The present invention provides a molten sodium secondary cell. In some cases, the secondary cell includes a sodium metal negative electrode, a positive electrode compartment that includes a positive electrode disposed in a liquid positive electrode solution, and a sodium ion conductive electrolyte membrane that separates the negative electrode from the positive electrode solution. In such cases, the electrolyte membrane can comprise any suitable material, including, without limitation, a NaSICON-type membrane. Furthermore, in such cases, the liquid positive electrode solution can comprise any suitable positive electrode solution, including, but not limited to, an aqueous sodium hydroxide solution. Generally, when the cell functions, the sodium negative electrode is molten and in contact with the electrolyte membrane. Additionally, the cell is functional at an operating temperature between about 100° C. and about 170° C. Indeed, in some instances, the molten sodium secondary cell is functional between about 110° C. and about 130° C.