An energy storage device includes a housing having an interior surface defining a volume and a plurality of solid electrolyte elements disposed in the volume. Each solid electrolyte element has a first surface that defines at least a portion of a first, cathodic chamber, and a second surface that defines a second, anodic chamber. A plurality of individual anode chambers are thus provided, a majority of which are in ionic communication with the cathode chamber through a majority of the solid electrolyte elements and which are also provided with a sodium level control mechanism.