The Effect of Thermal Treatment on the Morphology and Structure of SnO2/TiO2 Composite Micro-fibers

Tin oxide and titanium oxide (SnO2/TiO2) composite fibers were prepared from polyvinylpyrrolidone (PVP)/SnO2/TiO2 precursor solutions with different SnO2 to TiO2 ratios of 1:1, 2:1, 3:1, and 3:2. The precursor fibers were thermally treated using different heating rates to prepare SnO2/TiO2 fibers with micro-belt morphology. The characterization of the SnO2/TiO2 composite fibers was performed using a scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermogravimetric analysis (TGA). The SEM images showed that the fibers were flat and had micron-sized diameters. EDS mapping of the precursor fibers showed the fibers to have a distribution of Sn and Ti throughout the surface with areas of high concentration of carbon, nitrogen, and oxygen. The XRD, XPS, and Raman data confirmed the presence of SnO2/TiO2. Initial electrochemical testing of Li-ion half cells, using SnO2/TiO2 as anode material, showed the composite fibers with different ratios to have higher specific capacity and slower anode pulverization than SnO2. The results reported in this work showed that SnO2/TiO2 composite fibers with micro-belt morphology could be achieved, and the synthesis was susceptible to both the temperature ramp rate during calcination of the precursor fibers and the SnO2 to TiO2 ratio in the composite fibers.