NOVELTY - The cell (10) has a negative electrode compartment (15) including a negative electrode (20). The negative electrode is oxidized to release sodium ions during discharge, and reduces the sodium ions to form sodium metal during recharge. A positive electrode compartment (25) includes a current collector (30) placed in liquid positive electrode solution (35) that comprises halogen and halide. The cell performs reactions in the positive electrode compartment. A sodium ion conductive electrolyte membrane (40) separates the negative electrode from the positive electrode solution.    USE - Sodium-halogen secondary cell for a grid-scale electrical energy storage system and an electrical vehicle.    ADVANTAGE - The sodium ion conductive electrolyte membrane selectively transports the sodium ions and prevents the negative electrode and the positive electrode solutions from mixing so as to provide minimal capacity fade and relatively stable shelf life at ambient temperature. The cell allows a pumping mechanism to force fluid through the negative compartment so as to reduce total amount of sodium in the negative electrode compartment at desired time and reduce damage and danger. The cell can reduce overall battery complexity and total cost through elimination of interconnects hardware and charge control circuitry.    DETAILED DESCRIPTION - The cell utilizes a complexing agent i.e. tetramethyl ammonium halide compound.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of a sodium-halogen secondary cell with a pumping mechanism, where the cell causes a positive electrode solution to flow through a positive electrode compartment and causes a negative electrode to flow through a negative electrode compartment of the cell.    Sodium-halogen secondary cell (10)    Negative electrode compartment (15)    Negative electrode (20)    Positive electrode compartment (25)    Current collector (30)    Liquid positive electrode solution (35)    Sodium ion conductive electrolyte membrane (40)