Electrochemical properties of freestanding TiO2 nanotube membranes annealed in Ar for lithium anode material

Freestanding and highly ordered TiO₂ nanotube membranes were prepared via anodization and annealed at 450, 600, and 800 °C in air and Ar, respectively. Based on the results of XRD and SEM, the membranes annealed in Ar and air possessed different morphology and crystalline phases. Compared with the sample annealed in air, a trace amount of carbon on TiO₂ membrane annealed in Ar was detected by EDS spectrum. Electrochemical measurements showed that TiO₂ membrane annealed in Ar exhibited better discharge capacity and cyclic stability. The noticeably improved electrochemical performances were attributed to the presence of carbon which enhanced the surface electronic conductivity, the crystalline transformation, and the appropriate morphology, such as large pore, thin wall, and well tube structure.