Performance of electrostatic spray-deposited vanadium pentoxide in lithium secondary cells

A vanadium pentoxide (V₂O₅) thin-film is deposited on to a platinum substrate using an electrostatic spray deposition (ESD) technique and its performance in a secondary lithium cell is reported for the first time. The deposited thin-film is characterized in terms of structure and surface morphology using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD studies reveals that the structure of the thin V₂O₅ film is amorphous. The crystallinity increases with rise in the annealing temperature from 200 to 275 °C and is composed of orthorhombic V₂O₅ crystals. Scanning electron micrographs indicate the near-porous nature of the annealed thin-film. The electrochemical behavior of the thin-film of vanadate is investigated by means of cyclic voltammetry (CV) and galvanostatic discharge-charge cycling using a lithium metal anode in the voltage range 2.0-4.0 V (versus Li metal) in 1M LiClO₄/propylene carbonate (PC) as electrolyte. Good cycleability and high capacity (270 mAhg^-1) is achieved at a current rate of 0.2 C by annealing the thin-film at 275 °C. Furthermore, the capacity remains stable even after 25 cycles; excellent capacity retention is observed even at the 1 C rate (260 mAhg^-1). It is concluded that ESD is an excellent and cheap technique for fabricating thin-films of vanadate for use as cathodes in secondary lithium cells.