We investigated the dependence of the various annealing conditions and thickness ( 6∼45nm ) of the Ti-doped Al 2 O 3 coating on the electrochemical properties and the capacity fading of Ti-doped Al 2 O 3 coated LiCoO 2 films. The Ti-doped- Al 2 O 3 -coating layer and the cathode films were deposited on Al 2 O 3 plate substrates by RF-magnetron sputter. Microstructural and electrochemical properties of Ti-doped- Al 2 O 3 -coated LiCoO 2 films were investigated by transmission electron microscopy (TEM) and a dc four-point probe method, respectively. The cycling performance of Ti-doped Al 2 O 3 coated LiCoO 2 film was improved at higher cut-off voltage. But it has different electrochemical properties with various annealing conditions. They were related on the microstructure, surface morphology and the interface condition. Suppression of Li-ion migration is dominant at the coating thickness >24.nm during charge/discharge processes. It is due to the electrochemically passive nature of the Ti-doped Al 2 O 3 films. The sample be made up of Ti-doped Al 2 O 3 coated on annealed LiCoO 2 film with additional annealing at 400 ? C had good adhesion between coating layer and cathode films. This sample showed the best capacity retention of ∼92 with a charge cut off of 4.5 V after 50 cycles. The Ti-doped Al 2 O 3 film was an amorphous phase and it has a higher electrical conductivity than that of the Al 2 O 3 film. Therefore, the Ti-doped Al 2 O 3 coated improved the cycle performance and the capacity retention at high voltage (4.5 V) of LiCoO 2 films.