Browsing by Subject "Lithium ion battery"

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Coordination complex design for applications in thin films and electrochemical energy storage
(2020-12-11) Hall, Justin Walker; Jones, Richard A., 1954-; Que, Emily; Rose, Michael; Ekerdt, John G; Campion, Alan
Several applications of d-block organometallic chemistry will be presented, spanning chemical vapor deposition precursors, lithium ion battery electrode materials, and redox flow battery electrolytes. In the first chapter, the coordination chemistry of phosphine (PH3) with Ruthenium will be explored in the context of attempts to design a carbon-free Ru(P) thin film chemical vapor deposition precursor. In the second chapter, a novel application of organometallic proton exchange to the synthesis of amorphous Li-ion battery electrodes with the goal of increased capacity retention will be demonstrated. In the third chapter, the identity and electrochemistry of the redox active species in a novel redox flow battery system will be elucidated.
Developing model architectures via atomic layer deposition to investigate interfacial electrochemical processes in lithium-ion batteries
(2015-05) Charlton, Matthew Robert; Stevenson, Keith J.; Johnston, Keith P; Mullins, C Buddie; Crooks, Richard M; Rose, Michael J
This dissertation describes the development of thin film electrodes with well-defined structures and geometries (architectures) to aid in the assessment of complex charge transfer processes in lithium ion battery systems. Titanium dioxide (TiO₂) anodes and vanadium pentoxide (V₂O₅) cathodes are synthesized via atomic layer deposition (ALD) onto transparent and opaque carbon films and used as model interfacial systems to investigate the chemical and electrochemical properties of lithium ion (Li-ion) coupled electron transfer processes at the electrode/electrolyte interface. The superior film quality and precise control over structure and chemistry afforded by ALD allow tuning of the electrode properties to facilitate coupling of analysis methods and provide new insights. A combination of analytical techniques, including cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF SIMS), and ultraviolet-visible (UV-Vis) absorption spectrophotometry, is used to elucidate mechanistic information about charge storage processes. Electrochemical investigations of TiO₂ lithiation coupled with high-resolution, spatially resolved surface analytical techniques demonstrate that in situ formation of hydrofluoric acid (HF) during cycling can alter the lithiation process and introduce partial lithiation by conversion reaction as a result of HF co-intercalation. The relationship between electrode material length scale (thickness) and the balance between charge storage via bulk intercalation versus surface pseudocapacitance is also determined for TiO₂. Combined CV and UV-Vis absorption spectrophotometry are used to investigate optical and electronic transitions in transparent V₂O₅ cathodes as a function of lithiation.
First principles study of silicon-based nanomaterials for lithium ion battery anodes
(2014-05) Chou, Chia-Yun Ph. D.; Hwang, Gyeong S.; Mullins, Charles B; Manthiram, Arunmugam; Ekerdt, John G; Stevenson, Keith
Silicon (Si)-based materials have recently emerged as a promising candidate for anodes in lithium-ion batteries because they exhibit much higher energy-storage capacities than the conventional graphite anode. However, the practical use of Si is hampered by its poor cycleability; during lithiation, Si forms alloys with Li and undergoes significant structural and volume changes, which can cause severe cracking/pulverization and consequent capacity fading arising from the loss of electrical contacts. To overcome these drawbacks, many innovative approaches have been explored with encouraging results; however, many fundamental aspects of the lithiation behavior remain ambiguous. Hence, the focus of this work is to develop a better understanding of the lithiation process at the atomistic scale using quantum mechanical calculations. In addition, based on the improved understanding, we attempt to address the fundamental mechanisms behind the successful approaches to enhance the anode performance. To lay a foundation for the investigation of alloy-type anodes, in Chapter 3, we first examine how lithiation occurs in Si and the formation of crystalline and amorphous LixSi alloys (0 ≤ x ≤ 4); followed by assessing the lithiation-induced changes in the energetics, atomic structure, electronic and mechanical properties, and Li diffusivity. The same approach is then extended to analyze the lithiation behavior of germanium (Ge) and tin (Sn) for developing a generalized understanding on the Group IV alloy-type anodes. Along this comparative study, we notice a few distinguishing features pertain only to Si (or Ge), such as the facile Li diffusion in Ge and facet-dependent lithiation in Si, which are discussed in Chapter 4. Beyond the fundamental research, we also look into factors that may contribute to the improved anode performance, including (i) finetuning of the oxidation effects in Si-rich oxides, [alpha] -SiO [subscript 1/3] (Chapter 5), (ii) maximizing the surface effects through nano-engineered structures (Chapters 6 & 7), and finally (iii) the role of interface in Si-graphene (carbon) composites (Chapter 8).
