Electrochimica Acta 74 (2012) 182–188 Contents lists available at SciVerse ScienceDirect Electrochimica Acta j ourna l ho me pag e: www.elsevier.com/locate/electacta Close-packed SnO 2 nanocrystals anchored on amorphous silica as a stable anode material for lithium-ion battery Junjie Cai a,1 , Zesheng Li a,1 , Shu Yao a , Hui Meng a , Pei Kang Shen a,∗ , Zidong Wei b,∗∗ a The State Key Laboratory of Optoelectronic Materials and Technologies, and Guangdong Province Key Laboratory of Low-carbon Chemistry & Energy Conservation, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China b Department of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, PR China a r t i c l e i n f o Article history: Received 27 February 2012 Received in revised form 14 April 2012 Accepted 14 April 2012 Available online 20 April 2012 Keywords: Li-ion batteries SnO2/silica Hybrid materials Sol–gel method Nanocrystal a b s t r a c t A sol–gel route has been used to synthesize close-packed SnO 2 nanocrystals anchored on amorphous silica as a potential anode material for lithium-ion battery. The materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, transmission electron microscopy (TEM) and electrochemical techniques. The electrochemical performance of the SnO 2 /silica composites shows higher capacity and good cycle stability compared with that of the bare SnO 2 electrode. It is believed that the good performance as a stable anode material originates from the unique structure of the close- packed nanocrystalline assemblies and the amorphous porous silica as inactive material to mediate the massive volume expansion and contraction of SnO 2 during lithiation and delithiation processes. It has been proved for the first time that the close-packed architecture of SnO 2 nanocrystals ensure adequate amount of active component for the lithium storage, resulting in a reasonable lithium storage capability for the present system. On the other hand, the crystalline/amorphous interactions should be one of the most fundamental factors to improve the electrochemical stability of the SnO 2 /silica hybrid electrode. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Besides the crystalline hybrid nanostructures, including core–shell [1], alloy [2], and bimetallic heterostructures [3], there has been increasing interest devoted toward the development of crystalline/amorphous hybrid nanomaterials for multifarious tech- nical applications [4]. These diphasic nanostructures combining distinct properties of the crystalline and amorphous components, yield unique hybrid nanosystems with multifunctional capabilities that may not be attainable otherwise [5]. Amorphous porous silica, with its remarkable adsorption property as well as high chemical and thermal stability, has become one of the most appealing blocks for building crystalline/amorphous hybrid architectures with accessible functionality [6]. Tin dioxide (SnO 2 ) currently is one of the attractive alternative anode materials for lithium-ion batteries because of its high spe- cific capacity relative to graphite [7]. Whereas, its application is still hindered by poor cycle ability originating from the huge volume ∗ Corresponding author. Tel.: +86 20 84113369; fax: +86 20 84113369. ∗∗ Corresponding author. E-mail addresses: stsspk@mail.sysu.edu.cn (P.K. Shen), zdwei@cqu.edu.cn (Z. Wei). 1 These two authors contributed equally to this work. change during Li–Sn alloying/dealloying cycle [8]. There are two typical approaches have been proposed attempting to solve this problem: (i) decreasing particle size of the SnO 2 to provide accom- modation of the strain of lithium insertion/removal [9] and (ii) introducing an inactive material to buffer the volume change and stabilize the active component [10]. Expressly, rational combina- tion of these two strategies by integrating SnO 2 nanocrystals onto an amorphous matrix might help basically improve their stability [11]. In previous studies, amorphous carbon are often choose for improving the cycling stability in lithium-ion batteries by structur- ing SnO 2 @C hybrid nanostructures, however, it still cannot satisfy people’s needs. In this regard, novel conceptions and new attempts were constantly to be put forward to increased electrochemical performance [12]. In this article, we make a new attempt on utilization of amor- phous porous silica as inactive material to mediate the massive volume expansion and contraction of SnO 2 during lithiation and delithiation processes. A simple sol–gel route was introduced to synchronously synthesize fine SnO 2 nanocrystals (6–8 nm) that were well supported on amorphous silica matrix, by using tetraethoxysilane (TEOS) and SnCl 2 as starting materials. More details were provided in Section 2. Our method inherited the feature advantages of traditional sol–gel procedures, such as the compositional homogeneity of the products and ability to con- trol the size of the particles [13]. Nonetheless, the silica sacrificial 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.04.045