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High energy and power density TiO2 nanotube electrodes for 3D Li-ion microbatteries
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Stockholm University.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
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2013 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 1, no 28, 8160-8169 p.Article in journal (Refereed) Published
Abstract [en]

Highly ordered anodic TiO2 nanotube arrays with a tube length of 9 [small mu ]m are shown to provide areal capacities of 0.24 mA h cm-2 (i.e. 96 mA h g-1) at a charge/discharge current density of 2.5 mA cm-2 (corresponding to a rate of 5 C) and 0.46 mA h cm-2 (i.e. 184 mA h g-1) at 0.05 mA cm-2, when used as 3D free-standing anodes in Li-ion microbatteries. The present nanotube electrodes, which could be cycled for 500 cycles with only 6% loss of capacity, exhibited significantly higher energy and power densities, as well as an excellent cycling stability compared to previously reported TiO2-based Li-ion microbattery electrodes. The influence of parameters such as ordering, geometry and crystallinity of the nanotubes on the microbattery performance was investigated. A two-step anodization process followed by annealing of the nanotubes was found to yield the best microbattery performance. It is also demonstrated that the rate capability of the electrode depends mainly on the rate of the structural rearrangements associated with the lithiation/delithiation reaction and that the areal capacity at various charge/discharge rates can be increased by increasing the tube wall thickness or the length of the nanotubes, up to 0.6 mA h cm-2 for 100 cycles.

Place, publisher, year, edition, pages
2013. Vol. 1, no 28, 8160-8169 p.
National Category
Nano Technology
Research subject
Materials Science
Identifiers
URN: urn:nbn:se:uu:diva-202840DOI: 10.1039/C3TA11273JISI: 000320876000012OAI: oai:DiVA.org:uu-202840DiVA: diva2:633916
Funder
Swedish Research Council
Available from: 2013-06-27 Created: 2013-06-27 Last updated: 2014-12-15
In thesis
1. From Current Collectors to Electrodes: Aluminium Rod Structures for Three-dimensional Li-ion Micro-battery Applications
Open this publication in new window or tab >>From Current Collectors to Electrodes: Aluminium Rod Structures for Three-dimensional Li-ion Micro-battery Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The potential use of 3D aluminium nanorod structures as current collectors and negative electrodes for 3D Li-ion micro-batteries was studied based on the use of relatively simple and cost-effective electrochemical and sol-gel deposition techniques.

Aluminium rod structures were synthesised by galvanostatic electrodeposition using commercial porous membranes as templates. It was shown that the use of a short (i.e., 50 ms long) potential pulse (i.e., -0.9 V vs. Al3+/Al) applied prior to a pulsed current electrochemical deposition gave rise to homogeneous deposits with more even rod heights.  Electrophoretic and sol-gel deposition of TiO2 on the same substrates were also studied. The use of the sol-gel technique successfully resulted in a thin coating of amorphous TiO2 on the Al nanorod current collector, but with relatively small discharge capacities due to the amorphous character of the deposits. Electrophoretic deposition was, however, successful only on 2D substrates. Anodisation of titanium was used to prepare 3D TiO2 nanotube electrodes, with a nanotube length of 9 um and wall thickness of 50 nm. The electrodes displayed high and stable discharge capacities of 460 µAh/cm2 at a 0.1 C rate upon prolonged cycling with good rate capability.

The 3D aluminium nanorod structures were tested as negative electrodes for Li-ion cells and the observed capacity fading was assigned to trapping of LiAl alloy inside the aluminium electrode caused by the diffusion of lithium into the electrode, rather than to pulverisation of the aluminium rods. The capacity fading effect could, however, be eliminated by decreasing the oxidation potential limit from 3.0 to 1.0 V vs. Li+/Li. A model for the alloying and dealloying of lithium with aluminium was also proposed. Finally, a proof-of-concept for a full 3D Li-ion micro-battery with electrodes of different geometries was demonstrated. The cell comprised a positive electrode, based on LiFePO4 deposited on a carbon foam current collector, with an area gain factor an order of magnitude larger than that for the Al nanorod negative electrode. This concept facilitates the balancing of 3D Li-ion cells as the positive electrode materials generally have significant lower specific energy densities than the negative electrodes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 63 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1110
Keyword
3D micro-batteries, aluminium, titanium oxide, current collectros, negative electrodes, electrodepostion, electrophoretic depostion, sol-gel synthesis
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-215482 (URN)978-91-554-8847-5 (ISBN)
Public defence
2014-02-28, Ångström 2001, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2014-02-06 Created: 2014-01-14 Last updated: 2014-02-10

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Wei, WeiOltean, GabrielEdström, KristinaBjörefors, FredrikNyholm, Leif

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