Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Rhode Island, 2006. / Includes bibliographical references (leaves 99-105).

Investigations of the lithium/molybdenum disulfide intercalation battery showed that naturally occurring molybdenite, MoS₂, from the Endako mines had a type of capacity not found in synthetic MoS₂. The behaviour of this extra capacity was examined and attempts were made to find its source. Materials were synthesized that could indirectly produce the same electrochemical behaviour, and in-situ X-ray diffraction determined MO₃S₄ to be the crystal responsible for this capacity. The lithium/Mo₃Si, system was found to be an intercalation battery with an energy density of about 275 watt-hours per kilogram of cathode material. Over half of the capacity was at 2.09V in a first order phase transition which did not greatly alter the host lattice. Most of the remaining capacity was divided evenly between regions of continuous lattice expansion near 2.46V and 2.05V. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The growing technological application of metallic lithium has produced a greater need to understand its fundamental surface chemical properties. The use of lithium as an anode in high-energy density battery systems represents one application where this knowledge is required to optimize system performance. The surface chemistry of lithium will be discussed in terms of oxidants which represent the reductive half-cell components of these batteries, contaminants present during cell fabrication, and solvents used as the electrolytic medium. These systems have been studied in the low pressure limit ( < 1 millitorr) at atomically clean lithium surfaces using X-ray Photoelectron Spectroscopy (XPS). The lithium/sulfur dioxide system has been singled out for detailed study in order to explore the relationship between gas-phase and solution-phase processes. Electrochemical characterization of the lithium anode has been conducted as a function of controlled surface composition within this system. The ability of lithium to induce corrosion at structural components of these batteries (i.e., glass insulators) has also been investigated. A description of the chemical activity of lithium and its consequence has been developed from these results.

Lithium ion batteries have revolutionized the portable electronics market since their commercialization first by Sony Corporation in 1990. They are also being intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO₂ cathode. However, only 50% of the theoretical capacity of LiCoO₂ can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. These drawbacks together with the high cost and toxicity of Co have created enormous interest in alternative cathodes. In this regard, spinel LiMn₂O₄ has been investigated widely as Mn is inexpensive and environmentally benign. However, LiMn₂O₄ exhibits severe capacity fade on cycling, particularly at elevated temperatures. With an aim to overcome the capacity fading problems, several cationic substitutions to give LiMn[subscript 2-y]M[subscript y]O₄ (M = Cr, Fe, Co, Ni, and Cu) have been pursued in the literature. Among the cation-substituted systems, LiMn[subscript 1.5]Ni[subscript 0.5]O₄ has become attractive as it shows a high capacity of ~ 130 mAh/g (theoretical capacity: 147 mAh/g) at around 4.7 V. With an aim to improve the electrochemical performance of the 5 V LiMn[subscript 1.5]Ni[subscript 0.5]O₄ spinel oxide, various cation-substituted LiMn[subscript 1.5-y]Ni[subscript 0.5-z]M[subscript y+z]O₄ (M = Li, Mg, Fe, Co, and Zn) spinel oxides have been investigated by chemical lithium extraction. The cation-substituted LiMn[subscript 1.5-y]Ni[subscript 0.5-z]M[subscript y+z]O₄ spinel oxides exhibit better cyclability and rate capability in the 5 V region compared to the unsubstituted LiMn[subscript 1.5]Ni[subscript 0.5]O₄ cathodes although the degree of manganese dissolution does not vary significantly. The better electrochemical properties of LiMn[subscript 1.5-y]Ni]subscript 0.5-z]M[subscript y+z]O₄ are found to be due to a smaller lattice parameter difference among the three cubic phases formed during the chargedischarge process. In addition, while the spinel Li[subscript 1-x]Mn[subscript 1.58]Ni[subscript 0.42]O₄ was chemically stable, the spinel Li[subscript 1-x]Co₂O₄ was found to exhibit both proton insertion and oxygen loss at deep lithium extraction due to the chemical instability arising from a overlap of the Co[superscript 3+/4+]:3d band on the top of the O[superscript 2-]:2p band. The irreversible oxygen loss during the first charge and the consequent reversible capacities of the solid solutions between Li[Li[subscript 1/3]Mn[subscript 2/3]]O₂ and Li[Co[subscript 1-y]Ni[subscript y]]O₂ has been found to be determined by the amount of lithium in the transition metal layer of the O3 type layered structure. The lithium content in the transition metal layer is, however, sensitively influenced by the tendency of Ni[superscript 3+] to get reduced to Ni[superscript 2+] and the consequent volatilization of lithium during synthesis. Moreover, high Mn4+ content causes a decrease in oxygen mobility and loss. In addition, the chemically delithiated samples were found to adopt either the parent O3 type structure or the new P3 or O1 type structures depending upon the composition and synthesis temperature of the parent samples and the proton content inserted into the delithiated sample. In essence, the chemical and structural stabilities and the electrochemical performance factors of the layered (1-z) Li[Li[subscript 1/3]Mn[subscript 2/3]]O₂ · (z) Li[Co[subscript 1-y]Ni[subscript y]]O₂ solid solution cathodes are found to be maximized by optimizing the contents of the various ions. / text

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2007. / Includes bibliographical references.

Thesis (Ph.D.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: leaf 167-182.

Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 271-285.

Thesis (Ph.D.) -- University of Rhode Island, 2008. / Typescript. Includes bibliographical references (leaves 140-145).