Production of sodium metal by dual temperature electrolysis processes

A method comprising:

• introducing an anolyte at a first temperature of 115° C. to about 150° C. into an anolyte compartment of an electrochemical flow cell, wherein
• the anolyte comprises an effective amount of a sulfur-containing sodium salt dissolved in a temperature-sensitive solvent comprising alkyl diol;
• the anolyte compartment comprises an anode, wherein the anode comprises the sulfur-containing sodium salt;
• the electrochemical flow cell further comprises a catholyte compartment and a ceramic sodium ion conductive membrane that separates the anolyte compartment from the catholyte compartment;
• and
• the catholyte compartment comprises a molten sodium cathode;
• causing sodium ions from the sodium salt to pass through the ceramic sodium ion conductive membrane from the anolyte compartment to the catholyte compartment;
• reducing the sodium ions to sodium metal at the molten sodium cathode;
• and
• cooling the anolyte outside the anolyte compartment to a second temperature of 80° C. to less than 115° C., without recovery of sulfur;
• wherein the second temperature causes degradation of the temperature-sensitive, solvent at a rate less than 20% of the rate that occurs at the first temperature.