title: Anatase titania nanorods as an intercalation anode material for rechargeable sodium batteries.
abstract: For the first time, we report the electrochemical activity of anatase TiO2 nanorods in a Na cell. The anatase TiO2 nanorods were synthesized by a hydrothermal method, and their surfaces were coated by carbon to improve the electric conductivity through carbonization of pitch at 700 °C for 2 h in Ar flow. The resulting structure does not change before and after the carbon coating, as confirmed by X-ray diffraction (XRD). Transmission electron microscopic images confirm the presence of a carbon coating on the anatase TiO2 nanorods. In cell tests, anodes of bare and carbon-coated anatase TiO2 nanorods exhibit stable cycling performance and attain a capacity of about 172 and 193 mAh g(-1) on the first charge, respectively, in the voltage range of 3-0 V. With the help of the conductive carbon layers, the carbon-coated anatase TiO2 delivers more capacity at high rates, 104 mAh g(-1) at the 10 C-rate (3.3 A g(-1)), 82 mAh g(-1) at the 30 C-rate (10 A g(-1)), and 53 mAh g(-1) at the 100 C-rate (33 A g(-1)). By contrast, the anode of bare anatase TiO2 nanorods delivers only about 38 mAh g(-1) at the 10 C-rate (3.3 A g(-1)). The excellent cyclability and high-rate capability are the result of a Na(+) insertion and extraction reaction into the host structure coupled with Ti(4+/3+) redox reaction, as revealed by X-ray absorption spectroscopy.
authors.affiliation: Department of Nano Engineering, Sejong University , Seoul 143-747, South Korea.
authors.forename: Ki-Tae
authors.initials: KT
authors.lastname: Kim
authors.forename: Ghulam
authors.initials: G
authors.lastname: Ali
authors.forename: Kyung Yoon
authors.initials: KY
authors.lastname: Chung
authors.forename: Chong Seung
authors.initials: CS
authors.lastname: Yoon
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yashiro
authors.forename: Yang-Kook
authors.initials: YK
authors.lastname: Sun
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Khalil
authors.initials: K
authors.lastname: Amine
authors.forename: Seung-Taek
authors.initials: ST
authors.lastname: Myung