Issue 29, 2014

C-axis preferentially oriented and fully activated TiO2 nanotube arrays for lithium ion batteries and supercapacitors

Abstract

We report the fabrication of long titanium dioxide nanotube arrays with highly c-axis preferentially oriented crystallization and a high concentration of oxygen vacancies by second anodization in ethylene glycol and annealing under poor-oxygen conditions. By optimizing the growth and annealing conditions, the [001] oriented crystallization is maximized, and 31.7% of the total Ti ions exists as Ti3+ ions. The carrier density of the [001]-oriented TiO2 nanotube arrays is two orders of magnitude higher than that of the randomly oriented TiO2 nanotube arrays. The unusual c-textured crystallization confined within nanotubes may involve the formation of TiO62− octahedra with a gradient distribution along the tube axis, preferential nucleation at the top, and preferential growth downwards along the c axis. Because of the c-axis preferential orientation and a high-concentration of oxygen vacancies, long TiO2 nanotube arrays can serve as superior electrodes for both lithium ion batteries and supercapacitors without the addition of any conductive agents. Long c-oriented TiO2 nanotube arrays deliver reversible capacities of 293 mA h g−1 at 0.5 C and 174 mA h g−1 at 5 C with Coulombic efficiencies of over 99%, and hold an areal capacitance of 8.21 mF cm−2 with an 85% capacitance retention after 5000 cycles. Double roles played by oxygen vacancies are identified in increasing electrical conductivity and activating the rich-Li phase.

Graphical abstract: C-axis preferentially oriented and fully activated TiO2 nanotube arrays for lithium ion batteries and supercapacitors

Supplementary files

Article information

Article type
Paper
Submitted
03 4 2014
Accepted
10 5 2014
First published
14 5 2014

J. Mater. Chem. A, 2014,2, 11454-11464

Author version available

C-axis preferentially oriented and fully activated TiO2 nanotube arrays for lithium ion batteries and supercapacitors

D. Pan, H. Huang, X. Wang, L. Wang, H. Liao, Z. Li and M. Wu, J. Mater. Chem. A, 2014, 2, 11454 DOI: 10.1039/C4TA01613K

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