Fabrication of LiCoO2 thin films on flexible stainless steel substrate for lithium ion batteries

The LiCoO2 cathode coating on a flexible stainless steel has been successfully formed by using sol–gel process and spin-coating technique. The microstructures and electrochemical performance of this LiCoO2 cathode were characterized by using an X-ray diffractometer (XRD), a scanning electron microscope (SEM) and electrochemical methods. After annealing at ca. 500 °C, the results of XRD showed that the LiCoO2 gel was crystallized and the crystallized thin films show hexagonal phase with a space group R 3¯ m. When the annealing temperatures kept at 700 °C, the stainless steel substrate was oxidized and subsequently reacted with LiCoO2. Such a reaction also destabilized the structure of LiCoO2. The SEM observation indicated that the average grain size of films increased with increasing temperature and the thickness of spin-coated films is ca. 1–3 μm. The LiCoO2 thin films prepared from sol–gel process and spin-coating exhibit reversible electrochemical behavior of Li+ intercalation and de-intercalation reactions.