Browsing by Subject "Battery"
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Item Design and analysis of precursors for CVD of Ru thin films and Li-ion batteries with MoP₄ anode materials(2013-08) De Pue, Lauren Joy; Jones, Richard A., 1954-The chemical vapor deposition growth of amorphous metallic alloys is currently of interest for potential uses in electronic devices. We have explored the use of ligands having Ru-H, Ru-N, and Ru-P bonds to study the effects of ligand selection. The synthesis and design of novel Ru dinuclear complexes using volatile ligands such as 3,5-bis-trifluoromethylpyrazolate and trimethylphosphine will be presented as well as materials characterization studies on grown films. Another class of functional materials of interest is the transition metal phosphides (TMPs) which have found applications in Li-ion batteries. Current research on TMPs is focused on obtaining materials with improved or new compositions and morphologies and on improving Li insertion/de-insertion reactions and charge carrying capacities. Traditional routes to these materials involve the use of high temperatures and pressures. The work presented here will focus on a synthetic route which employs relatively mild conditions. Surface analysis studies and the electrochemical performance of mesoporous MoP₄ for use as anode materials in Li-ion batteries will be described.Item A dynamic model-based estimate of the potential value of a vanadium redox flow battery for energy arbitrage and frequency regulation in Texas(2012-08) Fares, Robert Leo; Webber, Michael E., 1971-; Meyers, Jeremy P.Large-scale electrochemical energy storage is a technology that is uniquely suited to integrate intermittent renewable energy sources with the electric grid on a large scale. Grid-based energy storage also has the potential to reduce costs associated with periods of peak electric demand. For these reasons, this work describes the potential applications for grid-based energy storage, and then reviews large-scale energy storage technology innovations since the development of the lead-acid battery. The potential value of grid-based battery energy storage is discussed in the context of restructured electricity markets; then, a dynamic model-based economic optimization routine is developed to gauge the potential value of a vanadium redox flow battery (VRFB) operating for wholesale energy arbitrage and frequency regulation in Texas. Based on this analysis, the relative value of a VRFB in various regions of Texas for energy arbitrage and frequency regulation is examined. It is shown that frequency regulation is an appealing application for a grid-based VRFB, with a VRFB utilized for frequency regulation service in Texas potentially worth approximately $1500/kW. Finally, the effect of a VRFB’s characteristics on its value for frequency regulation and energy arbitrage are compared, and the operational insight developed in this work is used to glean how policies to integrate a large-scale energy storage with the electricity market might be crafted.Item Li-ion and Na-ion battery anode materials and photoanodes for photochemistry(2015-08) Dang, Hoang Xuan; Mullins, C. B.; Heller, Adam; Hwang, Gyeong S.; Fan, Donglei; Korgel, Brian A.The current Li-ion technologies allow the popularity of Li-ion batteries as electrical energy storage for both mobile and stationary applications. The graphite-based anode is most commonly used in commercial Li-ion batteries. However, because lithium intercalation in graphite occurs very close to the redox potential of Li/Li+, accidental lithium plating is a known hazard capable of resulting in internal shorting, particularly when the battery is charged rapidly, requiring higher overpotentials to accomplish the Li-intercalation. Moreover, toward the next-generation battery, a growing interest is now on promising rechargeable Na-ion batteries. The main motivation for Na-ion alternative is that sodium is much more abundant and widely distributed on the earth’s crust than lithium. In the first part of this dissertation, we investigate safer, higher specific capacity anode materials for both Li-ion and Na-ion batteries. In a separated effort toward the efficient solar energy harvesting, the second part of the dissertation examines thin film photoanodes, active in the visible-light region, for photoelectrochemical water oxidation. This part also discusses in detail the synthesis, characterization, as well as the use of co-catalysts to improve the electrode’s photochemistry performance. The current Li-ion technologies allow the popularity of Li-ion batteries as electrical energy storage for both mobile and stationary applications. The graphite-based anode is most commonly used in commercial Li-ion batteries. However, because lithium intercalation in graphite occurs very close to the redox potential of Li/Li+, accidental lithium plating is a known hazard capable of resulting in internal shorting, particularly when the battery is charged rapidly, requiring higher overpotentials to accomplish the Li-intercalation. Moreover, toward the next-generation battery, a growing interest is now on promising rechargeable Na-ion batteries. The main motivation for Na-ion alternative is that sodium is much more abundant and widely distributed on the earth’s crust than lithium. In the first part of this