Nanostructured anode materials for Li-ion and Na-ion batteries
(2013-08) Lin, Yong-Mao; Mullins, C. B.; Heller, Adam (Professor of chemical engineering)
The demand for electrical energy storage has increased tremendously in recent years, especially in the applications of portable electronic devices, transportation and renewable energy. The performances of lithium-ion and sodium-ion batteries depend on their electrode materials. In commercial Li-ion batteries with graphite anodes the intercalation potential of lithium in graphite is close to the reversible Li/Li⁺ half-cell potential. The proximity of the potentials can result in unintended electroplating of metallic instead of intercalation of lithium in the graphite anode and frequently leads to internal shorting and overheating, which constitute unacceptable hazards, especially when the batteries are large, as they are in cars and airplanes. Moreover, graphite cannot be readily used as the anode material of Na-ion batteries, because electroplating of metallic sodium on graphite is kinetically favored over sodium intercalation in graphite. This dissertation examines safer Li-ion and Na-ion battery anode materials.
Polymers for microelectronics and energy storage
(2019-12-06) Meyer, Paul William, Ph. D.; Willson, C. G. (C. Grant), 1939-; Lynd, Nathaniel; Baiz, Carlos R; Manthiram, Arumugam; Rosales, Adrianne M
This dissertation focuses on two different applications of polymers for use in electronic devices. The first is pitch division photoresists, employed to improve the resolution of current photolithography tools. The second application employs the self-assembly of di-block copolymers for membrane applications, with specific focus given to separators in batteries. The microelectronics industry has continually devised new ways of printing smaller features to increase the complexity of devices and drive down cost. Although 193 nm exposure tools are common for printing the smallest of features, they are expensive, and many processes still use patterning at 254 and 365 nm wavelengths for patterns with less stringent length scales. To further improve the feature density for these processes, manufacturers oftentimes must purchase a new tool, requiring significant capital investment. At the core of this printing process is a photoresist, a photosensitive resin that changes solubility upon exposure to light. Pitch division photoresists improve the resolution of these exposure tools through chemistry. By employing a photobase generator in combination with a photoacid generator, the feature density obtained can be doubled without changing the aerial image, effectively extending the lifetime of exposure tools. This dissertation specifically focuses on pitch division at wavelengths at 254, 265, 355, and 365 nm. With increasing demand in portable electronics, there is also demand for improvements in energy storage, with lithium-ion batteries having taken over this landscape. Within this class of batteries, lithium metal anodes have been proposed to further increase the storage capabilities of these devices. However, lithium metal is very unstable, sometimes leading to catastrophic failure due to dendritic growth. Several types of solid electrolytes have been proposed in order to suppress lithium dendrite formation. Among them, polymer electrolytes have become an intensely studied class of materials, but generally exhibit a tradeoff between mechanical strength and ionic conductivity. The second part of the dissertation leverages the self-assembly of block copolymers into an isoporous gyroid morphology. One of the blocks is mechanically strong while the other is a selectively degradable polylactide. Because the pores created by the polylactide block can be filled with another electrolyte, the mechanical and ionically-conductive properties have been decoupled. The fabrication of these gyroid membranes and preliminary investigations into their application are presented.
