The present invention provides a method for providing electrical potential from a solid-state sodium-based secondary cell (or rechargeable battery). A secondary cell is provided that includes a solid sodium metal negative electrode that is disposed in a non-aqueous negative electrolyte solution that includes an ionic liquid. Additionally, the cell comprises a positive electrode that is disposed in a positive electrolyte solution. In order to separate the negative electrode and the negative electrolyte solution from the positive electrolyte solution, the cell includes a sodium ion conductive electrolyte membrane. The cell is maintained and operated at a temperature below the melting point of the negative electrode and is connected to an external circuit.