Principle of the NAS Battery

NAS battery consists of sulfur at positive electrode, sodium at negative electrode as active materials, and Beta alumina of sodium ion conductive ceramic which separates both electrodes.
This hermetically sealed battery is operated under the condition that the active materials at both electrodes are liquid and its electrolyte is solid.

If a load is connected to terminals, electric power is discharged through the load. During the discharge, sodium ions converted from sodium in a negative electrode pass through solid electrolyte then reach to sulfur in positive electrode.
The electrons finally flow to outside circuits. The electric power is generated by such current flow.
With the progress of the discharge, sodium polysulfide is formed in positive electrode; on the contrary, sodium in negative electrode will decrease by consumption.
During the charge, the electric power supplied from outside form sodium in negative electrode and sulfur in positive electrode by following the reverse process of the discharge. Because of this, the energy is stored in the battery.

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Typical System