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Please use this identifier to cite or link to this item: http://hdl.handle.net/2031/6157

Title: Li₄Ti₅O₁₂ anode for lithium ion batteries and thin film batteries
Other Titles: Li li zi dian chi he bo mo dian chi fu ji cai liao Li₄Ti₅O₁₂ de yan jiu
鋰離子電池和薄膜電池負極材料 Li₄Ti₅O₁₂ 的研究
Authors: Deng, Jianqiu (鄧健秋)
Department: Department of Physics and Materials Science
Degree: Doctor of Philosophy
Issue Date: 2010
Publisher: City University of Hong Kong
Subjects: Lithium cells -- Materials.
Thin film devices.
Anodes.
Notes: CityU Call Number: TK2945.L58 D46 2010
xxi, 152 leaves : ill. (some col.) 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2010.
Includes bibliographical references (leaves 131-152)
Type: thesis
Abstract: As the demand for the better, lighter and more efficient microelectronic portable devices increases, the development of novel thin film lithium ion batteries as power sources with high performance becomes essential. Within this body of work, Li4Ti5O12 thin film anodes have been prepared, characterized and evaluated for their electrochemical performance and kinetic behavior. Nano-sized spinel Li4Ti5O12 powders were synthesized by sol-gel method. The average grain size of the synthesized powders was around 700 nm. These Li4Ti5O12 electrode materials showed excellent electrochemical performance, which was satisfactory for preparing the target. Pure LiNi0.35Co0.35Mn0.30O2 powders were also successfully synthesized by hydroxide co-precipitation method. The LiNi0.35Co0.35Mn0.30O2 cathodes exhibited good cycling performance and rate capability. The initial discharge capacity was 143 mAhg-1 at 2 C-rate between 2.5 and 4.3 V, and the capacity retention of cathode was found 85% after 30 cycles. The Li(Ni0.35Co0.35Mn0.3)O2/Li4Ti5O12 cell system showed high specific capacity and good rate capability. However, the capacity fading was slightly fast. The ac impedance spectra analysis confirmed indirectly the somewhat bigger capacity loss. Spinel Li4Ti5O12 thin film electrodes for lithium ion batteries were prepared by pulsed laser deposition technique for the first time. All films crystallized well and exhibited good electrochemical performances. The influence of annealing temperatures on electrochemical performances of film electrodes was also investigated. The optimal As the demand for the better, lighter and more efficient microelectronic portable devices increases, the development of novel thin film lithium ion batteries as power sources with high performance becomes essential. Within this body of work, Li4Ti5O12 thin film anodes have been prepared, characterized and evaluated for their electrochemical performance and kinetic behavior. Nano-sized spinel Li4Ti5O12 powders were synthesized by sol-gel method. The average grain size of the synthesized powders was around 700 nm. These Li4Ti5O12 electrode materials showed excellent electrochemical performance, which was satisfactory for preparing the target. Pure LiNi0.35Co0.35Mn0.30O2 powders were also successfully synthesized by hydroxide co-precipitation method. The LiNi0.35Co0.35Mn0.30O2 cathodes exhibited good cycling performance and rate capability. The initial discharge capacity was 143 mAhg-1 at 2 C-rate between 2.5 and 4.3 V, and the capacity retention of cathode was found 85% after 30 cycles. The Li(Ni0.35Co0.35Mn0.3)O2/Li4Ti5O12 cell system showed high specific capacity and good rate capability. However, the capacity fading was slightly fast. The ac impedance spectra analysis confirmed indirectly the somewhat bigger capacity loss. Spinel Li4Ti5O12 thin film electrodes for lithium ion batteries were prepared by pulsed laser deposition technique for the first time. All films crystallized well and exhibited good electrochemical performances. The influence of annealing temperatures on electrochemical performances of film electrodes was also investigated. The optimal electrochemical impedance spectroscopy (EIS). The values of DLi depended on the cell voltage and were independent of the thickness of film electrodes. The values of DLi derived from experimental results by different methods were in a quite wide range of 10−16 ~ 10−9 cm2s−1. The kinetic parameters obtained from impedance spectra and the variations of the DLi values as a function of cell voltage could be correlated with the electrochemical performance of film electrodes. The decrease of the DLi value during the discharging process can be explained by the two-phase transition during lithium insertion into Li4Ti5O12 anode. In the same way, the two-phase transition could be verified by the variation of lithium ion chemical diffusion coefficient.
Online Catalog Link: http://lib.cityu.edu.hk/record=b3947653
Appears in Collections:AP - Doctor of Philosophy

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