A novel type of Ge nanotube arrays for lithium storage material.

Amorphous Ge nanotubes, featured of a top-closed tubular structure, were synthesized directly on metallic current collector substrates via a template technique. Measurement of electrochemical cycling reveals that these nanotubes can deliver reversible capacities of -1300 mAh/g (81% of the theoretical capacity) at the current density of C/20 (1C = 1600 mAh/g) and retain -700 mAh/g at 2C with columbic efficiencies over 99%. Such performance is comparable to that of the recently reported Ge nanowire anodes grown directly on the metallic substrates by the chemical vapor deposition, indicating that the present Ge nanotubes are a type of anode materials with high capacity and good rate performance for lithium storage.