Self-healing Polymers for Lithium Metal Batteries

L'abstract è presente nell'allegato / the abstract is in the attachmen

Ligno cellulosic materials for energy storage

The constantly increasing production of a large variety of portable consumer electronic devices and the urgent request of replacement of polluting, internal combustion cars with more efficient, controlled emissions vehicles, such as hybrid or electric vehicles require the development of new reliable and safe power sources. Furthermore the continuous decrease of the oil resources and the growing concern on the climate changes call for a larger use of green, alternative energy sources, such as solar and wind. But wind does not blow on command and the sun does not always shine thus, this discontinuity in operation leads to the need of suitable storage systems to efficiently run renewable energy plants. It is evident that a new energy economy has to emerge, and it must be based on a cheap and sustainable energy supply. Lithium ion batteries, due to their high-energy efficiency, appear as ideal candidates. Although these batteries are well established commercial products, further research and development is required to improve their performance to meet the market requirements. In particular, enhancement in safety, cost, and energy density are needed. A big portion of the R&D studies are nowadays devoted to the search for optimal materials both for the electrodes and the electrolyte of the battery: as far as the electrolyte is concerned, the main goal is to replace the liquid electrolyte with a solid one. The passage to a solid configuration gives concrete promise of increasing cell safety and reliability and, at the same time, of offering modularity in design and ease of handling. Behind the optimization of existing batteries a big effort in this field is the transformation of current batteries into a light, flexible, portable device. If integrated structures containing the three essential components (electrodes, spacer, and electrolyte) of the electrochemical cells can be made mechanically flexible, it would enable these to be embedded into various functional devices in a wide range of innovative products such as smart cards, displays, and implantable medical devices. In the fabrication of such a device the exploitation of cellulose as a flexible material and at the same time the exploitation of the papermaking and printing techniques for the development of paper electrodes and electrolytes and, in a future, of the full paper battery, is under consideration. This will also open the way to a reinvestment of the paper technologies in a high tech field such as the Lithium based batteries. Paper industry, as a matter of fact, is in Europe an important manufacturing industry but the economic change together with the development of electronics highly threaten the role and the surviving of such an activity. In this context grows the urgent need for higher value-added paper products and the conversion of the traditional paper industry. Introducing paper into new products with more profitable markets is crucial. The research work of the present thesis has been developed in collaboration with the “Centre Technique du Papier “(CTP) in Grenoble (Fr). The work has been focused on the use of cellulose in the form of handsheet or microfibrils for the production of innovative electrolyte membranes to be used in Li-based batteries. Two research lines have been followed: 1- Development of composite membranes based on cellulose microfibrils and a polymeric matrix obtained by photopolymerisation of reactive oligomers. 2- Development of multilayered membranes made of cellulose handsheet and polymeric layers obtained by photopolymerisation of reactive oligomers. Both the research lines adopt the photopolymerisation process for developing the membranes. In particular using multifunctional monomers, highly cross-linked polymer membranes are obtained which can be successfully used as gel or solid polymer electrolytes. The process is fast, low cost and versatile. In fact a fully cured polymer is obtained in seconds at room temperature irradiating a proper mixture of reactive molecules and photoinitiator

