Article pubs.acs.org/JPCC
Sb:SnO2@TiO2 Heteroepitaxial Branched Nanoarchitectures for Li Ion Battery Electrodes Sangbaek Park,† Seung-Deok Seo,‡ Sangwook Lee,§ Se Won Seo,† Kyung-Soo Park,‡ Chan Woo Lee,† Dong-Wan Kim,*,‡ and Kug Sun Hong*,† †
Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, Korea Department of Materials Science and Engineering, Ajou University, Suwon 443-749, Korea § Department of Material Science and Engineering, University of California at Berkeley, California 94709, United States ‡
S Supporting Information *
ABSTRACT: High-quality, single-crystalline Sb-doped SnO2 (ATO) nanobelts (NBs) surrounded by very thin and short TiO2 rutile nanorods were synthesized by thermal evaporation followed by chemical bath deposition. An epitaxial relationship between ATO NBs and rutile-phase TiO2 nanorods was clearly demonstrated on the basis of a crystallographic approach through high-resolution transmission electron microscopy analysis. Furthermore, the ATO@TiO2 heteronanostructures as anodes for Li ion batteries showed enhanced cycling stability and superior rate capabilities. These improved electrochemical performances were attributed to beneficial geometrical, structural, and doping effects such as alleviation of volume expansion, epitaxial growth, and high electronic conductivity.
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electrodes (theoretical capacity 372 mA h g−1) for Li-ion rechargeable batteries, because of its higher theoretical capacity (782 mA h g−1). However, the huge volume expansion/ contraction (∼300%) of SnO2-based anodes that occurs during the Li-alloying/dealloying process is the most critical problem to be overcome for practical application. These volume changes lead to electrical isolation by crack and pulverization, resulting in poor cycle life of the electrode. To mitigate the pulverization problem of SnO2-based anodes, several strategies have been proposed, such as nanoarchitecturing of the electrode and formation of SnO2−carbon composites.17−20 Nanostructured materials, especially nanowires, can accommodate large strain without severe pulverization,18,21 and carbon-based materials can play a role in structural buffering as well as passage for facial electron transport.19,20 Furthermore, wrapping the surface of Sn-based nanostructures in other anode materials that show low volume variation during cycling could be an appropriate solution for the improvement of cycle life of the electrodes. In this respect, TiO2 that is a well-known anode material for Li-ion batteries having a theoretical capacity of 168 mA h g−1 and showing a low amount of volume change (
