Lithium ion insertion properties of nanocrystalline anatase titanium oxides prepared from peroxo-polytitanic acid

Peroxo-polytitanic acid (Ti-iPA) solution was obtained by using a reaction between metallic Ti powder and 30 wt.% aq. H2O2. Amorphous titanium oxide was prepared by drying Ti-iPA solution at 115 °C, and nanocrystalline anatase titanium oxide was prepared by heating the amorphous phase at 300–500 °C. The crystal structure was the same as that of the conventional anatase form. The anatase titanium oxide obtained by heating at 300 °C for 5 h with an average particle size of 25 nm showed the capacity of 158 mA h/g as negative electrode for lithium ion batteries. The capacity was increased with increasing the heating time at 300 °C and reduced with increasing the heating temperature to 400–500 °C. The lithium insertion/deinsertion performance was enhanced by heating at 300 °C because lattice defects were reduced without crystal growth and aggregation. We also calculated site energy distribution from the deconvolution of experimental discharge curves, and discussed the relationship between the structure and the insertion site.