Energy storage studies of bare and doped vanadium pentoxide, (V1.95M0.05)O5, M = Nb, Ta, for lithium ion batteries

Abstract

The bare V₂O₅ and doped (V_1.95M_0.05)O₅ (M = Nb, Ta) nano/submicron sized compounds were prepared by the simple polymer precursor method. The compounds were characterized by different physical and electroanalytical techniques. The effects of doping and different synthesis conditions on the energy storage performance of the V₂O₅ compounds were discussed. All compounds delivered a discharge capacity (at the end of the 2^nd cycle) in the range 245 to 261 (±3) mA h g⁻¹, except for the tantalum doped compound (V_1.95Ta_0.05)O₅ which exhibited a discharge capacity of 210 (±3) mA h g⁻¹, cycled in the range 2.0–4.0 V at a current rate of 120 mA g⁻¹. An excellent cycling stability of 96% till twenty cycles was achieved for the compound V₂O₅ prepared by the polymer precursor method. Electrochemical impedance spectroscopy studies at different voltages during discharge and charge cycles were discussed in detail.