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URN etd-0913111-163012 Statistics This thesis had been viewed 1819 times. Download 624 times. Author You-lin Chen Author's Email Address No Public. Department Materials Engineering Year 2010 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 97 Title Preparation and characterization of Li4Ti5(1-x)M5xO12 (M = Al or Mg, and 0 ≤ x ≤ 0.09 ) anode materials for Li- ion batteries Keyword anode material cation substitution. Spinel structure Li4Ti5O12 Li4Ti5O12 Spinel structure cation substitution. anode material Abstract Spinel Li4Ti5O12 and Li4Ti5(1-x)M5xO12 (M = Mg or Al, 0 ≤ x ≤ 0.09) samples were prepared via a sol-gel method followed by heat-treatment at various temperatures (800~ 1000oC). The crystal structure, composition, and morphology of the synthesized samples were investigated with XRD, ICP-OES, and SEM, respectively. The electrochemical properties of synthesized samples were also studied with capacity retention study and cyclic voltammetry. The XRD patterns showed spinel Li4Ti5O12 formed exclusively in the prepared sample. The calculated lattice parameter of spinel changes slightly with increasing heat-treating temperature, however, it increases/decreases with increasing amount of Mg2+/Al3+-substitution, respectively, for Li4Ti5(1-x)M5xO12 samples prepared at 850oC. The average particle size increases from 350 nm in 800oC prepared sample to 550 nm in 1000oC sample, though the variation in average particle size with amount of Mg2+ or Al3+-substitutions can be ignored. Among the Li4Ti5O12 samples prepared at various temperatures, 850oC prepared sample manifests the most promising initial charge/discharge capacities with cutoff voltages of 0.5 and 2.5 V. So the temperature was used for preparing Li4Ti5(1-x)M5xO12 powders. The samples with x = 0.01 for both Mg2+ and Al3+-substitutions exhibit the most promising cycling performance among the prepared Li4Ti5(1-x)M5xO12 samples with initial discharge capacities of 196, 170, and 146 mAh/g at 0.1, 1, and 5C rates, respectively. Advisor Committee She-huang Wu - advisor
Hong-Ming Lin - co-chair
Jeng-Yu Lin - co-chair
Nae-Lih Wu - co-chair
Files Date of Defense 2011-07-28 Date of Submission 2011-09-13