Applications of the novel bio-derived solvent Cyrene™ in polymer chemistry

Polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N’-dimethylformamide and N,N’-dimethylacetamide are under regulatory pressure worldwide due to their toxicity. Cyrene™, a bio-based solvent first developed by the University of York in collaboration with Circa Group made from cellulosic biomass, represents a promising alternative to polar aprotic solvents with chronic toxicity or other health-related concerns. This thesis explores the use of Cyrene as polar aprotic solvents replacement in polymer dissolution for graffiti removal, extractions of flavonoids, dispersion of carbon nanotubes, polymerisation and/or production of poly(amide-imide) wire enamels and production of filtration membranes. Cyrene proved a good cleaning agent for acrylic and cellulose-based graffiti aerosols, giving comparable results to N-methyl-2-pyrrolidone, without the latter’s chronic toxicity and chemical contamination concerns. Poly(amide-imide) enamels synthesised with Cyrene were chemical resistant, showed superior adhesion strength and were flexible. Cyrene showed up to ten times better extraction capacity of flavonoids (hesperidin and rutin) when mixed with water than using established ethanol-water mixtures and an increase to 91% when heated up to 65 °C. Cyrene demonstrated an efficient liquid media to disperse carbon nanotubes and reached concentrations up to 0.27 mg mL-1, which were stable for up to six months. Cyrene produced membranes tailored for applications from reverse osmosis (˂0.001 µm pore size) to microfiltration (0.1-10 µm) by changing polymers employed and the viscosity of the casting solution. Cyrene-based membranes showed higher porosity than usual and formed pores without the use of additives. Hansen Solubility Parameters were employed in this work to predict polymer dissolutions and discover new viable blends of Cyrene with other green solvents for these applications. This study has demonstrated the applicability of Cyrene across a broad range of applications involving polymer synthesis and fabrication of advanced materials, especially those which do not require rapid evaporation of the solvent or where higher viscosity is essential

Advances, challenges, and environmental impacts in metal-air battery electrolytes

Efficient energy storage technologies are vital in the current efforts towards decarbonisation. Batteries, as one of the most versatile electrochemical energy storage systems, have the potential to shape the transition from the current climate crisis scenario to a carbon neutral and sustainable future. In particular, metal-air batteries are gaining scientific and industrial interest as promising contenders to the ubiquitous lithium-ion batteries. The electrolyte plays a critical role in metal-air batteries as it determines the battery performance, its safety and the operating lifespan. The low-density, ease of processing, good thermal and electrochemical stability, mechanically stiff but ductile character, electrically insulating properties and tailor-made chemistry make polymers singularly interesting to be applied as a separator/liquid electrolyte pair, gel-electrolytes or solid-electrolytes. Accordingly, in this work the current bottlenecks and challenges in metal-air batteries are presented, with particular emphasis on the electrolyte design. The implementation of aqueous liquid electrolytes, organic liquid electrolytes, polymer membranes soaked in liquid electrolytes, gel-like electrolytes and solid-state electrolytes is discussed and the environmental impacts associated with metal-air batteries are analysed within a Circular Economy perspective. We expect this work can guide future efforts in the development of potentially sustainable next generation metal-air batteries

Organic solar cells: life cycle assessment as a research tool to reduce payback time and environmental impacts

Mención Europeo / Mención Internacional: Concedido[SPA] Las sociedades modernas están llamadas a repensar y rediseñar el modelo energético a otro más sostenible si se quiere conservar el equilibrio ecológico. Las energías renovables como tecnologías de bajas emisiones pueden hacer frente a los objetivos del cambio climático. La luz del sol, en particular es una posible solución como recurso abundante y distribuido que es. De entre las tecnologías fotovoltaicas existentes, una nueva generación, la fotovoltaica orgánica (OPV) se ha desarrollado de manera exponencial en los últimos cinco años, mostrando un gran potencial. Estos dispositivos están compuestos de materiales poliméricos semiconductores, depositados sobre sustratos flexibles. A pesar de que siguen siendo grandes los retos a superar, hay una investigación activa en el campo la física de materiales tema que ha permitido, por ejemplo, que la eficiencia de los dispositivos se haya multiplicado por diez durante la última década. Estos avances llevan a esperar que aparezcan métodos de producción rápida, baratos y de bajo impacto sobre el medio ambiente. En esta tesis, se han preparado dispositivos fotovoltaicos orgánicos en dos escalas: a nivel de laboratorio, y mediante métodos de producción masiva o roll-to-roll. El gran potencial que ésta tecnología puede ofrecer se ha cuantificado a través de análisis de ciclo de vida (LCA). Estos estudios han tratado de establecer los parámetros que son fundamentales en la fabricación de éstos dispositivos a escala semi industrial y cuantificar el potencial de la tecnología de células solares de polímeros. Los resultados de la aplicación de ésta metodología a la producción de impresos módulos poliméricos a escala semi industrial, mediante varias rutas han sido prometedores.[ENG] In view of the world energy panorama, modern societies are urged to rethink and redesign the energy model into a more sustainable one if they want to preserve an ecological balance. Renewable energies as low-carbon technologies can tackle climate change targets. Sunlight in particular, as the most abundant resource and sustainable resource, is a possible solution. Among the existing photovoltaic technologies, organic photovoltaics (OPV) has evolved in an exponential way in the last five years exhibiting a large potential. Despite that there are still important challenges to overcome, there is an active research in this subject that has enabled for example that the efficiency of the devices has increased by a factor of 10 during the last decade. These progress lead to expect fast, cheap and low environmental impact production methods. In this thesis, OPV devices have been prepared by different methods and the great potential of this technology has been quantified through life cycle assessment (LCA) methods. LCA studies on production of printed polymeric modules at semi industrial scale have been carried out, showing promising results. The studies have sought to establish the parameters that are critical for the beneficial use of polymer solar cells in society and to firmly demonstrate where the potential of the polymer solar cell technology is.Universidad Politécnica de CartagenaPrograma de doctorado en Energías Renovable

