Facile Approach to Prepare Porous CaSnO 3 Nanotubes via a Single Spinneret Electrospinning Technique as Anodes for Lithium Ion Batteries Linlin Li, †,# Shengjie Peng, † Jin Wang, † Yan Ling Cheah, † Peifen Teh, † Yahwen Ko, † Chuiling Wong, † and Madhavi Srinivasan* ,†,# † School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798 # TUM-CREATE Center for Electromobility, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 * S Supporting Information ABSTRACT: CaSnO 3 nanotubes are successfully prepared by a single spinneret electrospinning technique. The characterized results indicate that the well-crystallized one-dimensional (1D) CaSnO 3 nanostructures consist of about 10 nm nanocrystals, which interconnect to form nanofibers, nanotubes, and ruptured nanobelts after calcination. The diameter and wall thickness of CaSnO 3 nanotubes are about 180 and 40 nm, respectively. It is demonstrated that CaSnO 3 nanofiber, nanotubes, and ruptured nanobelts can be obtained by adjusting the calcination temperature in the range of 600- 800 °C. The effect of calcination temperature on the morphologies of electrospun 1D CaSnO 3 nanostructures and the formation mechanism leading to 1D CaSnO 3 nanostructures are investigated. As anodes for lithium ion batteries, CaSnO 3 nanotubes exhibit superior electrochemical performance and deliver 1168 mAh g -1 of initial discharge capacity and 565 mAh g -1 of discharge capacity up to the 50th cycle, which is ascribed to the hollow interior structure of 1D CaSnO 3 nanotubes. Such porous nanotubular structure provides both buffer spaces for volume change during charging/discharging and rapid lithium ion transport, resulting in excellent electrochemical performance. KEYWORDS: CaSnO 3 nanotubes, CaSnO 3 nanofibers, electrospinning, lithium ion batteries, anodes, electrochemical performance 1. INTRODUCTION Lithium ion batteries (LIBs), as a versatile power source, have been widely used in various portable electronic devices. With the development of advanced technologies, research focus is on high energy LIBs 1,2 that are suitable for applications in electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). Such applications ideally require LIBs of high energy density, high power, good cycling performance, excellent safety, thermal stability, low cost, and low toxicity. To achieve high energy density, novel materials are required to replace presently used graphite anodes (theoretical specific capacity 372 mAh g -1 ). Currently, various transition metal oxides (TMOs) have been extensively studied as promising LIBs anode substitutes due to their high theoretical capacity (∼400-900 mAh g -1 ). 3 These metal oxides react with lithium via two main approaches: Alloying/dealloying reaction, + → + + + ↔ + − x x MO 2Li M Li O and M Li e Li M 2 x (1) Conversion reaction, + + ↔ + − + n n x M O e Li M Li O x v 0 n v (2) Among various TMOs, Sn-based binary and ternary oxides 4-9 are particularly attractive alternatives to graphite anodes, owing to their improved safety and high theoretical reversible capacity (782 mAh g -1 ) at a lower potential versus Li, which is more than twice that of currently used graphite (372 mAh g -1 ). Unfortunately, the main hindrance against commercial use of Sn-based anode materials in LIBs is the poor capacity retention over extended charge-discharge cycling. This problem mainly originates from the large, uneven volume changes (∼300%) that take place upon lithium insertion and extraction within Sn-based oxides, ultimately resulting in cracking and pulverization of the grains leading to loss of contact between individual grains. 10,11 To alleviate this problem, one of the promising ways is to form Tin-based composite oxides (TCO) in which the homogeneous electro- chemically active/inactive matrixes like MO x and carbon may accommodate the volume change and inhibit the aggrega- tion. 12-15 Hence, a series of stannates such as M 2 SnO 4 (M = Zn, Mg, Mn, Co, Ca), 16-20 ASnO 3 (A = Ca, Sr, Ba, Co, Cd), 21-30 and Received: August 15, 2012 Accepted: October 17, 2012 Published: October 17, 2012 Research Article www.acsami.org © 2012 American Chemical Society 6005 dx.doi.org/10.1021/am301664e | ACS Appl. Mater. Interfaces 2012, 4, 6005-6012