Journal of Power Sources 195 (2010) 5044–5048 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Short communication Improvement of electrochemical behavior of Sn 2 Fe/C nanocomposite anode with Al 2 O 3 addition for lithium-ion batteries Jae-Myung Lee a , Heechul Jung a , Yoon Hwa a , Hansu Kim b , Dongmin Im b , Seok-Gwang Doo b , Hun-Joon Sohn a,∗ a Department of Materials Science and Engineering, Research Center for Energy, Conversion and Storage, Seoul National University, Seoul 151-742, Republic of Korea b Energy and Environment Laboratory, Samsung Advanced Institute of Technology, Samsung Electronics, Giheung Gu, Yongin-Si, Gyeonggi-Gi Do, 446-712, Republic of Korea article info Article history: Received 9 January 2010 Received in revised form 5 February 2010 Accepted 9 February 2010 Available online 1 March 2010 Keywords: Anode Tin-based nanocomposite Lithium-ion battery Alumina Cycle performance capacity abstract Sn 2 Fe/Al 2 O 3 /C nanocomposites are synthesized using a high-energy, mechanical milling method with thermally synthesized Sn 2 Fe, Al 2 O 3 and carbon (Super P) powders. The effect of Al 2 O 3 addition on the microstructure of the Sn 2 Fe/Al 2 O 3 /C nanocomposites is examined. The electrochemical characteristics of the material as an anode in lithium-ion batteries are also evaluated. High-resolution transmission electron microscopy shows that the crystallite size of active Sn 2 Fe in the Sn 2 Fe/Al 2 O 3 /C nanocomposite is smaller than that of the Sn 2 Fe/C nanocomposite without Al 2 O 3 . A decrease in the initial irreversible capacity and enhanced cycle performance of the Sn 2 Fe/Al 2 O 3 /C nanocomposite electrode are observed. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Environmental pollution and the consumption of fossil fuels have driven the world to develop next-generation energy sources. Among them, lithium-ion batteries have become of great interest as power sources for mobile electric devices and electric vehicles [1–3]. At present, however, the commercial graphite-based anode has limited capacity (372 mAh g -1 ) [4] and anode materials with high specific energy are required [1,3,5]. Tin is an attractive anode material for Li-ion batteries on account of its large gravimetric capacity, i.e., as high as 959.5 mAh g -1 (Li 17 Sn 5 ). On the otherhand, the problems of capacity fading asso- ciated with Sn aggregation and extreme volume changes during the discharge–charge reaction have not been solved [6,7]. Composites consisting of an active and inactive component, nano-sized com- posites, amorphous materials and dispersion of the Sn particles in a carbon matrix have been examined in an attempt to solve these problems [8–13]. Following the release of Nexelion into the market by the Sony Corporation using an amorphous Sn-based composite anode con- sisting mainly of Sn, Co and carbon, cobalt-free Sn-transition metal alloys have attracted attention [14–20] because Co is expensive and toxic. Of these, a Sn–Fe/C composite would be a good candidate ∗ Corresponding author. Tel.: +82 2 880 7226; fax: +82 2 885 9671. E-mail address: hjsohn@snu.ac.kr (H.-J. Sohn). as an anode for lithium-ion batteries [21]. The Sn-Fe/C composite contains various intermetallic phases, such as Sn 2 Fe, SnFe, Sn 2 Fe 3 , Sn 3 Fe 5 and SnFe 3 , during synthesis of the composite. The reaction mechanism of the active materials (Sn 2 Fe, SnFe, and Sn 2 Fe 3 ) has been investigated by Dahn and co-workers [15–17]. Although the Sn 2 Fe/C composite shows a large specific capacity of 804 mAh g -1 , it still suffers from poor cycle performance and large irreversibility during the first cycle [15]. Mechanical stability is an important factor that affects the electrochemical performance of anode materials in lithium-ion bat- teries. During the discharge–charge reaction, a large volume change generates extreme stress and this gives rise to cracks and crum- bling, as well as the loss of electrical contact within the active materials [22]. Particulate-reinforced composites are reinforced mechanically by embedding ceramic particles, which impart high tensile strength and improved resistance to crack production and propagation [23–25]. The Mohs hardness of an Al 2 O 3 particle is 9 [26], and the addition of Al 2 O 3 particles is expected to reinforce the Sn 2 Fe/C nanocomposite materials and reduce the crystallite size of the active materials during a high-energy mechanical milling (HEMM) process. This study examines the effect of adding Al 2 O 3 particles on the microstructure of the Sn 2 Fe/Al 2 O 3 /C nanocomposites. In addition, the electrochemical characteristics of this material as an anode in lithium-ion batteries are also evaluated using a range of analytical techniques, and the results are compared with those for Sn 2 Fe/C nanocomposites. 0378-7753/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2010.02.068