Thin films of LiCoO2 prepared by the electron cyclotron resonance (ECR) sputtering method are investigated under various deposition conditions. Well-crystallized LiCoO2 films were obtained without a post-annealing process in a high microwave and RF power range with a low O-2 to Ar ratio. All-solid-state thin-film lithium batteries using the LiCoO2 films (thickness: 6.2 mu m) provided a discharge capacity of about 250 mu Ah cm(-2) with good cyclability. (c) 2007 Elsevier B.V. All rights reserved.