Microfabrication of LiCoO2 film using liquid source misted chemical deposition technique

The process called “liquid source misted chemical deposition” was used to prepare lithiated cobalt oxide film as a cathode for lithium rechargeable microbatteries. In this research, the effects of different solvents and heat treatments on the film properties were investigated. The precursor solution was a 0.2-M solution of LiNO3 and Co(NO3)2·6H2O in 2-methoxyethanol and ethylene glycol, and was atomized using an ultrasonic nebulizer during the process. When the heat treatment of as-deposited films on Pt/SiO2/Si substrate for crystallization was carried out at 800 °C in rapid thermal apparatus (RTA) in the oxygen atmosphere for 5 min, the structural and compositional purity of the deposited film as well as its electrochemical activity were optimized. The prepared LiCoO2 film exhibits the initial discharge capacity of 57.1 μA h/cm2·μm. Because the cells cycled between 3.0 and 4.0 V and between 3.0 and 4.2 V show the capacity fade over 100 cycles of 43.1% and 52.1%, it is found that the capacity fade is partially ascribed to the phase transitions around 4.1 and 4.2 V as shown in the cyclic voltammogram.