Data from: Effect of Hf-doping on electrochemical performance of anatase TiO2 as an anode material for lithium storage
Gnedenkov, Sergey V. et al. (2018), Data from: Effect of Hf-doping on electrochemical performance of anatase TiO2 as an anode material for lithium storage, Dryad, Dataset, https://doi.org/10.5061/dryad.gf63r
Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol-gel method on carbon fiber. Physicochemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis, and Brunauer−Emmett−Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1–xHfxO2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1–xHfxO2 materials are hollow microtubes (length of 10–100 μm, outer diameter of 1–5 μm) composed of nanoparticles (average size of 15–20 nm) with surface area of 80–90 m2 g–1 and pore volume of 0.294–0.372 cm3 g–1. The effect of hafnium ions incorporation on electrochemical behavior of anatase TiO2 as Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g–1) after 35-fold cycling at C/10 rate in comparison with undoped titania (55.9 mAh g–1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in a strong accordance with ones for anatase TiO2 doped via Zr4+ (0.72 Å) published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials due to charge redistribution in the lattice and enhanced interfacial lithium storage due to increased surface area directly depending on Hf/Ti atomic ratio have beneficial effect on electrochemical properties.