Pulsed laser deposition and characterization of crystalline lithium cobalt dioxide, (LiCoO2) thin films

The pulsed laser deposition of LiCoO2 and LiCo0.5Al0.5O2 thin films was investigated as a function of deposition conditions. The initial growth process optimization focused on films grown on (200)-textured SnO2-coated glass substrates. Film growth was also investigated on ZnO and indium-tin oxide (ITO) coated substrates. For both LiCoO2 and LiCo0.5Al0.5O2, dense uniaxially textured (003)-oriented films of the layered LiCoO2 phase were grown on the SnO2 coated substrates. The grain size increased substantially with increased substrate temperature in the range from 400 to 700 degreesC. For constant current cycling between 3.5 and 4.4 V vs. Li, the best crystalline LiCoO2 films, grown at T-s = 700 degreesC, p(O2) = 2000 mTorr, had an initial discharge capacity of similar to 118 mAh/g (0.43 Li/Co) which decreased similar to0.5% per cycle. For LiCo0.5Al0.5O2, although, as predicted, the films did have a higher cathode potential, the charge capacity was significantly lower than that for LiCoO2 films. Finally, functional LiCoO2 thin film cathodes were grown on flexible ITO-coated Upilex polymer substrates at T-s = 300 degreesC. (C) 2001 The Electrochemical Society.