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

The pulsed laser deposition of LiCoO2 and LiCo0.5Al0.5O2 thin films was inv estigated as a function of deposition conditions. The initial growth proces s optimization focused on films grown on (200)-textured SnO2-coated glass s ubstrates. Film growth was also investigated on ZnO and indium-tin oxide (I TO) coated substrates. For both LiCoO2 and LiCo0.5Al0.5O2, dense uniaxially textured (003)-oriented films of the layered LiCoO2 phase were grown on th e SnO2 coated substrates. The grain size increased substantially with incre ased substrate temperature in the range from 400 to 700 degreesC. For const ant current cycling between 3.5 and 4.4 V vs. Li, the best crystalline LiCo O2 films, grown at T-s = 700 degreesC, p(O2) = 2000 mTorr, had an initial d ischarge capacity of similar to 118 mAh/g (0.43 Li/Co) which decreased simi lar 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 cat hodes were grown on flexible ITO-coated Upilex polymer substrates at T-s = 300 degreesC. (C) 2001 The Electrochemical Society.