Lithium Storage in Amorphous TiO[sub 2] Nanoparticles

Amorphous titanium oxide nanoparticles were prepared from titanium isopropoxide. In situ measurements reveal an extraordinary high capacity of 810 mAh/g on the first discharge. Upon cycling at a charge/discharge rate of 33.5 mA/g, this capacity gradually decreases to 200 mAh/g after 50 cycles. The origin of this fading was investigated using X-ray absorption spectroscopy and solid-state nuclear magnetic resonance. These measurements reveal that a large fraction of the total amount of the consumed Li atoms is due to the reaction of species adsorbed at the surface to , explaining the irreversible capacity loss. The reversible capacity of the bulk, leading to the composition, does not explain the relatively large reversible capacity, implying that part of at the surface may be reversible. The high reversible capacity, also at large (dis)charge rates up to 3.35 A/g (10C), makes this amorphous titanium oxide material suitable as a low cost electrode material in a high power battery.