| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 101 === Spinel Li4Ti5O12/C samples with various Li/Ti atomic ratios (0.72 ~ 0.9) were prepared via a spray drying method followed by heat-treatment at 800°C under N2 atmosphere. The crystal structure, morphology, and electrochemical properties of the as-synthesized samples were investigated by XRD, FE-SEM, FE-TEM, and capacity retention studies. Spinel Li4Ti5O12 with Fd-3m space group was found exclusively in sample prepared with Li/Ti = 0.82. In addition to the Fd-3m phase, minor amount of anatase TiO2 was detected in samples prepared with Li/Ti ratio between 0.72 and 0.80 and Li2TiO3 could also be clearly observed in powders obtained from precursors with Li/Ti ratio higher than 0.82. From the results of capacity retention study, the sample prepared with Li/Ti = 0.82 exhibits the highest initial charge capacities of 164.1 mAh g-1 among the prepared samples. However, the sample prepared with Li/Ti = 0.72 shows most promising cycling performance at 1, 3, and 5C charge capacity of 163.0 mAh g-1, 161.7 mAh g-1 and 156.2 mAh g-1 after 30 cycles among the prepared samples. It may be due to the existence of anatase TiO2 that improve the electric conductivity of the sample.
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