Physical Vapor Deposition Preparation Of All Solid-state Thin Film Lithium-ion Battery Cathode Material Of Licoo <sub> 2 </ Sub>,

Because of the development of electronic device and Micro-Electronic Mechanical Systems (MEMS) technology, energy system composed of common size batteries may have a lot of problems. Lithium ion thin film micro-batteries have received much attention due to their potential application as backup power in MEMS, smart card micro-sensors and biochips. The performance of the Lithium ion thin film micro-batteries is basically determined by the electrode materials. Hence, the cathode material becomes the most critical factor of improving the electrochemical properties of Lithium ion thin film micro-batteries.Although LiCoO2 has been studied and commercialized for a long time, it is not well known as the cathode of all solid lithium ion film batteries. In this thesis, LiCoO2 films have been deposited on the different substrate by Pulse Laser Deposition (PLD) and Radio Frequency (RF) sputtering, where the structures and electrochemical properties have been studied. We have finally obtained well crystalline LiCoO2 film which has well-defined and close-packed particle.In order to obtain well crystalized LiCoO2 film which has preferred orientation, we pay attention to optimize the process parameters of RF and PLD. Results are as follows: As for PLD method, the film on Si has (003) preferred orientation, film on Au which has (104) preferred orientation and film on SS (Stainless steel) which has random orientation.On the other hand, the film on Si deposited by RF shows rather weak (003) preferred orientation. Furthermore, the film on the Au substrate demonstrates very strong (104) preferred orientation due to the inductive effect of the Au substrate. In a sentence, the film deposited by the RF is a-axis oriented, and the film by PLD prefers c-axis orientation.All electrochemical measurements including Galvanstatic charge-discharge cycling test and CV test were carried out on the Li//LiCoO2 cell assembled in beakers in the glove box. Galvanstatic charge-discharge cycling test was done between 3 and 4.2V at a constant current density. The initial discharge specific capacity of the film obtained by PLD on SS substrate which has random orientation reached 111.9mAh/g (81.7% of the theoretical capacity). During the 10 charge-discharge cycles, the capacity fade was around 1.80% per cycle. The initial discharge specific capacity of the film obtained by RF on Al substrate which has (003)-(104) orientation reached 128.5mAh/g (93.8% of the theoretical capacity). During the 10 charge-discharge cycles, the capacity fade was around 3.50% per cycle.