Abstract: A bipolar compression cell for a water-activated battery that can be used with a plurality of such cells stacked together in a side-by-side array to form the bipolar battery. Each cell includes an elastomeric frame that can be compressed and a special alloy foil that separates cuprous iodide and magnesium elements and which does not interact with the cuprous iodide or magnesium to allow for bipolar action when the cells are stacked side-by-side. The use of elastomeric frames allows for low cost manufacture, eliminating manual construction. The water-activated battery is especially useful in sonobuoys.