Solid Electrolytes Derived From Precursors and Liquid-Feed Flame Spray Pyrolysis Nano-Powders to Enable the Assembly of All-Solid-State-Batteries

Solid electrolytes enable several next-generation energy storage systems (designs) including solid oxide fuel cells, super capacitors, and batteries. State-of-the-art battery technologies depend highly on the discovery of electrically insulating solids with high ionic mobilities. Current Li-ion batteries (LIBs), using traditional organic liquid electrolytes, suffer from poor electrochemical and thermal stabilities, leakage and flammability. Hence, replacing liquids with solid electrolytes offers multiple possibilities for developing new battery chemistries and designs. Solid electrolytes enhanced thermal stabilities provide opportunities to design new architectures that simplify battery configurations and reduce the peripheral mass of traditional LIBs. For example, the battery pack can be redesigned to minimize thermal management systems and overpressure vents are typically installed to overcome the challenges of using flammable liquid electrolytes. Furthermore, solid electrolytes facilitate adoption of newer battery chemistries. The development of state-of-the-art Li-S and Li-air batteries will benefit greatly from the use of solid electrolytes. In this dissertation, we investigate the design, synthesis, characterization, and performance of polymer and inorganic solid electrolytes to enable the assembly of all-solid-state batteries (ASSBs). Key properties that determine the utility of solid electrolyte include high ionic conductivity (>10-6 S/cm), high transference number (≈ 1), low electrical conductivity (>10-8 S/cm), wide electrochemical stability window (0-5 V vs Li/Li+), good chemical and thermal stability, excellent mechanical properties, low cost, ease of fabrication, eco-friendliness, and simple device integration. Our first study is to develop polymer precursor electrolytes that offer properties anticipated to be similar or superior to (lithium phosphorous oxynitride, LiPON) glasses. Such precursors offer the potential to be used to process LiPON-like thin glass/ceramic coatings for use in ASSBs. LiPON glasses provide a design basis for the synthesis of sets of oligomers/polymers by lithiation of OP(NH2)3-x(NH)x [from OP(NH)3], OP(NH2)3-x(NHSiMe3)x and [P=N]3(NHSiMe3)6-x(NH)x. Treatment with selected amounts of LiNH2 provides varying degrees of lithiation and Li+ conducting properties commensurate with Li+ content. Polymer electrolytes impregnated in/on Celgard exhibit Li+ conductivities up to ~1×10-5 S cm-1 at room temperature and are thermally stable to ≈150 °C. A Li-S battery assembled using a Li6SiPON composition polymer electrolyte exhibits an initial reversible capacity of 1500 mAh gsulfur-1 and excellent cycle performance at 0.25 and 0.5 C rate over 120 cycles at room temperature. We then show the versality of co-dissolution of poly(ethylene oxide) (PEO, Mn 900k) with LixPON and LixSiPON polymer systems at ratios of approximately 3:2 followed by casting provides transparent, solid solution films 25-50 µm thick, lowering PEO crystallinity, and providing measured impedance values of 0.1-2.8 mS/cm at ambient. These values are much higher than simple PEO/Li+ salt systems. These solid solution polymer electrolytes (PEs) are: (1) thermally stable to 100 °C; (2) offer activation energies of 0.2-0.5 eV; (3) suppress dendrite formation and (4) enable the use of lithium anodes at current densities as high as 3.5 mAh/cm2. Galvanostatic charge/discharge cycling of SPAN/PEs/Li cell (SPAN = sulfurized, carbonized polyacrylonitrile) shows discharge capacities of 1000 mAh/gsulfur at 0.25 C and 800 mAh/gsulfur at 1 C with high columbic efficiency over 100 cycles.PHDMaterials Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168123/1/elenite_1.pd

