Electrochemical and structural properties of V_2O_5 thin films prepared by DC sputtering

摘要

Vanadium pentoxide thin films have been prepared by reactive DC magnetron sputtering from a vanadium metal target without annealing posttreatment. XRD, Raman and electrochemical experiments on 800 nm thin films show a high crystallinity of the deposits. Chronopotentiometric measurements performed in the two voltage range 3.8-2.8 and 3.8-2.15V have demonstrated the promoting effect of the h 0 0 preferred orientation of V_2O_5 films in terms of polarization, kinetics and rate capability. The same reproducible deposition method is successfully applied to get films thicker than 1 mu m in order to optimize the specific capacity. Effective high specific capacities can be then obtained with films 2.4 mu m thick tested at high constant current density (100 mu A cm~(-2)): a stable capacity of 75 mu A cm~(-2) is available over 100 cycles in the 3.8-2.8 V potential range and 130 mu Ah cm~(-2) are still recovered in the range 3.8-2.15 V. These results indicate a promising cycling behaviour can be expected with thick films exhibiting a preferred orientation corresponding to V_2O_5 planes perpendicular to the substrate.