Improvement in electrochemical performance of V₂O₅ by Cu doping

Cu_0.04V₂O₅ was prepared by a precipitation method followed by heat treatment at 300 and 600 °C. The material prepared at 300 °C showed porous morphology, whereas that prepared at 600 °C was highly crystalline. X-ray diffraction, Raman scattering and Fourier transform infrared spectroscopy showed both materials exhibiting the same structure as that of V₂O₅, with a slight lattice expansion. X-ray absorption spectroscopy confirmed the presence of V⁴⁺ cations in Cu_0.04V₂O₅, which would increase the electronic conductivity of V₂O₅. Cu_0.04V₂O₅ showed better electrochemical performance than V₂O₅ because of its high electronic conductivity and good structural stability. The material prepared at 600 °C delivered a reversible discharge capacity over 160 mAh g^-1 after 60 cycles at a C rate of C/5.6. The material prepared at 300 °C showed good high-rate performance, which delivered a reversible capacity ∼100 mAh g^-1 when cycled at C/1.9. The discrepancy in the rate performance of Cu_0.04V₂O₅ was attributed to the morphology of materials.