Antimony-Doped SnO2 Nanopowders with High Crystallinity for Lithium-Ion Battery Electrode

Antimony-doped SnO2 (ATO) nanopowders with high crystallinity were obtained by a polymer-assisted sol-gel process based on a novel amphiphilic block-copolymer ("KLE" type, poly(ethylene-co-butylene)-block-poly(ethyleneoxide) and simple tin reagents (SnCl4 and Sb(OC2H5)(3)). As-synthesized samples were analyzed by Thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron micrographs (TEM), N-2 adsorption-desorption isotherms, and X-ray photoelectron spectroscopy (XPS). The results showed that the particles were the high crystalline ATO nanopowders of 5-8 nm, primary particle size and the Sb was indeed incorporated into the SnO2 crystal structure (cassiterite SnO2). The as-prepared samples were used as negative electrode materials for lithium-ion batteries, whose charge-discharge properties, cyclic voltammetry, and cycle performance were examined. A high initial discharge capacity about 2400 mA h g(-1) was observed at a constant discharge current density of approximately C/5 in a potential range of 0.005-3.0 V. A highly stable capacity of 637 mA h g(-1) after 100 cycles is substantially higher than that of most previously reported SnO2 nano-structures. The high reversible capacity for ATO nanopowders may be due to the presence of Sb for Sn, leading to an improved formation of metals with respect to structure and formation dynamics from ATO.