THIN-FILM LI-LIMN2O4 BATTERIES

Thin-film rechargeable Li-LiMn2O4 batteries have been fabricated and characterized. Following deposition by electron beam evaporation of LiMn2O4, the amorphous as-deposited cathode films 1 cm(2) in area by 0.3- to 4-mu m thick were annealed at 700 degrees C to 800 degrees C in oxygen in order to form the crystalline spinet phase. The specific capacity of the cells between 4.5 V to 3.8 V ranged from 50 mu Ah/mg to 120 mu Ah/mg. When cycled over this range, the batteries exhibited excellent secondary performance with capacity losses as low as 0.001% per cycle. On charging to 5.3 V, a plateau with a median voltage of 5.1 V was observed. The total charge extracted between 3.8 V to 5.3 V corresponded to about 1 Li/Mn2O4.