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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
821

Combined Experimental and Numerical Study of Active Thermal Control of Battery Modules

He, Fan 16 April 2015 (has links)
Lithium ion (Li-ion) batteries have been identified as a promising solution to meet the increasing demands for alternative energy in electric vehicles (EVs) and hybrid electric vehicle (HEVs). This work describes experimental and numerical study of thermal management of battery module consisting of cylindrical Li-ion cells, with an emphasis on the use of active control to achieve optimal cooling performance with minimal parasitic power consumption. The major contribution from this work is the first experimental demonstration (based on our review of archival journal and conference literature) and the corresponding analysis of active thermal control of battery modules. The results suggest that the active control strategy, when combined with reciprocating cooling flow, can reduce the parasitic energy consumption and cooling flow amount substantially. Compared with results using passive control with unidirectional cooling flow, the parasitic energy consumption was reduced by about 80%. This contribution was achieved in three steps, which was detailed in this dissertation in chapters 2, 3, and 4, respectively. In the first step, an experimental facility and a corresponding CFD model were developed to capture the thermal behavior of multiple battery cells. Based on the experimental and CFD results, a reduced-order model (ROM) was then developed for active monitoring and control purposes. In the second step, the ROM was parameterized and an observer-based control strategy was developed to control the core temperature of battery cells. Finally, based on the experimental facility and the ROM model, the active control of a battery module was demonstrated. Each of these steps represents an important facet of the thermal management problem, and it is expected that the results and specifics documented in this dissertation lay the groundwork to facilitate further study. / Ph. D.
822

<b>Enhancing Lithium-ion Storage for Low-Temperature Battery Applications</b>

Soohwan Kim (18533676) 20 July 2024 (has links)
<p dir="ltr">This dissertation addresses the significant challenge of enhancing the performance of lithium-ion batteries (LIBs) in extremely low-temperature environments, which is critical for applications in defense and space exploration. By innovating both electrolyte formulations and electrode materials, this research extends the operational boundaries of LIBs to temperatures below -100 ℃. </p>
823

<b>THERMO-ELECTROCHEMICAL INTERACTIONS AND SAFETY ANALYTICS IN LITHIUM-ION BATTERIES</b>

Hanwei Zhou (19131412) 14 July 2024 (has links)
<p dir="ltr">Lithium-ion (Li-ion) batteries are promising electrochemical energy storage and conversion systems to drive the rechargeable world toward a sustainable future. Following the breakthrough of material innovations, advanced Li-ion batteries have significantly mitigated the range and lifetime anxieties of electric vehicles (EVs) and consumer electronics. Nevertheless, state-of-the-art Li-ion chemistries still suffer from several defects, such as rapid degradations under abusive or fast-charge scenarios and unfavorable high thermal instabilities. Essentially, aging mechanisms and safety hazards of Li-ion cells are strongly coupled events. The cell safety factors are most likely to be deteriorated as degradation progresses, making the cell less safe after a long-term deployment. In this thesis, we comprehensively investigate thermo-electrochemical interactions on the safety of Li-ion batteries. Fundamental principles of Li-ion batteries, basic knowledge about material-level thermal instabilities at electrode-electrolyte interphases, thermal characterization approaches, and thermal runaway mechanisms under abusive scenarios are fully overviewed. Thermally unstable characteristics of key cell components, including inter-electrode crosstalk as a result of oxygen liberation from cathode lattice structures, significant electric energy release from massive internal short circuit due to separator collapse, anode-centric lithium-plating-induced early exotherm, and silicon-dopant-driven thermal risks of composite anodes, are specifically discussed to understand their critical role in accelerating cell-level thermal runaway catastrophes. Aging pathways of Li-ion cells under off-normal conditions, particularly overdischarge and fast charging, are thoroughly elucidated using a promising reference electrode architecture, which effectively deconvolutes the electrode behaviors from the complex full-cell performance for precise identification of the root causes in cell failure. Given the profound revelation of degradation-safety sophistication in various Li-ion chemistries, corresponding mitigation and prevention strategies are proposed to maximize cell lifetime and reliability. This thesis provides new insights into aging and safety diagnostics of cutting-edge Li-ion batteries, taking one step further in the online monitoring of battery state of health to develop adaptive battery management systems.</p>
824

