SODIUM-SULFUR BATTERY

PURPOSE: To minimize direct reaction between sodium and sulfur in the case of damage of a solid electrolyte tube so as to improve its safety. CONSTITUTION: A safe tube 6A which has an exit 6B of negative electrode activated substance in bottom surface, contains sodium 8 as the negative electrode activated substance in its inside, and positions a spherical body 6D surrounded by metal of low melting point or metal alloy of low melting point in star-shaped, pyramid-shaped or radially in the vicinity of the exit 6B of the negative activated substance is inserted into a negative electrode chamber in a solid electrolyte tube 1. Further, textile fabric or non-textile fabric of metal fiber 7 is inserted between outer periphery surface of the safe tube 6A and inner periphery of the solid electrolyte tube 1, and also upper end of this safe tube 6A is connected to a negative electrode terminal 5. Therefore, in the case of damage of the solid electrolyte tube, the exit of negative electrode activated substance can be closed by the spherical body so that direct reaction between sodium and sulfur can be minimized thereby to improve safety of the battery.