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

• TiO2 nanotubes (NTs) are grown onto a Ti foil by ultra-fast anodic oxidation.
• NTs exhibit noticeable stability and capacity retention after prolonged cycling.
• NTs show improved durability (>1100 cycles) at a very high C-rate.
• Short diffusion path and fast kinetics are responsible for superior performance.
• TiO2 NTs are interesting candidate for next generation micro Li-based cells.

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/morphological characterization 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.

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