Oxygen Reduction and Evolution Reactions in Alkaline and Non-aqueous Electrolytes for Li-Air Batteries : RRDE and DEMS Investigations

Due to the worldwide growing energy demand and depletion of fossil fuel resources, sustainable renewable energy conversion and storage systems have to be developed. Among the promising possibilities are the rechargeable batteries. Li-air batteries could be a key technology for automotive applications because of their higher (3-5 times) theoretical capacity than the state-of-the-art Li-ion batteries. However, this technology is facing some critical challenges such as the poor efficiency, high overpotential and electrolyte instability. The current research focuses on two types of Li-Air batteries, namely, aprotic and aqueous electrolyte batteries. Despite the intensive work in the last decade, the fundamental electrochemical reactions such as oxygen reduction reaction (ORR) and oxygen evolution (OER) in aprotic electrolytes are not well understood. Since with aprotic electrolytes the formation of a blocking film of the discharge products limits the capacity, an aqueous Li-air battery is an alternative scenario. In this work, two main issues are addressed: i) development of an efficient carbon-free bifunctional catalyst for the air electrode in alkaline media. ii) mechanistic, kinetic and quantitative investigations of ORR/OER in aprotic electrolytes. After an introduction to the topic, a theoretical background followed by a description of the experimental methods is presented. Subsequently, the results and discussion section consists of 6 chapters. The thesis is then closed with the summary and future perspectives. The results and discussion section starts with chapter 4 (already published, Electrochimica Acta 2015, 151, 332) on the investigation of an efficient bifunctional catalyst based on Ag+Co3O4 for ORR/OER in alkaline media. Interestingly, the combination of both components in one mixture showed superior activity than its single components along with good stability. Ag+Co3O4 mixed catalyst containing 10-20 wt% of Co3O4 is the optimum composition. Rotating ring-disc electrode (RRDE) method revealed negligible formation of peroxide intermediate. Oxygen evolution is also monitored using differential electrochemical mass spectrometry (DEMS). To understand the origin of such synergistic effect between Ag and Co3O4, surface and XPS analyses were conducted (Chapter 5). Further investigations on the activity of Ag+ perovskite catalyst and the role of the support (Ni vs. Ag) are presented in chapter 6. In chapter 7, to better understand the mechanism of OER on Co3O4 and the mixed catalyst, DEMS experiments together with isotope labeling are presented. An oxygen exchange process in the lattice oxygen is inferred. In this part, a new small-volume electrolyte DEMS cell design is developed for application of massive electrodes. The last two chapters are devoted to measurements in aprotic electrolytes for Li-O2 system. RRDE and DEMS were used to characterize the reactions in Tetraglyme G4, DMSO and their mixture. The significant role of the solvent properties (e.g. donor number) on the mechanism is assessed (chapter 8). DEMS enabled us not only to detect the main products and by-products but also the number of electrons transferred per oxygen molecule during discharge and charge. The results showed reversible formation of Li2O2 as the main discharge product despite of the side reactions. The catalytic activity of Co3O4 catalyst in DMSO is reported. In chapter 9, a novel electrolyte based on 1,3-dimethylimidazolidinone solvent is investigated for the first time for Li-O2 battery. Although further research has to be done, this better understanding of the processes could help in the development of strategies for the realization of such Li-air batteries.Sauerstoffreduktion und -entwicklung in alkalischen und nichtwässrigen Elektrolyten für Li-Luft-Batterien : RRDE und DEMS Untersuchungen Aufgrund des weltweit wachsenden Energiebedarfs und der Erschöpfung