Growth, micro structural and electrochemical properties of RF magnetron sputter deposited LiCoO2

Authors : P. Jeevan Kumara , K. Jayanth Babub and O. M. Hussam

Abstract

Thin films of LiCoO2 are prepared by rf magnetron sputtering technique using a sintered 3″ high dense target. The influence of oxygen to argon gas composition on the growth, microstructural and electrochemical properties of LiCoO2 thin films are systematically investigated. The films deposited at higher oxygen to argon ratio are found to be lithium deficient with LT-LixCo304 crystalline phase. With the decrease of oxygen to argon ratio the crystallographic structure of the film has been transformed to HT-LiCo02 symmetry. The films deposited at lower oxygen to argon ratio of 1:9 with subsequent annealing at 923 K in a controlled oxygen atmosphere are found to be polycrystalline with predominant (1 0 4) orientation representing HT-LiCo02 layered structure with Ram crystalline space group. The microstructural features of the films are supported by the Raman and Scanning electron microscope (SEM) results. These films exhibited better electrochemical performance with a discharge capacity of
60 [tAh.cm 2.1.tm-1 and are useful as binder free positive electrodes

Keywords : Lithium cobalt oxide, Microstructure, Electrochemical properties, Thin film cathodes.