Characterization of thermally aged AlPO(4)-coated LiCoO(2 )thin films

The electrochemical properties and stability during storage of pristine and AlPO(4)-coated LiCoO(2 )thin films were characterized. The wide and smooth surface of the thin film electrode might provide an opportunity for one to observe surface reactions with an electrolyte. The rate capability and cyclic performance of the LiCoO(2 )thin film were enhanced by AlPO(4 )surface coating. Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface, it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C. In contrast, the surface of the pristine sample was severely damaged after storage.