LOW-TEMPERATURE LIMN2O4 SPINEL FILMS FOR SECONDARY LITHIUM BATTERIES

Low temperature thin film LixMn2O4 spinel, with x congruent-to 1, are fabricated for use in secondary batteries. The spinel crystal structure is obtained by in situ postdeposition annealing of the films at temperatures as low as 400-degrees-C. Such temperatures are compatible with semiconductor processing, permitting future integration of the batteries with electronics. 1-3-mu-m thin LiMn2O4 films are tested in LiMn2O4/EC + DEE + LiClO4/Li arrangements. They intercalate nearly one Li+ ion at an average potential of 4.1 V and show very good intercalation kinetics, so that a 10 C discharge rate produces an energy density of 500 W-h per kilogram of active cathode material. These LiMn2O4 filMS show very promising cycle life, even at 55-degrees-C. Films cycled more than 220 times maintain more than 70% of their original capacity.