A lithium microbattery comprises a substrate on which at least one stack is arranged successively comprising a cathode, an electrolyte containing lithium and an anode consisting of metallic lithium. A protective envelope comprising at least first and second distinct superposed layers covers the stack to protect the same against external contamination. The first layer, deposited on the whole of the anode, comprises at least one material that is chemically inert with regard to lithium, selected from the group consisting of a hydrogenated amorphous silicon carbide, a hydrogenated amorphous silicon oxycarbide, hydrogenated amorphous carbon, fluorinated amorphous carbon and hydrogenated amorphous silicon. The second layer comprises a material selected from the group consisting of a hydrogenated amorphous silicon carbonitride, a hydrogenated amorphous silicon nitride and a fluorinated amorphous carbon.