Layered Hydrogen Titanate Nanowires with Novel Lithium Intercalation Properties

Layered hydrogen titanate nanowires were synthesized from TiO 2 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 H 2 Ti 3 O 7 as determined by thermogravimetric analysis. The nanostructured electrode made from these nanowires shows large lithium intercalation capacity (reversible lithium intercalation with Li 0.71 H 2/3 TiO 7/3 ), 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.