Vanadium oxide nanotubes -: A new nanostructured redox-active material for the electrochemical insertion of lithium

Vanadium oxide nanotubes were prepared in a modified sol-gel reaction of vanadium oxide triisopropoxide conducted in the presence of the structurally directing hexadecylamine and followed by hydrothermal treatment. The tubes consist of concentric shells of highly crystalline vanadium oxide separated by alternating organic amine layers. The template molecules were removed without structural breakdown of the nanotubes by a combined ion-exchange reaction and extraction process. The vanadium oxide nanotubes are redox-active and can electrochemically insert lithium reversibly. A specific charge up to 180 mAh g-1 (with respect to the oxide) was measured for Li+ insertion into porous electrodes containing template-free nanotubes. The specific charge decreased during cycling, indicating a loss of electroactivity.