Electrochemical evaluation of nanocrystalline Zn-doped tin oxides as anodes for lithium ion microbatteries

Nanocrystalline tin oxides were synthesized using electron beam evaporation (e-beam) and further heat treatment. X-ray diffraction (XRD) revealed that as-deposited samples were amorphous SnO. Heat treatment of the as-deposited thin films at 250 degrees C for 2 h and 500 degrees C for 10 h led to the formation of romarchite SnO and tetragonal SnO2, respectively. Scanning electron microscopy (SEM) showed a compact morphology of the coatings. Elemental mapping of the films also represented homogeneous distribution of the zinc atoms in the SnO2 structure. Atomic force microscopy (AFM) images demonstrated a fine and smooth surface of the e-beam evaporated films for the SnO samples, and rough topography for the SnO2. Doping led to the formation of finer and more uniform surface morphology. Anodic behavior of the thin film during charge/discharge process showed that specific capacity of the pure SnO2 increased from 502 to 903 mu Ah cm(-2) mu m(-1) for nanocrystalline Zn-doped SnO2. Moreover, specific capacity of the doped film enhanced to 137.6 that is, higher than 69.5 mu Ah cm(-2) mu m(-1) for the pure SnO2. XRD results also show that Zn doping decreased Sn clustering during cycling. (C) 2010 Elsevier B.V. All rights reserved.