Precursor derived LiMn2O4 thin films as ionic conductor

Abstract

Thin films of spinel LiMn2O4 have been fabricated using a metallorganic precursor. Crystalline films have been deposited on Au substrates to exhibit as the cathode in rechargeable thin film lithium batteries. The nucleation and growth of spinel LiMn2O4 crystallites were investigated with heat treatment of the deposited thin films. Film capacity density as high as 22 µAh/cm2 was measured for LiMn2O4. The film heat treated at 700 °C were cycled electrochemically up to 30 cycles against Li metal without any degradation of the capacity. There were neither open area nor amorphous layers which prevent the Li+ions transfer at the boundaries in the LiMn2O4 thin film. The microscopic study revealed that (111) planes in the two grains directly bonded at the grain boundary which could proceed the lithium ion intercalation or deintercalation smoothly.