New electrolyte materials, polymers or inorganic glasses, allow the design of flat lithium primary or secondary batteries for miniaturised devices from smart cards to CMOS back up. The so-called "hybrid plastic electrolytes" allow the design of thick film cells (1 - 3 mm) with a surface capacity of some mA h cm(-2). For Li-ion secondary batteries, the number of cycles does not currently exceed 500. All solid state thin film batteries are manufactured using sputtering and vacuum evaporation techniques. Their thickness and surface capacity are about one order of magnitude lower than for the polymer electrolyte batteries. In spite of metallic Li anodes, they offer a better cyclability and the solid state of all components guaranties no liquid leakage.