A galvanic cell is disclosed. Generally, the cell includes an alkali metal anode, which electrochemcially oxidizes to release alkali metal ions, and a cathode, which is configured to be exposed to an electrolyte solution. A water-impermeable, alkali-ion-conductive ceramic membrane separates the anode from the cathode. Moreover, an alkali-ion-permeable anode current collector is placed in electrical communication with the anode. In some cases, to keep the anode in contact with the current collector as the cell functions and as the anode is depleted, the cell includes a biasing member that urges the anode against the current collector. To produce electricity, the galvanic cell is exposed to an aqueous electrolyte solution, such as seawater, brine, saltwater, etc.