The structure and electrochemical performance of Na+-, K+-, and Ca2+-vanadium oxide nanotubes

Vanadium oxide (VOx) nanotubes, with embedded Na+-, K+-, or Ca2+-ions, were synthesized and investigated structurally and electrochemically in a Li-battery context. The nanotubes consist of scroll-like layers of vanadium oxide separated by structure-directing primary amines or metal cations. X-ray diffraction and Raman spectroscopy provided structural information of the VOx sheets. It was found that the structure within the layers is similar to the double-layered BaV7O16.nH(2)O. Galvanostatic measurements showed that the materials cycle reversibly for >100 cycles, giving average capacities of around 150 mAh/g(1.8-3.5 V vs. Li/Li+). (C) 2003 The Electrochemical Society.