ALD AlO-Coated TiO Nanotube Layers as Anodes for Lithium-Ion Batteries.

The utilization of the anodic TiO nanotube layers, with uniform AlO coatings of different thicknesses (prepared by atomic layer deposition, ALD), as the new electrode material for lithium-ion batteries (LIBs), is reported herein. Electrodes with very thin AlO coatings (∼1 nm) show a superior electrochemical performance for use in LIBs compared to that of the uncoated TiO nanotube layers. A more than 2 times higher areal capacity is received on these coated TiO nanotube layers (∼75 vs 200 μAh/cm) as well as higher rate capability and coulombic efficiency of the charging and discharging reactions. Reasons for this can be attributed to an increased mechanical stability of the TiO nanotube layers upon AlO coating, as well as to an enhanced diffusion of the Li ions within the coated nanotube layers. In contrast, thicker ALD AlO coatings result in a blocking of the electrode surface and therefore an areal capacity decrease.