Powering Stability : Grid-Connected Batteries Influence on Peak Electricity Pricing

Holm, Emil, Shayeganfar, Parsa January 2024 (has links)
Battery Energy Storage Systems (BESSs) have become an increasingly popular feature of the electrical grid in the California ISO (CAISO) as a means to address the challenges posed by renewable energy variability and escalating peak demand. Due to their ability to reduce peak load demand on traditional generators and extend the benefits of the merit order effect, they have been theorized and claimed to reduce peak electricity prices. The purpose of this study is to test these claims within CAISO and understand what effects BESSs have had on peak electricity prices. Our findings show that there has been a significant decrease in prices after the introduction of BESSs into the grid although we found no significant effects of an increasing utilization of BESSs on peak electricity prices. We conclude that BESS utilization in CAISO has had no effect on peak electricity prices. We are contributing to the literature on the tangible market impacts of BESSs, highlighting the need for further empirical research in this domain.
825

The Green Charge : Advanced Battery Technologies for a Sustainable Future

Morantes, Gabrielle January 2024 (has links)
In order to combat the greenhouse gas emissions from the transportation sector, battery-powered electric vehicles have risen as an alternative that offers a cleaner and more sustainable mode of transportation that reduces reliance on fossil fuels and decreases carbon footprints. The climate scenario goals set by the International Energy Agency - the Net Zero Emissions, Announced Pledges, and Stated Policies Scenarios - revolve around an increased and expeditious demand for electric vehicles, machines that are intrinsically intertwined with battery production. This study focused on the sustainability of the battery's positive electrode (cathode), a critical, material-intensive component. The three different types of cathodes – Layered, Spinel, and Polyanionic – were studied to determine the basics behind their performances. It then became evident that the key ingredients of a battery cathode are lithium, manganese, nickel, iron, and aluminium. These materials were quantified in terms of their production, reserves, and resource numbers. An analysis on the electric vehicle market as a function of the type of battery chemistries was performed to determine how much the best sold and produced EV models consumed in terms of the different materials and how material intensive they were. The future production demand of the ingredients was studied. For lithium, this involved running two polynomial regressions with a demand and production peak in 2050. For manganese and nickel, the compositions of a hypothetical cathode were iterated to match the climate scenario targets, and thus, determine which compositions would meet them. Throughout the investigation, several aspects were uncovered: the current dominant battery chemistry in the EV market is the iron-rich, polyanionic type. However, to compensate for the lower performance of LFP batteries, manufacturers increased cathode size, nullifying the lithium savings. Regarding lithium production, a polynomial growth with a linear decline post the 2050 peak would seamlessly meet the climate scenario goals without exhausting the planetary resources. Manganese proved more sustainable than nickel, although nickel-rich cathodes remain the preferred choice. Manganese-rich cathodes showed the best material efficiency. Significant challenges remain in achieving sustainable EV batteries. The supply chain is highly centralized, and there are limited alternatives to lithium-reliant chemistries. Bereft from economically feasible lithium production methods, the industry is struggling to diversify its technology whilst treading lightly on fragile supply chains. There is comfort in the fact that the availability of these materials is still profuse - but this prosperity may not last if the projected demand is not congruent with the current state of nickel reserves, and if policy and car manufacturers continue to ignore the inherent chemical and physical limitations of the cathode types they prefer. In conclusion, while progress has been made, ensuring the sustainability of EV batteries requires continued innovation and strategic resource management.
826

Sustainable energy storage: The use of second life batteries in residential buildings : An investigation into the profitability of a sustainable energy storage using second life lithium-ion batteries

