Nanoscale size effect of titania (anatase) nanotubes with uniform wall thickness as high performance anode for lithium-ion secondary battery

We report the synthesis of titania (TiO2) nanotubes (NTs) with precisely controlled wall thickness by atomic layer deposition (ALD) using alumina membranes as template and their application as anode material for lithium (Li) ion storage in secondary battery. As-grown nanotubes are amorphous in nature and transform into anatase phase by subsequent thermal annealing. The charge/discharge capacities and rate performance are found to be dependent on the wall thickness, which is highly uniform, of the NTs. Maximum reversible capacity for Li-insertion in anatase TiO2∼330mAhg−1 has been achieved by reducing the tube wall thickness to 5nm. NTs with the wall thickness of 40nm show reversible capacity of ∼170mAhg−1 which is similar to the maximum theoretical capacity of the bulk anatase as reported. With decrease in the wall thickness, rate performance of the NTs is significantly improved. NTs with 5nm in the wall thickness render excellent rate capability and cycle response.