Facile synthesis and electrochemical characterization of porous and dense TiO2 nanospheres for lithium-ion battery applications

We present a two-step method to optimize the nanoporous characteristics of TiO2 samples thus enabling a higher charge and discharge capacity and a larger rate capability compared to dense TiO2 materials. We use a simple sol-gel process to fabricate spherical titanium glycolates precursors followed by subsequent hydrothermal or annealing treatments resulting, respectively, in highly porous or dense TiO2 nanospheres. These processes enable control of the grain size, pore structure, and specific surface area of the TiO2. The fabricated TiO2 nanostructures have been subsequently used to assemble lithium-ion batteries. Galvanostatic discharge-charge tests indicate that the porous TiO2 nanospheres possess high and stable reversible capacity of 229, 133, and 56 mAh g(-1) at 0.06, 0.6 and 6C, respectively; whereas the corresponding values for dense TiO2 nanospheres are 217, 45, and similar to 1 mAh g(-1). Such considerable improvement of the electrochemical activity is attributed to the porous TiO2 nanostructures, and subsequent change in diffusion length, and enables the possibility to optimize the high rate capability in TiO2-based lithium-ion batteries. (C) 2011 Elsevier B.V. All rights reserved.