The Preparation Of Ni Doped SnO₂ Nanostructures And Its Application In Li-ion Battery

Tin dioxide is a chemical stable transparent semiconductor with a wide bandgap. Owing to its low resistivity and high transmittance as well as other excellent physical and chemical properties, SnO2 is widely used in many fields such as gas sensors, transparent conducting electrodes, Li-ion battery anode, etc.Undoped and Ni-doped SnO2 nanostructures such as nanocubes, nanospheres and hollow spheres were synthesized by a simple hydrothermal method. The as-prepared and annealed Sn1-xNixO2 were characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectrum, UV-Vis absorption spectra, and room temperature photoluminescence spectra.UV-Vis absorption spectra show that the undoped SnO2 exhibits high transmittance within the visible spectra. While for those Ni-doped SnO2 samples, new absorbance ranging from 600 to 800 nm were observed, and the intensity of the absorbance enhance with increasing Ni ions concentration. Besides, Ni doping also makes the onset of absorbance a shift from about 400 nm to 500 nm. Room temperature photoluminescence spectra of the as-synthesized samples display a strong yellow emission at about 600 nm and a weak blue emission at about 430 nm. By investigating the relationship between the Raman band centered at 560 cm-1 and the photoluminescence of the samples, we suggest that the broad yellow emission and weak blue emission primarily originate from singly ionized oxygen vacancies and tin interstitials, respectively.Electrochemical properties of undoped and Ni-doped SnO2 nanostructures as negative electrode of lithium ion batteries were studied by constant current charge/discharge testing, which show that the undoped SnO2 hollow microspheres electrode has a surprisingly large initial discharge capacity of 1650 mAh/g, but poor cyclic performance and low capacity retention, which was only 130mAh/g after 40 cycles. Ni doping can improve the cyclic performance apparently, and there remains a capacity of as high as 230 mAh/g after 40 cycles for the 2mol% Ni doped SnO2 electrode.