An energy storage device is provided that includes a separator having a first surface and a second surface. The first surface defines at least a portion of a cathodic chamber, and the second surface defines an anodic chamber. The cathodic chamber includes an alkali metal halide that forms an ion that is capable of conducting through the separator. The anodic chamber has a volume that is filled with a consumable fluid. The amount of the consumable fluid is greater than 90 percent by volume of the anodic chamber volume. Furthermore, the consumable fluid is reactive with an ionic species of the alkali metal halide. A method of sealing the energy storage device is also provided.