Journal of Power Sources 163 (2006) 196–200 Short communication Effect of ultrasonic treatment and temperature on nanocrystalline TiO 2 D.H. Kim, H.W. Ryu, J.H. Moon, J. Kim ∗ Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-dong, Buk-ku, Gwangju 500-757, South Korea Received 8 August 2005; received in revised form 15 December 2005; accepted 20 December 2005 Available online 8 February 2006 Abstract Nanocrystalline TiO 2 particles were precipitated from the ethanol solution of titanium isopropoxide (Ti(O–iPr) 4 ) and H 2 O 2 by refluxing at 80 ◦ C for 48 h. The obtained particles were filtered and dried at 100 ◦ C for 12 h. The dried powder itself, the sample with heating at 400 ◦ C, and the sample with ultrasonically treating were prepared to investigate the effects of post treatments on materials characteristics and electrochemical properties of nanocrystalline TiO 2 . The X-ray diffraction patterns of all of the samples were fitted well to the anatase phase. The field emission-TEM image of as-prepared sample shows a uniform spherical morphology with 5 nm particle size and the sample heated at 400 ◦ C shows slightly increased particle size of about 10 nm while maintaining spherical shape. The sample treated with ultrasonic for 5 h or more at room temperature shows high aspect ratio particle shape with an average diameter of 5 nm and a length of 20 nm. According to the results of the electrochemical testing, as-prepared sample, the sample heated at 400 ◦ C for 3 h, and the sample treated with ultrasonic show initial capacities of 270, 310 and 340 mAh g -1 , respectively. © 2006 Elsevier B.V. All rights reserved. Keywords: Nanocrystalline; Particles; TiO 2 ; Morphology; Ultrasonic 1. Introduction The demand for high energy density, high capacity and high- rate capability rechargeable batteries has stimulated the search for new materials [1]. Various systems have been developed for lithium ion batteries employing graphite as an anode [2–5]. However, the graphite anode has some disadvantages such as its initial loss of capacity, structural deformation and electrical dis- connection. For example, when manganese-based cathodes are combined with graphite anodes, manganese reacts with elec- trolyte, LiPF 6 , and is dissolved to form MnF. This phenomenon has been proved to cause the degradation of electrochemical properties. To circumvent these problems, a various class of anode materials, transition metal oxides (MoO 2 , SnO 2 , Ta 2 O 5 , NiO, CoO, CuO, FeO and Li 4 Ti 5 O 12 ), have been investigated [6–9]. ∗ Corresponding author. Tel.: +82 62 530 1703; fax: +82 62 530 1699. E-mail address: jaekook@chonnam.ac.kr (J. Kim). Among these, titanium oxide has been found to be one of the good candidates as an anode for lithium ion batteries with advan- tages of a high capacity, low cost and non-toxicity. Huang et al. have showed a low capacity of 50 mAh g -1 for nano-size TiO 2 [8]. Natarajan et al. have reported amorphous, nanocrystalline and crystalline TiO 2 phases obtained by aqueous peroxo route show a maximum reversible discharge capacity of 140 mAh g -1 [10]. M. Hibino et al. have reported amorphous titanium oxide electrode for high-rate discharge and charge with a capacity of 120 mA g -1 under a high current density such as 10 A g -1 [11]. Zhou et al. have reported TiO 2 nanotube for anode material with a capacity of 184 mA g -1 in the voltage range of 1–3 V [12]. Abraham and co-workers have synthesized micrometer-sized Li 4 Ti 5 O 12 at 800 ◦ C using solid-state reaction with a capacity of 140 mAh g -1 [13,14]. We have investigated the influence of ultrasonic and heat treatments on nanocrystalline TiO 2 and its electrochemical prop- erties as an anode material in the lithium ion batteries. The objective was to obtain a better understanding of the synthe- sis conditions on characteristics of nanocrystalline TiO 2 so as to achieve desirable electrochemical performances. 0378-7753/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2005.12.060