The structural and electrochemical properties of LiCoO2 (LCO) cathode films grown at 500 degrees C and Li0.5La0.5TiO3 (LLTO) solid electrolyte films at room temperature by pulsed laser deposition were investigated by a rapid-thermal annealing (RTA) treatment. The LCO films annealed for 1 min at 700 degrees C showed the most superior crystallinity and the LLTO films grown on LCO at room temperature maintained an amorphous phase after RTA treatment for 5 min up to 700 degrees C. The highest initial discharge capacity and capacity retention were obtained in Li/LiCoO2 cells annealed for 1 min at 700 degrees C. The RTA treatment is effective in improvement of an interface property and surface morphology of the LLTO films grown at room temperature on LCO. The LCO/pt cells exhibit an initial discharge capacity of approximately 53 mu A h cm(-2) gm and a capacity retention of 73% at 100 cycles. The LLTO/LCO/Pt cells treated at 700 degrees C for 5 min in an oxygen ambient by RTA exhibited an improvement of a capacity retention as high as 96.1% at 100 cycles. (c) 2005 American Vacuum Society.