The Li/electrolyte interface of Li/LiMn2O4 plastic batteries was characterized during galvanostatic cycling by means of impedance spectroscopy. The impedance diagrams acquired during the charge and discharge of the battery were modeled and interpreted, in order to determine the lithium plating/stripping processes on the Li degrees -electrode. By means of known Li degrees /electrolyte interface models, a mechanism was then proposed by considering the passivation film and charge transfer effects. These results were also confirmed by three-electrode measurements. (C) 2000 Elsevier Science B.V. All rights reserved.