dissertation, we investigate safer, higher specific capacity anode materials for both Li-ion and Na-ion batteries. In a separated effort toward the efficient solar energy harvesting, the second part of the dissertation examines thin film photoanodes, active in the visible-light region, for photoelectrochemical water oxidation. This part also discusses in detail the synthesis, characterization, as well as the use of co-catalysts to improve the electrode’s photochemistry performance.Item Multiple Cell alternating current/direct current (AC/DC) Smart Battery Design(2013-05) Rosson, Thomas; Bayne, Stephen B.; Gale, Richard O.Abstract Traditional multi-cell battery packs use a fixed configuration to connect multiple individual battery cells in fixed con-figurations to achieve pre-determined voltage and current. Even with modern advances in battery chemistry and greater power density, this fixed configuration results in low reliability, low fault tolerance, and non-optimal energy conversion efficiency. This system of manufacture is hindering advances in battery performance. This paper proposes a novel scheme to manufacture batteries by individualizing cells. By changing the packaging and adding low cost circuitry, a single cell in a battery pack will be able to control its orientation with other cells in a system. The idea has potential to revolutionize the way in which battery systems are developed and controlled. By using Texas Instruments value line MSP430 microcontrollers, the cost of the system can be minimized. The use of these low cost microcontrollers makes it possible to monitor voltage and temperature levels on individual cells. Also, by utilizing the same microcontroller, the individual cell is capable of shifting individual battery cells from off state, to a positive or negative polarity. The ability to switch single cells will make it possible to create a multi-level DC output. This independent switching scheme will also make it possible to create a modified sine wave AC output. The possibilities of switching to negative polarity will double the peak-to-peak voltage of the AC waveform. The battery will also be capable of identifying and implementing only the cells that are in optimal condition. Using cells at optimal temperature and state of charge will prolong the life of each cell. A battery system that individualizes each cell into a replaceable package makes replacement of “dead cells” possible. These are the cells that currently cause traditional battery packs to be replaced. With such systems available, not only will efficiency of large multi-cell battery systems increase, but with replaceable cells the cost of ownership of a complete battery pack will decrease over the lifetime of the system.Item Operation and control strategies for battery energy storage systems to increase penetration levels of renewable generation on remote microgrids(2013-08) Such, Matthew Clayton; Masada, Glenn Y.A critical requirement of any remote microgrid is its capability to control the balance between electric generation and load within the confines of the microgrid itself. The integration of significant amounts of “as available” renewable generation to any electric grid (macro or micro) makes it more difficult to maintain this balance and can result in large frequency deviations on a microgrid. Ancillary services provide the resources required to maintain the instantaneous and ongoing balance between generation and load. Battery energy storage systems (BESS) can provide regulating reserves, a type of ancillary service, by modulating active power for frequency control, referred to as load frequency control (LFC), to reduce frequency deviations caused by sudden changes in renewable generation. Historically, the most common methodology for reducing frequency disturbances exacerbated by wind plants with BESS systems is ramp rate control and more recently lead compensation. This thesis proposed a modified lead compensator for use in microgrid applications. A PSS®E microgrid model, based upon existing validated models, was developed to test the effectiveness of the LFC controllers used to dispatch the BESS as a regulating resource to allow increased wind energy penetration levels on remote microgrids. A model of the remote microgrid of the island of Maui, Hawaii was chosen as the basis for the designs. Daily wind power data from 2012 was classified and indexed on an hourly basis by severity of variation. The worst hour for power variation from the wind plants was identified from this indexing and used as the basis for simulating the LFC controllers. The results compared the effectiveness of droop, ramp rate, lead compensation, and modified lead compensation controllers in reducing the variability in the grid frequency caused by changes in wind power generation. An RMS of variation with respect to an average over different time windows was used as the comparison metric. The combined modified lead compensator with ramp rate control showed the best performance of the overall system behavior.Item Polymorphs of lithium transition-metal phosphates : synthesis and characterization(2015-08) Assat, Gaurav; Manthiram, Arumugam; Yu, GuihuaLithium transition-metal phosphates, LiMPO₄ (M = Mn, Fe, Co, and Ni) have gained significant research interest over the past two decades as an important class of lithium-ion