Amorphous Vanadium Oxide Thin Films As Stable Performing Cathodes of Lithium and Sodium-Ion Batteries

Herein, we report additive- and binder-free pristine amorphous vanadium oxide (a-VOx) for Li- and Na-ion battery application. Thin films of a-VOx with a thickness of about 650 nm are grown onto stainless steel substrate from crystalline VO target using pulsed laser deposition (PLD) technique. Under varying oxygen partial pressure (pO) environment of 0, 6, 13 and 30 Pa, films bear O/V atomic ratios 0.76, 2.13, 2.25 and 2.0, respectively. The films deposited at 6‑30 Pa have a more atomic percentage of V than that of V with a tendency of later state increased as pO rises. Amorphous VOx films obtained at moderate pO levels are found superior to other counterparts for cathode application in Li- and Na-ion batteries with reversible capacities as high as 300 and 164 mAh g at 0.1 C current rate, respectively. At the end of the 100th cycle, 90% capacity retention is noticed in both cases. The observed cycling trend suggests that more is the (V) stoichiometric nature of a-VOx better is the electrochemistry.