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

摘要

A vanadium pentoxide (V_2O_5) 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 V_2O_5 film is amorphous. The crystallinity increases with rise in the annealing temperature from 200 to 275℃ and is composed of orthorhombic V_2O_5 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 1 M LiClO_4/propylene carbonate (PC) as electrolyte. Good cycleability and high capacity (270 mAh g~(-1)) is achieved at a current rate of 0.2C by annealing the thin-film at 275℃. Furthermore, the capacity remains stable even after 25 cycles; excellent capacity retention is observed even at the 1C rate (260 mAh g~(-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.