Fabrication of LiCoO₂ thin films by sol-gel method and characterisation as positive electrodes for Li/LiCoO₂ cells

LiCoO₂ thin films are receiving attention as positive electrodes (cathodes) for thin-film microbatteries. In this study, LiCoO₂ thin films are fabricated by a sol-gel spin-coating method and a post-annealing process. The thermal decomposition behaviour of the precursor is investigated by thermogravimetry/differential thermal analysis TG/DTA and mass spectroscopy. The crystallinity, microstructure and electrochemical properties of the final films are also studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge-discharge cycling tests. Films heat-treated under appropriate conditions exhibit high capacity and good crystallinity and are therefore considered to be candidates as cathodes for thin-film microbatteries.