Abstract: Electrochemical energy cells are disclosed. The energy cells are basically reserve-type batteries in which the electrolyte is separated from the electrodes until the battery is ready for use. In a first embodiment, the battery is a cylindrical battery in which the electrolyte is stored in a frangible envelope inside the battery case and above the electrode structure. Means are provided to break the envelope holding the electrolyte to permit the electrolyte to flow into the electrode cavity. The anode and cathode are designed to permit free flow of the electrolyte. In a second embodiment, the battery is also cylindrically shaped but is formed in a very thin or short cylinder. In this second embodiment the electrolyte is stored in a frangible envelope in the center of the battery casing. Again, means are provided to break the frangible envelope so that the electrolyte can flow into the electrode cavity and activate the battery.