Vertically aligned TiO2 nanotube array for high rate Li-based micro-battery anodes with improved durability

Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, thus easily up-scalable, anodic oxidation of a titanium foil followed by rapid thermal annealing. The structural/morphologicalcharacterization shows the formation of well defined one-dimensional nanotube carpets, while the X-ray diffraction analysis reveals the pure anatase crystalline structure of the thermal treated samples. The electrochemical response in laboratory-scale lithium cells is highly satisfying: at a very high discharge/charge rate of 12C, the NTs can perform with good stability and capacity retention after long-term cycling along with improved durability (>1100 cycles). High surface area, self-induced doping, short diffusion path and fast kinetics of the unidirectionally aligned TiO2 nanotube arrays are intriguing prospects which can be considered responsible for the noticeable electrochemical performance obtained in the absence of foreign ingredients such as binders and conductive agents, which would affect the overall energy density.