Electrochemical stability in cerium-phosphate-coated LioO2 thin films

The electrochemical stability of LiCoO2 thin films was improved by cerium-phosphate coating deposited at room temperature. The cerium-phosphate coating layer also effectively suppressed the increase of charge-transfer resistance during cycling. However, the cycling stability and the initial capacity of the coated LiCoO2 thin films deteriorated as the annealing temperature increased, different from other metal-phosphate coating. These phenomena were attributed to the interdiffusion between the cerium-phosphate coating, layer and LiCoO2, thin film, instead of the nanocrystal formation in the amorphous coating layer.