265278 Porous SnO2 Helical Nanotubes and Sheets for Lithium-Ion Batteries

Thursday, November 1, 2012: 3:15 PM
Cambria East (Westin )
Ling Fei1, Yun Xu1 and Hongmei Luo2, (1)Chemical Engineering Department, New Mexico State University, Las cruces, NM, (2)Chemical Engineering Department, New Mexico State University, Las Cruces, NM

Motivated by the growing interest in lithium-ion batteries and the good electrochemical performance of Sn-based materials, we report a surfactant-free chemical solution route for synthesizing porous SnO2 helical nanotubes templated by helical carbon nanotubes and SnO2 sheets templated by graphite sheets. Transmission electron microscopy, X-ray diffraction, cyclic voltammetry, and galvanostatic discharge-charge analysis are used to characterize the SnO2 samples. The unique nanostructure and morphology make them promising anode materials for lithium-ion batteries. The discharge capacities in the first and the second cycles are 1252 and 1146 mAh/g for SnO2 nanotubes, and 1039 and 973 mAh/g for SnO2 sheets. On the other hand, the charge capacities in the first and the second cycles are 1212 and 1105 mAh/g for SnO2 nanotubes, 1016 and 950 mAh/g for SnO2 sheets. The first-cycle irreversible capacity loss is 3.2 % and 2.2 % for the nanotubes and sheets, respectively. The SnO2 helical nanotubes show a specific capacity of above 800 mAh/g after 10 charge and discharge cycles, exceeding the theoretical capacity of 781 mAh/g for SnO2. After 30 cycles, the SnO2 nanotubes still exhibit a discharge capacity of 439 mAh/g and the sheets have a discharge capacity of 323 mAh/g. The capacity of SnO2 helical nanotubes is higher than that of the SnO2 nanotubes (less than 300 mAh/g after 30 cycles) prepared by a sol-gel vacuum-suction method using AAO as templates; the SnO2 nanotubes (240 mAh/g after 20 cycles) prepared by hydrothermal method using Sn nanorods as sacrificial templates; and the SnO2-carbon nanotubes composite (345 mAh/g). It is also confirmed that the SnO2 samples with the one-dimensional tubular structure show better electrochemical performance than the two-dimensional sheet structure.

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