2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 9. Energy Production, Secondary Battery
| Editors: | F. Kongoli, H. Dodds, M. Mauntz, T. Turna, V. Kumar, K. Aifantis |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 170 pages |
| ISBN: | 978-1-987820-98-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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High Performance of Chemically Modified TiO2 Nanotubes for Lithium-ion Microbatteries
Thierry Djenizian1;1ECOLE DES MINES SAINT-ETIENNE, Gardanne, France;
Type of Paper: Regular
Id Paper: 203
Topic: 14
Abstract:
Modern microelectronic devices such as backup power for computer memories, MicroElectroMechanical Systems (MEMS), medical implants, smart cards, Radio-Frequency Identification (RFID) tags, and remote sensors have necessitated the development of high performance power sources at the microscale. In this context, the development of three-dimensional (3D) microbatteries forms a viable alternative to provide high volumetric energy densities to meet the demands of these devices.[1] The development of nano-architectured electrodes is one of the most promising approaches to realize the 3D paradigm of microbatteries.[2] Among all the potential anode materials, TiO<sub>2</sub> nanotubes (TiO<sub>2</sub>-NTs) possess remarkable characteristics for the design of 3D Li-ion microbatteries. Self-organized nanotubular materials allow a good diffusion of Li ions in the porous structures, and the 1D morphology allows an efficient charge transfer along the axis of the tube that results in a good apparent electronic conductivity of the TiO<sub>2</sub>-NTs layer, when compared to a film composed of nanoparticles [3,4]. Anatase TiO<sub>2</sub> can accommodate only 0.5 Li<sup>+</sup> per formula unit, corresponding to a theoretical capacity of 168 mAh g<sup>-1</sup>. Hence, several approaches have been investigated to improve the overall performance of TiO<sub>2</sub>-NTs for the design of high-performance Li-ion microbatteries. Doping with aliovalent ions like Niobium (Nb<sup>5+</sup>) is also a facile strategy to modify the electronic properties of titanium oxide and thereby enhance the electrochemical performance.[5,6] <br />We report the fabrication of self-supported Nb doped TiO<sub>2</sub>-NTs by anodization of Nb/Ti alloys devoid of any carbon additives or binders. An increase in the capacity of the TiO<sub>2</sub>-NTs was observed as the Nb doping concentration increased. Such a composition of 10 wt.% Nb doped TiO<sub>2</sub>-NTs (Nb10-TiO<sub>2</sub>-NTs) showed a first cycle capacity of 200 mAh.g<sup>-1</sup> (0.144 mAh.cm<sup>-2</sup>) compared to pristine TiO<sub>2</sub>-NTs, which gave a capacity of 115 mAh.g<sup>-1</sup> (0.078 mAh.cm<sup>-2</sup>) at C/10. Galvanostatic cycling tests at various C-rates revealed the influence of Nb doping in the TiO<sub>2</sub>-NTs. Compared to pristine TiO<sub>2</sub>-NTs, the discharge capacities of doped nanotubes are improved and almost doubled when the Nb concentration reaches 10 wt.%. Besides a good cycling behaviour at multiple C-rates, an overall capacity retention of 87 % is achieved after 100 cycles. According to Electrochemical Impedance Spectroscopy measurements, the enhanced electrochemical performance of the Nb-doped TiO<sub>2</sub>-NTs is attributed to their higher electronic conductivity.