battery cathode materials. However, almost all of the investigations thus far have focused on the olivine polymorph which exists in orthorhombic Pnma space group. In this report, a distinct orthorhombic but non-olivine polymorph of LiMPO₄, described by a Cmcm space group symmetry, has been synthesized with M = Mn, Fe, Co, and Ni. Of these, LiMPO₄ in the Cmcm space group had never been reported before. A rapid microwave-assisted solvothermal (MW-ST) heating process with tetraethylene glycol (TEG) as the solvent and transition-metal oxalates as precursors facilitate the synthesis of these materials. The peak reaction temperatures and pressures, respectively, were below 300 °C and 30 bar, which is several orders of magnitude lower than the previously reported high pressure (GPa) method. The physiochemical and electrochemical properties of the synthesized materials are characterized with several techniques. X-ray diffraction (XRD) confirms the crystal structure with Cmcm space group and scanning electron micrographs (SEM) indicate a sub-micron thin platelet like morphology. The synthesis process conditions have been optimized to obtain impurity-free samples with correct stoichiometry, as characterized with XRD and inductively coupled plasma - optical emissions spectroscopy (ICP-OES). Upon heat treatment to higher temperatures, the transformation of the Cmcm polymorphs into olivine is observed with XRD and Fourier transform infrared spectroscopy (FTIR). Although the electrochemical activity of these polymorphs as lithium-ion cathodes turns out to be poor, the facile synthesis under mild conditions has enabled easy access to these materials, some of which were not even possible before.Item Synthesis and characterization of nanocomposite alloy anodes for lithium-ion batteries(2012-05) Applestone, Danielle Salina; Manthiram, Arumugam; Goodenough, John; Mullins, Charles; Stevenson, Keith; Meyers, JeremyLithium-ion batteries are most commonly employed as power sources for portable electronic devices. Limited capacity, high cost, and safety problems associated with the commercially used graphite anode materials are hampering the use of lithium-ion batteries in larger-scale applications such as the electric vehicle. Nanocomposite alloys have shown promise as new anode materials because of their better safety due to higher operating potential, increased energy density, low cost, and straightforward synthesis as compared to graphite. The purpose of this dissertation is to investigate and understand the electrochemical properties of several types of nanocomposite alloys and to assess their viability as replacement anode materials for lithium-ion batteries. Tin and antimony are two elements that are active toward lithium. Accordingly, this dissertation is focused on tin-based and antimony-based nanocomposite alloy materials. Tin and antimony each have larger theoretical capacities than commercially available anodes, but the capacity fades dramatically in the first few cycles when metallic tin or antimony is used as the anode in a lithium-ion battery. This capacity fade is largely due to the agglomeration of particles in the anode material and the formation of a barrier layer between the surface of the anode and the electrolyte. In order to suppress agglomeration, the active anode material can be constrained by an inactive matrix of material that makes up the nanocomposite. By controlling the surface of the particles in the nanocomposite via methods such as the addition of additives to the electrolyte, the detrimental effects of the solid-electrolyte interphase layer (SEI) can be minimized, and the capacity of the material can be maintained. Moreover, the nanocomposite alloys described in this dissertation can be used above the voltage where lithium plating occurs, thereby enhancing the safety of lithium-ion batteries. The alloy anodes in this study are synthesized by high-energy mechanical milling and furnace heating. The materials are characterized by X-ray diffraction, scanning and transmission electron microscopies, and X-ray photoelectron spectroscopy. Electrochemical performances are assessed at various temperatures, potential ranges, and charge rates. The lithiation/delithiation reaction mechanisms for these nanocomposite materials are explored with ex-situ X-ray diffraction. Specifically, three different nanocomposite alloy anode materials have been developed: Mo3Sb7-C, Cu2Sb-Al2O3-C, and Cu6Sn5-TiC-C. Mo3Sb7-C has high gravimetric capacity and involves a reaction mechanism whereby crystalline Mo3Sb7 disappears and is reformed during each cycle. Cu2Sb-Al2O3-C with small particles (2 - 10 nm) of Cu2Sb dispersed in the Al2O3-C matrix is made by a single-step ball milling process. It exhibits long cycle life (+ 500 cycles), and the reversibility of the reaction of Cu2Sb-Al2O3-C with lithium is improved when longer milling times are used for synthesis. The reaction mechanism for Cu2Sb-Al2O3-C appears to be dependent upon the size of the crystalline Cu2Sb particles. The coulombic efficiency of Cu2Sb-Al2O3-C is improved through the addition of 2 % vinylethylene carbonate to the electrolyte. With a high tap density of 2.2 g/cm3, Cu6Sn5-TiC-C exhibits high volumetric capacity. The reversibility of the reaction of Cu6Sn5-TiC-C with lithium is improved when the material is cycled above 0.2 V vs. Li/Li+.