Large interlayer spacing vanadium oxide nanotubes as cathodes for high performance sodium ion batteries.

Sodium ion batteries (SIBs), as a potential alternative to Li-ion batteries (LIBs), have attracted great attention from researchers. Herein, large interlayer spacing ferric ion substituted vanadium oxide nanotubes (Fe-VNTs) are fabricated using dodecylamine as a template a facile hydrothermal treatment followed by a ferric ion substitution process. The distances between the adjacent layers of VNT, Fe-VNTs and orthorhombic VO are 2.7 nm, 1.2 nm and 0.44 nm, respectively. The larger interlamellar spacing results in faster Na diffusion reaction kinetics, and the insertion of ferric ion into vanadium oxide layers removes the organic templates between the vanadium oxide layers, leading to high conductivity and small electrochemical reaction resistance. Serving as the sodium ion battery cathode, Fe-VNTs display enhanced sodium storage performance over orthorhombic VO.