This lithium electrochemical device includes a stack of layers suitable for constituting a micro-battery deposited on a substrate and encapsulated using a protective cap sealed onto the substrate. It includes two collectors of the current generated by the micro-battery and at least one insulating layer inert as regards lithium. The collectors and the insulating layer or layers are deposited on the substrate. The protective cap is sealed onto the substrate using the layers constituting the current collectors and the insulating layer or layers. The cap has layers of the same nature, positioned in the same order in line with their respective layers deposited on the substrate, so that when the cap is sealed onto the substrate, the respective layers deposited on the cap and on the substrate come into contact with each other to provide the actual seal of the cap on the substrate.