Abstract
The increasing demand for portable energy has generated significant research interest in nanostructured electrode materials, because of their large interfacial contact area with the electrolyte and short path lengths for Li ion transport. To date, titanium dioxide (TiO~2~) has been widely investigated as an electroactive, Li‐insertion host. However, the lithium reactivity of brookite‐type TiO~2~ has rarely been addressed compared to the common polymorphs, anatase and rutile, because of the difficulties encountered in obtaining a phase‐pure brookite structure. Herein, we report on the simple synthesis of nanocrystalline brookite‐type TiO~2~ using titanium trichloride (TiCl~3~) and urea [(NH~2~)~2~CO]. The average size of the particles precipitated at 100 °C was ca. 10 nm. The brookite structure was stable up to 500 °C and was completely transformed to the rutile structure at 900 °C in an O~2~ atmosphere. We evaluated the electrochemical properties of each TiO~2~ powder heat‐treated sample at a preset temperature. Hybrid carbon/TiO~2~ nanocomposites with high conductivity were also fabricated using a stable suspension of multi‐walled carbon nanotubes (MWCNTs) in aqueous suspension with an appropriate surfactant and subsequent precipitation of TiO~2~. The carbon incorporation clearly improved the capacity retention of TiO~2~ upon cycling.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)