Spinel Li4Ti5O12 Synthesis via Hydrothermal Process and its Electrochemical Study
| Autor: | Erwin Rodriguez, 斐爾文 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 The hydrothermal synthesis is a soft-solution process, which operates near the ambient condition, and one of its greatest advantages is the possibility to synthesize materials with controlled the size and morphology. Nanocrystalline square particles, nano flakes or spherical secondary particles of Li4Ti5O12 (LTO) have been synthesized from TiO2 powder and LiOH via a hydrothermal treatment of water soluble titanium peroxide followed by thermal treatment. Titanium dioxide (TiO2) as a precursor has been employed in its different phases. The morphology of the resulting LTO products have strongly been found to depend on temperature, stoichiometric ratio of lithium titanium, concentration of hydrogen peroxide, and pH. With the latter parameters, the morphology was controlled obtaining square particles with narrow distribution size, nano flakes with less than 10 nm of thickness, and spherical secondary particles of the letter nano particles. The nanostructured LTO in powders serves to shorten the diffusion distance of lithium ion (path way) and enhances contact area between electrode and electrolyte, thus improving its high rate capability. Great performance at high C-rate has been delivered by the nano flakes morphology of LTO, which achieved 75 % (124 mAhg-1) of the capacity at 50 C-rate. The results show that the rate capability is in the following order: nano flakes powder > nano square particles powder > secondary particle of nano flakes powder > secondary particle of square particles powder. Upon cycling at 5 C-rate, all the LTO powders show good cycle stability, losing less than 7 % capacity after 900 cycles (for the square particles). |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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