We introduced a post-annealing process for the preparation of spinel-phase LiMn2O4. The annealed films had proper crystallinity and surface roughness. In order to reduce the interface reaction during operation, we introduced a diamond-like carbon (DLC) film. The DLC films were deposited on LiMn2O4 films by using electron cyclotron resonance chemical vapor deposition (ECRCVD). A DLC-coated LiMn2O4 film was more stable during the charging-discharging reaction and showed higher discharge capacity over a wide voltage window than the uncoated LiMn2O4 film. (C) 2003 Elsevier Science B.V. All rights reserved.