Electrochemical and structural properties of V2O5 thin films prepared by direct current sputtering

Vanadium pentoxide thin films have been prepared by reactive direct current magnetron sputtering from a vanadium metal target without annealing posttreatment. XRD, Raman and electrochemical experiments on 800 nm thin films have shown a high degree of crystallinity of the deposits. Chronopotentiometric measurements performed in two voltage range 3.8-2.8 V and 3.8-2.15 V have demonstrated the promoting effect of the hOO preferred orientation of V 2 O 5 films in terms of polarization, kinetics and rate capability. The same reproducible deposition method is successfully applied to obtain films thicker than 1 μm in order to optimize the specific capacity. Effective high specific capacities can then be obtained with films 2.4 μm thick, tested at a high constant current density (100 μAh.cm - 2 ): a stable capacity of 75 μAh.cm - 2 is available over 100 cycles in the 3.8/2.8 V potential range and 130 μAh.cm - 2 are still recovered in the range 3.8/2.15 V. These results indicate that a promising cycling behaviour can be expected with thick films exhibiting a preferred orientation corresponding to V 2 O 5 planes perpendicular to the substrate.