Structural and electrochemical characterization of high-energy oxide cathodes for lithium ion batteries
(2012-12) Lee, Eun Sung; Manthiram, Arumugam
Lithium-ion batteries are the most promising rechargeable battery system for both vehicle applications and stationary storage of electricity produced from renewable sources such as solar and wind energies. However, the current lithium ion technology does not fully meet the requirements of these applications in terms of energy and power density. One approach to realizing a combination of high energy and power density is to use a composite cathode that consists of the high-capacity lithium-rich layered oxide Li[Li,Mn,Ni,Co]O2 and the high-voltage spinel oxide LiMn1.5Ni0.5O4. This dissertation explores the unique structural characteristics and their effect on the electrochemical performance of the layered-spinel composite oxide cathodes along with individual layered and spinel oxides over a wide voltage range (5.0 – 2.0 V). Initially, the effect of cation ordering on the electrochemical and structural characteristics of LiMn1.5Ni0.5O4 during cycling between 5.0 and 2.0 V were investigated by an analysis of the X-ray diffraction (XRD) and electrochemical data. Structural studies revealed that the cation ordering affects the size of the empty-octahedral sites in the spinel lattice. The differences in the size of the empty-octahedral sites affect the discharge profile below 3 V due to the variation in lattice distortion during lithium ion insertion into 16c octahedral sites. With the doped LiMn1.5Ni0.5-xMxO4 (M = Cr, Fe, Co, and Ga) spinels, different dopant ions have different effects on the degree of cation ordering due to the differences in ionic radii and surface-segregation characteristics. The compositional and wt.% variations of the layered and spinel phases from the nominal values in the layered-spinel composites were obtained by employing a joint XRD and neutron diffraction (ND) Rietveld refinement method. With the obtained composition and ex-situ XRD data, the mechanism for the increase in capacity and the facile phase transformation of the layered phase in the composite cathodes to a 3 V spinel-like phase during cycling was proposed. Investigations focused on synthesis temperature revealed that the electrochemical characteristics of the composites are highly affected by the synthesis temperature due to the change in the surface area of the sample and cation ordering of the spinel phase. In addition, the electrochemical performance of the lithium-rich layered oxide Li[Li,Mn,Ni,Co]O2 could be improved by blending it with a lithium-free insertion host VO2(B) and by controlling the amount of lithium ions extracted from the layered lattice during the first charge process.
Synthesis and electrochemical characterization of novel electroactive materials for lithium-ion batteries
(2017-10-02) Kreder, Karl Joseph, III; Manthiram, Arumugam; Goodenough, John B; Yu, Guihui; Hwang, Gyeong S; Ferreira, Paulo J
Lithium-ion batteries (LIBs) have become ubiquitous as energy storage devices for mobile electronics, electric vehicles, and are beginning to be used for electric grid-scale energy storage. Lithium-ion batteries offer higher efficiencies, energy density, and longer life compared to incumbent technologies such as lead-acid and nickel metal hydride. Applications in which LIBs are used are continuing to demand better performing batteries at lower cost, which requires improvement in electroactive materials. This dissertation investigates the low temperature synthesis and modification of LiCoPO₄ as a potential high-voltage and therefore higher energy density polyanion cathode material for LIBs, as well as a new class of interdigitated metal foil anodes which promises to be an inexpensive, higher energy density, alternative to graphite. Chapter 1 is a brief introduction to lithium-ion batteries and the principle of operation of intercalation type electrochemical energy storage devices. The components of lithium ion batteries are introduced, specifically the anode, cathode, separator, and electrolyte. Some of the shortfalls of the current technologies are discussed and areas of research interest are highlighted. Chapter 2 is a brief overview of the various experimental methods that are generally applicable to more than one of the subsequent chapters. Methods which are specific to a given study are discussed in their respective chapters. Chapter 3 presents work on the low temperature microwave-assisted solovthermal synthesis (MW-ST) of three unique polymorphs of LiCoPO₄, specifically the polymorphs belonging