ALD Al₂O₃-Coated TiO₂ Nanotube Layers as Anodes for Lithium-Ion Batteries

摘要

The utilization of the anodic TiO_(2) nanotube layers, with uniform Al_(2)O_(3) 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 Al_(2)O_(3) coatings (～1 nm) show a superior electrochemical performance for use in LIBs compared to that of the uncoated TiO_(2) nanotube layers. A more than 2 times higher areal capacity is received on these coated TiO_(2) nanotube layers (～75 vs 200 μAh/cm~(2)) 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_(2) nanotube layers upon Al_(2)O_(3) coating, as well as to an enhanced diffusion of the Li~(+) ions within the coated nanotube layers. In contrast, thicker ALD Al_(2)O_(3) coatings result in a blocking of the electrode surface and therefore an areal capacity decrease.