Effect of La Doping on the Structure and Lithium Storage Performance of V₂O5.

Abstract

La-doped vanadium pentoxide (V₂O5) was prepared by sol-gel method and subsequent heat treatment in air at 400 °C. The influence of La-doping on the crystalline structure, surface morphology, and lithium storage performance of V₂O5 were investigated by XRD, SEM, CV, EIS, and discharge-charge tests. The results demonstrated that La doping did not change the phase structure of orthorhombic V₂O5, but significantly refined the crystal grain of V₂O5; La doping obviously improved the cycling stability and rate capability of V₂O5 due to the decreased electrode polarization, smaller electron-transfer resistance, and enhanced lithium diffusivity. For example, the La-doped V₂O5 delivered a reversible capacity of 131 mAh/g after 50 cycles at a current density of 200 mA/g, while the pure V₂O5 showed a reversible capacity of only 63 mAh/g under the same condition. At the high rate of 500 mA/g, the La-doped V₂O5 still displayed a reversible capacity of 106 mAh/g, which is two times higher than that (45 mAh/g) of pure V₂O5 sample.