Rechargeable hybrid sodium metal-sulfur battery

A method of operating a rechargeable galvanic cell, the method comprising:

• providing a rechargeable galvanic cell comprising
• a negative electrode compartment housing a negative electrode active material, wherein
• the negative electrode active material comprises a liquid alkali metal selected from the group consisting of molten sodium and molten sodium alloys, and
• the negative electrode compartment is in passive fluid communication with a first reservoir such that the liquid alkali metal may passively flow between the negative electrode compartment and the first reservoir as the galvanic cell charges or discharges;
• and
• a positive electrode compartment housing a positive electrolyte comprising a mixture of positive electrode active material and a solvent, wherein
• the positive electrode active material comprises Na2Sx depending on the charge state of the galvanic cell, wherein x has a value between 1 and 32,
• the solvent comprises a polar organic solvent, optionally comprising a polar protic organic solvent, that partially or completely dissolves the Na2Sx, and
• the negative electrode compartment and the positive electrode compartment are separated by a sodium ion conductive ceramic membrane;
• maintaining the temperature of the ceramic membrane, the negative electrode active material, and/or the positive electrolyte at a temperature from about 100° C. to about 130° C.;
• and
• charging or discharging the rechargeable galvanic cell while circulating the positive electrolyte from a second external reservoir through the positive electrode compartment and back to the second external reservoir.