NOVELTY - A sodium-metal battery (20) consists of sodium-ion ion conductor (1), negative electrode active material (4) comprising metal sodium, disposed on sodium-ion ion conductor, negative electrode (5) disposed such that at least a portion is in contact with negative electrode active material, organic electrolyte (2) stored to be in contact with the negative electrode and one surface of sodium-ion ion conductor, positive electrode (8) disposed on other side of sodium-ion ion conductor, aqueous electrolyte (3) stored to be in contact with positive electrode, and housing (13).    USE - Sodium-metal battery is used for electric vehicles.    ADVANTAGE - The economical sodium-metal battery has excellent energy density per volume.    DETAILED DESCRIPTION - A sodium-metal battery consists of a sodium-ion ion conductor having sodium-ion ion conductivity, a negative electrode active material comprising metal sodium, disposed on one side of the sodium-ion ion conductor, a negative electrode disposed such that at least a portion is in contact with the negative electrode active material, an organic electrolyte stored to be in contact with the negative electrode and one surface of the sodium-ion ion conductor, a positive electrode disposed on the other side of the sodium-ion ion conductor, an aqueous electrolyte stored to be in contact with the positive electrode and the other surface of the sodium-ion ion conductor, and a housing having base resistance for housing the aqueous electrolyte. The negative electrode is capable of conducting electrons generated when sodium metal ionizes. The organic electrolyte comprises fluoroethylene carbonate.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of structure of the sodium-metal battery.    Sodium-ion ion conductor (1)    Organic electrolyte (2)    Water-soluble electrolyte solution (3)    Negative electrode active material (4)    Negative electrode (5)    Housing (7)    Positive electrode (8)    Sodium-metal battery (20)