Fabrication of LiCoO2 thin film cathodes by DC magnetron sputtering method

Abstract

LiCoO2 thin films were fabricated on Al substrate by direct current magnetron sputtering method. The effects of Ar/O-2 gas rates and annealing temperatures were investigated. Crystal structures and surface morphologies of the deposited films were investigated by X-ray diffraction, Raman scattering spectroscopy and field emission scanning electron microscopy. The as-deposited LiCoO2 thin films exhibited amorphous structure. The crystallization starts at the annealing temperature over 400 degrees C. However, the annealed films have the partially disordered structure without completely ordered crystalline structure even at 600 degrees C annealing. The electrochemical properties of the LiCoO2 films were investigated by the charge-discharge and cycle measurements. The 500 degrees C annealing film has the highest capacity retention rate of 78.2% at 100th cycles. (C) 2012 Elsevier Ltd. All rights reserved.