fossiler Brennstoffe müssen nachhaltige, erneuerbare Energienumwandlungs- und Speichersysteme entwickelt werden. Hierfür stellen wiederaufladbare Batterien vielversprechende Möglichkeiten dar. Insbesondere Li-Luft-Batterien könnten eine Schlüsseltechnologie für Automobilanwendungen sein, weil sie höhere (3-5 mal) theoretische Kapazitäten im Vergleich zu herkömmlichen Li-Ionen-Batterien haben. Diese Technologie steht jedoch vor einigen kritischen Herausforderungen wie schlechte Wiederaufladbarkeit, hohe Überspannung und Elektrolytinstabilität. Die aktuelle Forschung konzentriert sich auf zwei Arten von Li-Luft-Batterien, nämlich aprotische und wässrige Elektrolyt-Batterien. Trotz der intensiven Arbeit im letzten Jahrzehnt sind die grundlegenden elektrochemischen Reaktionen wie Sauerstoffreduktion (ORR) und -entwicklung (OER) in aprotischen Elektrolyten nicht gut verstanden. Da bei aprotischen Elektrolyten die Entladungsprodukte der ORR die Elektrode blockieren und dadurch die Kapazität der Batterie begrenzen, stellen Li-Luft-Batterien mit wässrigen Elektrolyt eine Alternative dar. Die vorliegende Arbeit befasst sich mit zwei Hauptthemen: i) Entwicklung eines effizienten, kohlenstofffreien bifunktionellen Katalysators für die Luftelektrode in alkalischen Elektrolyten. ii) Mechanistische, kinetische und quantitative Untersuchungen von ORR/OER in aprotischen Elektrolyten. Nach einer Einführung in das Thema folgen die theoretische Grundlagen mit einer Beschreibung der experimentellen Methoden. Anschließend werden die Ergebnisse und die Diskussion in 6 Kapiteln dargestellt. Die Arbeit endet mit einer Zusammenfassung und einem Ausblick. Die Ergebnisse und Diskussion beginnen mit Kapitel 4 (schon veröffentlicht, Electrochimica Acta 2015, 151, 332) zur Untersuchung eines effizienten bifunktionellen Katalysators auf der Basis von Ag + Co3O4 für ORR/OER in alkalischen Elektrolyten. Interessanterweise zeigte eine Kombination von beiden Komponenten eine höhere Aktivität als die einzelnen Komponenten und darüber hinaus eine gute Stabilität. Ag + Co3O4-Mischkatalysator, der 10-20 Gew.% Co3O4 enthielt, zeigte die optimale Aktivität. Die rotierende Ringscheibenelektrode (RRDE) zeigte eine vernachlässigbare Bildung des Peroxid-Intermediates. Die Sauerstoffentwicklung wurde mittels differentieller elektrochemischer Massenspektrometrie (DEMS) nachgewiesen. In Kapitel 5 werden Oberflächen- und XPS-Analysen gezeigt, um den Ursprung eines solchen synergistischen Effekts zwischen Ag und Co3O4 zu verstehen. Weitere Untersuchungen über die Aktivität des Ag+Perowskit-Katalysators und die Rolle des Trägers (Ni und Ag) sind in Kapitel 6 dargestellt. Zum besseren Verständnis des Mechanismus der OER auf Co3O4 und Mischkatalysatoren wurden DEMS-Messungen zusammen mit Isotopenmarkierung durchgeführt und der Austausch des Gittersauerstoffs nachgewiesen. Hierfür wurde eine DEMS-Zelle mit kleinem Elektrolytvolumen für die Verwendung von massiven Elektroden entwickelt. Die letzten beiden Kapitel widmen sich Messungen in aprotischen Elektrolyten für das Li-O2-System. RRDE und DEMS wurden verwendet, um die Reaktionen in Tetraglyme G4, DMSO und deren Gemische zu charakterisieren. Die signifikante Rolle der Lösungsmitteleigenschaften (z.B. Donorzahl) auf den Mechanismus wird in Kapitel 8 evaluiert. DEMS ermöglichte es uns, nicht nur die Hauptprodukte und Nebenprodukte zu detektieren, sondern auch die Anzahl der übertragenen Elektronen pro Sauerstoffmolekül während der Entladung und Ladung. Die reversible Bildung von Li2O2 als Hauptentladungspruduct wurde trotz der Nebenreaktionen nachgewiesen. Die katalytische Aktivität des Co3O4 Katalysators in DMSO wird gleichfalls beschrieben. In Kapitel 9 wird ein neuartiger Elektrolyt auf Basis von 1,3-Dimethylimidazolidinon-Lösungsmittel erstmals für Li-O2-Batterien untersucht. Obgleich weitere Forschungen durchgeführt werden müssen, könnte das bessere Verständnis der Prozesse bei der Entwicklung von Strategien für die Realisierung solcher Li-Luft-Batterien helfen

