Thesis (Ph. D.)--University of Chicago, Dept. of Physics, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis--M. Phil., University of Hong Kong, 1983.

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. / text

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

Η παρούσα εργασία πραγματεύεται την τεκτονική ανάλυση της ευρύτερης περιοχής της Περαχώρας του νομού Κορινθίας, η οποία βρίσκεται σε απόσταση 12km βόρεια του Λουτρακίου. Για την ανάλυση των γεωλογικών μορφών της περιοχής λήφθησαν μετρήσεις με γεωλογική πυξίδα, οι οποίες προβλήθηκαν σε στερεογραφικά δίκτυα για εξαγωγή συμπερασμάτων. Βάσει των μετρήσεων αυτών κατασκευάστηκαν γεωλογικές τομές (ΑΑ΄ και ΒΒ΄) οι οποίες απεικονίζουν τις επωθήσεις στο χωριό Πίσσια. / This work deals with -the structural analysis of the broader region of Perachora in the prefecture of Corinth-, located 12 km north of Loutraki. In order to describe the structural architecture of the region have been taken measurements using a geological compass and then the orientation data were projected to stereographic nets. Based on these measurements there have been made geological cross-sections.

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