Electrochemical performance of mixed crystallographic phase nanotubes and nanosheets of titania and titania-carbon/silver composites for lithium-ion batteries

The role of homogeneity in ex situ grown conductive coatings and dimensionality in the lithium storage properties of TiO2 is discussed here. TiO2 nanotube and nanosheet comprising of mixed crystallographic phases of anatase and TiO2 (B) have been synthesized by an optimized hydrothermal method. Surface modifications of TiO2 nanotube are realized via coating the nanotube with Ag nanoparticles and amorphous carbon. The first discharge cycle capacity (at current rate = 10 mA g(-1)) for TiO2 nanotube and nanosheet were 355 mAh g(-1) and 225 mAhg(-1), respectively. The conductive surface coating stabilized the titania crystallographic structure during lithium insertion-deinsertion processes via reduction in the accessibility of lithium ions to the trapping sites. The irreversible capacity is beneficially minimized from 110 mAh g(-1) for TiO2 nanotubes to 96 mAh g(-1) and 57 mAhg(-1) respectively for Ag and carbon modified TiO2 nanotubes. The homogeneously coated amorphous carbon over TiO2 renders better lithium battery performance than randomly distributed Ag nanoparticles coated TiO2 due to efficient hopping of electrons. (C) 2011 Elsevier B.V. All rights reserved.