Advance in Composite Gels

In the last few decades, various composite gels have been developed. In recent years, further advances have been made in the development of novel composite gels with potential applications in various fields. This reprint offers the latest findings of composite gels by experts throughout the world

Acoustic cavitation characterisation in viscous deep eutectic solvents for optimisation of sonoprocessing of technology critical materials

The UK alone produced a total of 1.6 Mt of electronic waste in 2019, containing approximately 380,000 kg of technology critical metals worth $148 M per annum. Within this, printed circuit boards (PCBs) are the largest source of metals from electronic waste, containing up to 30-40 wt.% of technology critical metals. Traditional recycling techniques lack selectivity and have significant environmental and health impact. Ionometallurgy is a promising new technique for recovering metals from electronic waste using deep eutectic solvents (DESs). These solvents offer distinct advantage over traditional techniques, including much lower temperature requirements, avoidance of toxic reagents and reduced water consumption. DESs are cheap, readily available and can be adapted for selectivity. Despite these advantages, DESs are limited by slow dissolution kinetics primarily due to slow mass transport associated with their high viscosities. Power ultrasonics presents a useful solution to these issues. Sonication in DES is hypothesised to increase mass transport, remove passivating surface layers and promote cavitation-mediated effects. However, study into the cavitation activity in solutions other than water are limited. For efficient processing, cavitation generated at the tip of a sonotrode as a function of input power is required. This work is the first comprehensive investigation of cavitation in DESs, for process optimisation to enhance precious metal recycling. Detailed characterisation of the cavitation generated by two sonotrodes in a number of DESs of varying viscosity and water is performed. High-speed imaging (HSI) and acoustic detection from a novel in-house constructed cavitation detector, characterised and validated against a commercially available cavitation sensor (NPL CaviSensorTM), identifies potentially optimal sonication parameters in each liquid. Detailed characterisation of each DES combining synchronised acoustic detection and HSI reveals generation of specific cavitation dynamics and associated cavitation structure, often characterised by a densely packed bulbous cavitation cloud, generating multi-fronted shockwaves. The sonotrode is deployed in DES for the delamination of technology critical metals from waste PCBs. Sonication was observed to delaminate the metals from the PCB at a rate over thirty times faster than in silent conditions. Furthermore, an optimally identified lower power sonication was shown to delaminate a greater quantity of metals from the PCB compared to a higher power sonication, over the same duration. The sonotrode is also deployed to investigate delamination of alternative technology critical resources; lithium-ion batteries and photovoltaics, as well as for rate enhancement of electrodissolution of copper. Further collaborative studies investigate single-bubble dynamics for validation of modelling in the audible frequency range, with interesting potential applications. The results of the studies in this thesis demonstrate the utility and validity of proper cavitation characterisation in solutions intended for sonoprocessing. This characterisation can be performed simply, using bespoke, cheap passive cavitation detectors to gather acoustic measurements at sufficiently fine incremental input powers. Identification of optimal powers of any ultrasonic system for maximum cavitation efficiency is of relevance to many potential processes. In particular, the need for green technologies for electronic waste recycling, could present an ideal problem that can be tackled by ultrasonically enhanced ionometallurgy