to the Pnma, Cmcm, and Pn2₁a space groups. Prior to this work, only the Pnma polymorph had been reported via MW-ST method, and electrochemistry had not yet been reported for either the Pn2₁a or Cmcm polymorph. The dependence of the polymorphs on both the water content, and ammonium hydroxide content of the solvent was shown. Although, the electrochemistry of both the Pn2₁a and Cmcm polymorphs was found to be inferior to the Pnma polymorph, the ability to synthesize phase pure materials was crucial to conducting the work presented in chapters 4 and 5. Chapter 4 presents the aliovalent substitution of V³⁺ for Co²⁺ in LiCoPO₄ via a low-temperature MW-ST process. Substitution of up to 7% vanadium for cobalt was demonstrated and verified by changes in the lattice parameters with vanadium content. Both the ionic and electronic conductivity of LiCoPO₄ was enhanced with increasing vanadium substitution, which was attributed to the introduction of both charge carriers as well as inter-tunnel cobalt vacancies. Finally, the first cycle capacity was enhanced (from 69 mAh/g to 115 mAh/g) as well as the capacity retention over cycling. Chapter 5 demonstrates a novel technique of MW-ST assisted coating of a thin (2-5nm) conformal coating of LiFePO₄ on vanadium substituted LiCoPO₄. Although the vanadium substitution was able to independently increase the performance of LiCoPO₄, the materials still suffers from severe side reactions with the electrolyte. The coating of LiFePO₄ effectively raises the Fermi energy of the cathode material above the high occupied molecular orbital (HOMO) of the electrolyte preventing side reactions and increase the coulombic efficiency to nearly 100%. Chapter 6 introduces a novel method of producing high surface area, electrically conductive, metal nanofoams via a MW-ST process. Nickel, copper, and silver metal nanofoams are made via an inexpensive yet scalable process whereby metal acetates are reduced by polyglycol under microwave irradiation. The nanofoams were characterized via BET, SEM, XRD, EDS, and TEM. The nanofoams have potential uses in many clean energy applications, particularly lithium-ion batteries. Chapter 7 introduces a new framework for making a new class of high capacity, low-cost alloying anodes for lithium ion batteries. A novel interdigitated metal foil anode (IMFA) in which a nanosized active material, such as tin, is interdigitated with an electrically conductive matrix, such as aluminum, is presented. The foils are formed by the rolling of a eutectic Al-Sn alloy into a foil, which is an extremely cheap and scalable process. The anodes demonstrate an approximately 70% increase in capacity compared to graphite over 100 cycles, at reasonably fast rates (C/5), and high coulombic efficiency (>99%). Finally, Chapter 8 gives a brief overview of the results of the prior work and proposes areas for future research.
Three dimensional computational modeling of electrochemical performance and heat generation in spirally and prismatically wound configurations
(2012-08) McCleary, David Andrew Holmes; Meyers, Jeremy P.; Ezekoye, Ofodike
This thesis details a three dimensional model for simulating the operation of two particular configurations of a lithium iron phosphate (LiFePO¬4) battery. Large-scale lithium iron phosphate batteries are becoming increasingly important in a world that demands portable energy that is high in both power and energy density, particularly for hybrid and electric vehicles. Understanding how batteries of this type operate is important for the design, optimization, and control of their performance, safety and durability. While 1D approximations may be sufficient for small scale or single cell batteries, these approximations are limited when scaled up to larger batteries, where significant three dimensional gradients might develop including lithium ion concentration, temperature, current density and voltage gradients. This model is able to account for all of these gradients in three dimensions by coupling an electrochemical model with a thermal model. This coupling shows how electrochemical performance affects temperature distribution and to a lesser extent how temperature affects electrochemical performance. This model is applicable to two battery configurations — spirally wound and prismatically wound. Results generated include temperature influences on current distribution and vice versa, an exploration of various cooling environments’ effects on performance, design optimization of current collector thickness and current collector tab placement, and an analysis of lithium plating risk.