Li1−xNaxV3O8 as positive materials for secondary lithium batteries

Abstract

A series of Li1−xNaxV3O8 (0<x<1) solid solution were investigated as positive materials for secondary lithium batteries. The materials were characterized by X-ray diffraction and infrared spectrum measurements, showing that pure phases of Li1−xNaxV3O8 were formed with the same monoclinic structure as LiV3O8. The electrochemical characteristics including charge–discharge characteristics were compared with those of LiV3O8 and NaV3O8, showing that the Li0.7Na0.3V3O8 electrode shows the best electrochemical performance among several Li1−xNaxV3O8; at a current density of 0.2mAcm−2, it gave a discharge capacity of 215mAhg−1-oxide which was about 80% of the theoretical discharge capacity. The cathode current loading test also showed that Li1−xNaxV3O8 has the advantage of both LiV3O8 and NaV3O8. Furthermore, the thermodynamics and kinetics of lithium intercalation into the oxide structure were also examined.