Blixt, Carl January 2024 (has links)
This thesis investigates the opportunities and challenges of using repurposed electric car batteries, so called Second-life Battery (SlB), in a residential building as an energy storage. The performance of SlBs is compared to a First-life Battery (FlB) by identifying two potential scenarios and using a battery degradation model. The first scenario involved the batteries providing ancillary services to the grid, while in the second scenario the batteries were used for peak shaving. The battery degradation model is based on typical usage from the scenarios. The thesis findings indicate that the SlB degrades at a slower rate than the FlB, but can perform fewer cycles. Economic performance varies based on the application and initial assumptions. Both batteries proved to be profitable in the two scenarios studied, with some of the SlB configurations outperforming FlB configurations and vice versa. The yearly compensation received, when providing ancillary services with a 1000 kWh battery, ranged between 3-8 MSEK, while the yearly compensation received, when peak shaving with a 200-300 kWh battery, ranged between 20-35 thousand SEK. The main challenges identified included reduced lifespan, security risks, potential price increases, and space constraints. On the other hand, the main opportunities identified included potential price decreases and sustainability benefits such as carbon footprint reduction and grid stability. These results may provide valuable insights for informed decision-making regarding investments in FlBs and SlBs on the Swedish market.
827

Why consumers bias? : A quantitative study about Shanghai consumer resistance intention towards remanufactured electric vehicle batteries

Li, Chenxi, Duan, Yiling January 2024 (has links)
Background: The rapid growth of electric vehicles (EVs) raises concerns about energy consumption, environmental impact, and the management of retired EV batteries (EVBs). Despite the potential benefits of remanufactured EVBs (REVBs) in resource conservation and environmental protection, and its performance parity with new batteries, consumer resistance persists. Exploring factors influencing consumer adoption and strategies for enhancing consumer acceptance is necessary to promote sustainability in the EV industry. There is little attention to consumers in remanufactured products research. Purpose: The main purpose of this study is to explore the factors that Chinese EV consumers' resist to adopt REVBs by using the innovation resistance theory and an extend factor. Methods: Quantitative research with questionnaire is used to test the model and hypotheses. Findings: The results show that Chinese consumers' willingness to adopt and use REVBs is significantly affected by risk barriers, tradition barriers, image barriers, and environmental awareness, which in turn to the formation of consumer resistance to adoption.
828

Caractérisation Multi-physique des éléments de stockage électrochimique et électrostatique dédiés aux systèmes Multi sources : Approche systémique pour la gestion dynamique d'énergie électrique / Multi-physical characterization of electrochemical and electrostatic storage elements dedicated to multi-source systems : Systemic approach for the dynamic management of electrical energy

