We have investigated the effect of the protective Ta2O5 thin films on the electrochemical behaviors of test cells fabricated with SnO2 electrodes. It is shown that for the cells made with the single SnO2 electrodes, their cycling performance is rapidly degraded with increasing cycle number. However, the addition of the Ta2O5 thin film on the SnO2 electrodes results in a slow degradation of capacity. The improved
electrochemical behaviors of the cells made with the Ta2O5 film-coated SnO2 electrodes are attributed to the combined roles that the Ta2O5 films serve as a protective layer and facilitate the passage of Li ions during cycling.
Keywords : Thin film batteries; Protective layer; Ta2O5; SnO2 electrode; Sputtering