Sputtered Al-doped lithium manganese oxide films for the cathode of lithium ion battery: The post-deposition annealing temperature effect

In this paper, lithium-excess Al-doped lithium manganese oxide films were prepared by R.F. magnetron sputtering at ambient temperature. X-ray diffraction, scanning electron microscopy, Raman spectra and constant current charge/discharge cycling were employed to study the post-deposition annealing effect. It has been found that the annealing temperature threshold for a single spinel phase was about 600 degrees C in oxygen atmosphere. The films annealed at 500 degrees C showed a composite structure with fine particles, which resulted in good capacity retention capability in both 4 V and 3 V regions. When annealed at 700 degrees C, a lithium deficient phase appeared, which led to structure reorganization and reduced adhesion of the cathode films to underlying Pt films, which caused poorer capacity retention capability. (C) 2009 Elsevier B.V. All rights reserved.