SODIUM-SULFUR BATTERY WITH A SUBSTANTIALLY NON-POROUS MEMBRANE AND ENHANCED CATHODE UTILIZATION
A sodium-sulfur battery is disclosed in one embodiment of the invention as including an anode containing sodium and a cathode comprising elemental sulfur. The cathode may include at least one solvent selected to at least partially dissolve the elemental sulfur and Na 2 S x . A substantially non-porous sodium-ion-conductive membrane is provided between the anode and the cathode to keep sulfur or other reactive species from migrating therebetween. In certain embodiments, the sodium-sulfur battery may include a separator between the anode and the non-porous sodium-ion-conductive membrane. This separator may prevent the sodium in the anode from reacting with the non-porous sodium-ion-conductive membrane. In certain embodiments, the separator is a porous separator infiltrated with a sodium-ion-conductive electrolyte.
1 . A sodium-sulfur battery comprising:
an anode containing sodium;
a cathode comprising elemental sulfur;
the cathode further comprising at least one solvent selected to at least partially dissolve the elemental sulfur and Na 2 S x ; and
a substantially non-porous sodium-ion-conductive membrane separating the anode from the cathode,
where the battery is configured to be operated at a temperature of less than about 200° C.
2 . The sodium-sulfur battery of claim 1 , further comprising a separator between the anode and the substantially non-porous sodium-ion-conductive membrane to keep the anode from reacting with the substantially non-porous sodium-ion-conductive membrane.
3 . The sodium-sulfur battery of claim 2 , wherein the separator is a porous separator.
4 . The sodium-sulfur battery of claim 3 , wherein the porous separator is permeated with a sodium-ion-conductive electrolyte.
5 . The sodium-sulfur battery of claim 1 , wherein the substantially non-porous sodium-ion-conductive membrane is a NASICON membrane.
6 . The sodium-sulfur battery of claim 1 , wherein the substantially non-porous sodium-ion-conductive membrane is a NASICON membrane treated with a sealer to fill the pores thereof.
7 . The sodium-sulfur battery of claim 1 , further comprising a porous structural layer attached to at least one side of the substantially non-porous sodium-ion-conductive membrane to provide support thereto.
8 . The sodium-sulfur battery of claim 7 , wherein the porous structural layer is a porous NASICON layer.
9 . The sodium-sulfur battery of claim 1 , wherein the at least one solvent includes an apolar solvent to dissolve the elemental sulfur and a polar solvent to dissolve the Na 2 S x .
10 . The sodium-sulfur battery of claim 1 , wherein the at least one solvent consists of at least one polar solvent to at least partially dissolve the elemental sulfur and the Na 2 S x .
11 . The sodium-sulfur battery of claim 1 , wherein the at least one solvent consists of tetraglyme.
12 . A method of operating a battery comprising:
generating sodium ions at a sodium-containing anode;
transporting the sodium ions through a substantially non-porous sodium-ion-conductive membrane to a cathode; and
reacting the sodium ions with elemental sulfur at the cathode to generate Na 2 S x , wherein the elemental sulfur and Na 2 S x at least partially dissolve in at least one solvent in the cathode.
13 . The method of claim 12 , further comprising separating the sodium-containing anode from the substantially non-porous sodium-ion-conductive membrane to keep the sodium-containing anode from reacting with the substantially non-porous sodium-ion-conductive membrane.
14 . The method of claim 13 , wherein separating comprises placing a porous separator between the sodium-containing anode and the substantially non-porous sodium-ion-conductive membrane
15 . The method of claim 14 , further comprising permeating the porous separator with a sodium-ion-conductive electrolyte.
16 . The method of claim 12 , wherein the substantially non-porous sodium-ion-conductive membrane comprises a NASICON membrane.
17 . The method of claim 16 , further comprising filling the pores of the NASICON membrane with a sealer.
18 . The method of claim 12 , further comprising supporting the substantially non-porous sodium-ion-conductive membrane with a porous structural layer.
19 . The method of claim 18 , wherein the porous structural layer comprises a porous NASICON layer.
20 . The method of claim 12 , wherein the at least one solvent comprises an apolar solvent to dissolve the elemental sulfur and a polar solvent to dissolve the Na 2 S x .
21 . The method of claim 12 , wherein the at least one solvent comprises at least one polar solvent to at least partially dissolve the elemental sulfur and the Na 2 S x .
22 . The method of claim 12 , wherein the at least one solvent comprises tetraglyme.