Bellache, Kosseila 10 July 2018 (has links)
Ce travail de thèse s’inscrit dans la continuité des activités de recherche du laboratoire GREAH sur les problématiques de la gestion d’énergie électrique et de l’amélioration de la qualité énergétique des systèmes de production aux énergies renouvelables. En effet, le couplage de plusieurs sources de natures différentes entraîne des problématiques de dimensionnement, de qualité d’énergie et de la durée de vie des éléments interconnectés. La démarche scientifique repose sur la caractérisation de l'évolution des résistances et des capacités des cellules de batteries LFP/supercondensateurs en fonction des contraintes électriques et thermiques, suivi de la modélisation du vieillissement accéléré des cellules. Nous proposons dans ce mémoire de thèse des améliorations de la réponse dynamique d’un bateau fluvial à propulsion électrique par l’hybridation des batteries LFP et des supercondensateurs. Nous proposons également une approche électrothermique pour la caractérisation et la modélisation multi-physique du vieillissement des batteries et supercondensateurs en utilisant des contraintes combinées de la température et de la fréquence des ondulations du courant de charge/décharge des cellules. Les données expérimentales collectées ont permis d'établir des modèles des supercondensateurs et des batteries dédiés aux systèmes multi-sources incluant des sources d’énergie renouvelable (éoliens et hydroliens). Les modèles développés se révèlent très précis par rapport aux résultats expérimentaux. Ils permettent une bonne description du phénomène de vieillissement des batteries LFP/supercondensateurs dû aux opérations de charge/décharge avec un courant continu fluctuant combiné à une température variable. / This thesis work is a continuation of the research activities of the GREAH laboratory on the issues of the management of electrical energy and improving the energy quality of production systems for renewable energy. Indeed, the coupling of several different nature sources entails the problems of dimension, quality of energy and the lifetime of the interconnected elements. The scientific approach is based on the characterization of the evolution of the resistances and capacitances of the batteries/supercapacitors cells according to the electrical and thermal constraints, followed by the modeling of accelerated cells aging. In this thesis, we propose improvements to the dynamic response of an electric propulsion fluvial boat by using the hybrid system of lithium-batteries and supercapacitors. We also propose an electrothermal approach for the multi-physical characterization and modeling of the batteries and supercapacitors aging, using combined constraints of the temperature and frequency of the DC current ripples. The experimental data has been collected to establish models of batteries and supercapacitors dedicated to multi-source systems including renewable energy sources (wind and tidal turbines). The results of the developed models shown high accuracy compared with experimental results. These models illustrated a good description of the aging phenomenon of batteries/ supercapacitors due to charging/discharging operations with a fluctuating continuous current combined with a variable temperature.
829

Sputter Deposited Thin Film Cathodes from Powder Target for Micro Battery Applications

Rao, K Yellareswara January 2015 (has links) (PDF)
All solid state Li-ion batteries (thin film micro batteries) have become inevitable for miniaturized devices and sensors as power sources. Fabrication of electrode materials for batteries in thin film form has been carried out with the existing technologies used in semiconductor industry. In the present thesis, radio frequency (RF) sputtering has been chosen for deposition of cathode material (ceramic oxides) thin films because of several advantages such as precise thickness control and deposition of compound thin films with equivalent composition. Conventional sputtering involves fabrication of thin film using custom made pellet according to the specification of sputter gun. However several issues such as target breaking are inevitable with the pellet sputtering. To forfend the issues, powder sputtering has been implemented for the deposition of various thin film cathodes in an economically feasible approach. Optimization of various process parameters during film deposition of cathode materials LiCoO2, Li2MnO3, LiNixMnyO4, mixed oxide cathodes of LiMn2O4, LiCoO2 and TiO2 etc., have been executed successfully by the present approach to achieve optimum electrochemical performance. Thereafter the optimized process parameters would be useful for selection of cathode layers for micro battery fabrication. Chapter 1 gives a brief introduction to the Li ion and thin film solid state batteries. It also highlights the advantages of powder sputtering compared to conventional pellet sputtering. In Chapter 2, the materials used and methods employed for the fabrication of thin film electrodes and analytical characterizations have been discussed. In chapter 3, implementation of powder sputtering for the deposition of LiCoO2 thin films has been discussed. X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and electrochemical investigations have been carried out and promising results have been achieved. Charge discharge studies delivered a discharge capacity of 64 µAh µm-1 cm-2 in the first cycle in the potential range 3.0-4.2 V vs. Li/Li+. The possible causes for the moderate cycle life performance have been discussed. Systematic investigations for RF power optimization for the deposition of Li2-xMnO3-y thin films have been carried out. Galvanostatic charge discharge studies delivered a highest discharge capacity of 139 µAh µm-1cm-2 in the potential window 2.0-3.5 V. Thereafter, effect of LMO film thickness on electrochemical performance has been studied in the thickness range 70 nm to 300 nm. Films of lower thickness delivered higher discharge capacity with good cycle life than the thicker films. These details are discussed in chapter 4. In Chapter 5, fabrication and electrochemical performance of LiNixMnyO4 thin films are presented. LMO thin films have been deposited on nickel coated stainless steel substrates. The as deposited films were annealed at 500 °C in ambient conditions. Nickel diffuses in to LMO film and results in LiNixMnyO4 (LMNO) film. These films were further characterized. Electrochemical studies were conducted up to higher potential 4.4 V resulted in discharge capacities of the order of 55 µAh µm-1cm-2. In chapter 6, electrochemical investigations of mixed oxide thin films of LiCoO2 and LiMn2O4 have been carried out. Electrochemical investigations have been carried out in the potential window 2.0–4.3 V and a discharge capacity of 24 µAh µm-1cm-2 has been achieved. In continuation, TiO2 powder was added to the former composition and the deposited films were characterized for electrochemical performance. The potential window as well as the discharge capacity enhanced after TiO2 doping. Electrochemical characterization has been carried out in the potential window 1.4–4.5 V, and a discharge capacity of 135 µAh µm-1cm-2 has been achieved. Finally chapter 7 gives overall conclusions and future directions to the continuation of the work.
830

