Amorphous and Nanocrystalline Anatase Titanium Dioxides Prepared from Peroxo-Polytitanic Acid and Their Electrochemical Properties

Abstract

Peroxo-polytitanic acid solution was obtained by a reaction between metallic Ti powder and 30 wt% H2O2 aq. Amorphous titanium dioxide was obtained as its dried residue at 115 °C, and nanocrystalline anatase titanium dioxide was obtained by heating the amorphous phase at 300 – 500 °C. The anatase titanium dioxide with average particle size of 25 nm obtained by heating at 300 °C for 5h showed the capacity of 158 mAh/g as negative electrode for lithium ion batteries. The capacity was increased with increasing the heating time at 300 °C. Lattice defects were reduced by heating at 300 °C without crystal growth and aggregation, and this enhanced the lithium insertion/deinsertion performance. We also calculated site energy distribution from the deconvolution of experimental discharge curves, and discussed the relationship between the structure and the insertion site.