Layered hydrogen titanate nanowires with novel lithium intercalation properties

Layered hydrogen titanate nanowires were synthesized from TiO2 via an alkaline-hydrothermal process and subsequent acid treatment. The average diameter of as-prepared nanowires is about 100 nm with a uniform interlayer spacing of 0.81 nm. The framework of this hydrogen titanate nanowires holds the composition of H2Ti3O7 as determined by thermogravimetric analysis. The nanostructured electrode made from these nanowires shows large lithium intercalation capacity (reversible lithium intercalation with Li0.71H2/3TiO7/3), high discharge/charge rate capability, and excellent cycling stability, as revealed by galvanostatically charge/discharge cycling tests. The detailed cyclic voltammetric investigation, however, indicates that the hydrogen titanate nanowires show pseudocapacitive characteristic during the Li+ insertion process. The novel electrochemical properties of hydrogen titanate nanowires are attributed to the open layered structure with a much larger interlayer spacing than normal intercalation compounds for commercial lithium ion batteries. The layered hydrogen titanate nanowires with unique electrochemical performance may become a promising lithium intercalation material for high-energy rechargeable lithium ion batteries and electrochemical supercapacitors.