A method is provided for making a flexible primary battery suitable for microelectronics applications, and more particularly, for use with self-contained self-powered portable devices (SSPD) such as RF-ID tags. The method generally employs photolithography and etching techniques to minimize the thicknesses of metal foils required in the structure of the battery, as well as packaging methods which yield a flexible and durable battery having a thickness of not more than about 0.5 millimeter, and preferably about 0.3 millimeter or less, and a relatively small size on the order of a few square centimeters in surface area.