High Capacity Porous Electrode Materials of Li-ion Batteries

Penki, Tirupathi Rao January 2014 (has links) (PDF)
Lithium-ion battery is attractive for various applications because of its high energy density. The performance of Li-ion battery is influenced by several properties of the electrode materials such as particle size, surface area, ionic and electronic conductivity, etc. Porosity is another important property of the electrode material, which influences the performance. Pores can allow the electrolyte to creep inside the particles and also facilitate volume expansion/contraction arising from intercalation/deintercalation of Li+ ions. Additionally, the rate capability and cycle-life can be enhanced. The following porous electrode materials are investigated. Poorly crystalline porous -MnO2 is synthesized by hydrothermal route from a neutral aqueous solution of KMnO4 at 180 oC and the reaction time of 24 h. On heating, there is a decrease in BET surface area and also a change in morphology from nanopetals to clusters of nanorods. As prepared MnO2 delivers a high discharge specific capacity of 275 mAh g-1 at a specific current of 40 mA g-1 (C/5 rate). Lithium rich manganese oxide (Li2MnO3) is prepared by reverse microemulsion method employing Pluronic acid (P123) as a soft template. It has a well crystalline structure with a broadly distributed mesoporosity but low surface area. However, the sample gains surface area with narrowly distributed mesoporosity and also electrochemical activity after treating in 4 M H2SO4. A discharge capacity of about 160 mAh g-1 is obtained at a discharge current of 30 mA g-1. When the acid-treated sample is heated at 300 °C, the resulting porous sample with a large surface area and dual porosity provides a discharge capacity of 240 mAh g-1 at a discharge current density of 30 mA g-1. Solid solutions of Li2MnO3 and LiMO2 (M=Mn, Ni, Co, Fe and their composites) are more attractive positive electrode materials because of its high capacity >200 mAh g-1.The solid solutions are prepared by microemulsion and polymer template route, which results in porous products. All the solid solution samples exhibit high discharge capacities with high rate capability. Porous flower-like α-Fe2O3 nanostructures is synthesized by ethylene glycol mediated iron alkoxide as an intermediate and heated at different temperatures from 300 to 700 oC. The α-Fe2O3 samples possess porosity with high surface area and deliver discharge capacity values of 1063, 1168, 1183, 1152 and 968 mAh g-1 at a specific current of 50 mA g-1 when prepared at 300, 400, 500, 600 and 700 oC, respectively. Partially exfoliated and reduced graphene oxide (PE-RGO) is prepared by thermal exfoliation of graphite oxide (GO) under normal air atmosphere at 200-500 oC. Discharge capacity values of 771, 832, 1074 and 823 mAh g -1 are obtained with current density of 30 mA g-1 at 1st cycle for PE-RGO samples prepared at 200, 300, 400 and 500 oC, respectively. The electrochemical performance improves on increasing of exfoliation temperature, which is attributed to an increase in surface area. The high rate capability is attributed to porous nature of the material. Results of these studies are presented and discussed in the thesis.

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