Electrochemical properties of spherically shaped dense V ₂O ₅ cathode powders prepared directly by spray pyrolysis

Spherically shaped vanadium pentoxide (V ₂O ₅) cathode powders with porous or dense morphologies are prepared directly via spray pyrolysis by varying the preparation temperatures between 600 and 1000 °C. The powders prepared at 600 °C consist of nanometer-sized rod-shaped crystals with porous structures. The V ₂O ₅ powders prepared at 1000 °C have spherical shapes, clean surfaces, and dense structures, because of complete melting of the powders that occurs inside the hot-wall reactor. The Brunauer-Emmett-Teller (BET) surface areas of the V ₂O ₅ powders decrease from 24.7 to 3.2 m ² g ^-1 when the preparation temperature increases from 600 to 1000 °C. The V ₂O ₅ powders prepared at 1000 °C have better cycle properties than those prepared at 600 and 800 °C. The discharge capacity of the V ₂O ₅ powders prepared at 1000 °C decreases from 432 mAh g ^-1 to 263 mAh g ^-1 after 20 cycles, in which the capacity retention is 61%.