lithium ion concentrations, which inspires a protection mechanism for durable LMB design. Chapter 3 discusses the use of SRS microscopy for in-vivo drug tracing in mammalian cells. A novel alkyne tag is incorporated into bio-engineered natural depsi-peptides and serves as Raman reporter. The mode-of-action of the labeled drug is visualized with SRS microscopy. Chapter 4 heavily focuses on the development of synthetic molecular probes for super-multiplexed optical imaging. We systematically synthesize a library of molecular probes based on 9-cyanopyronin, and their Raman features are characterized to build a model that correlates photophysical properties with structures. The Raman shifts of probes can be tuned with high precision. The multiplexing capability of the new library is demonstrated in labeling fixed and living cell samples.